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Integrated Contaminant Transport and Fate Modeling System

Version 6.3 January 2006

User’s Guide for

Microsoft Windows

Environmental Software Consultants, Inc. P.O. Box 2622 Madison, Wisconsin 53701-2622 Phone: 608 240-9878 Fax: 608 241-3991 www.seview.com

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Copyright 1994 - 2006 Environmental Software Consultants, Inc.

SEVIEW 6.3 User’s Guide

Environmental Software Consultants, Inc. 2

About the Author and Developer Robert Schneiker has been involved the groundwater consulting industry since 1982. His project experience includes vadose zone and groundwater modeling, risk-based evaluations, remedial investigations, geophysical exploration and groundwater resources exploration. He modeled the migration of petroleum compounds in the unsaturated soil zone using SESOIL for the Wisconsin Department of Natural Resources (WDNR). The results were used to establish the minimum baseline compound-specific soil cleanup standards protective of groundwater quality for the WDNR NR 700 Rule Series regulations. He has presented full-day seminars on the development of site-specific cleanup objectives, risk-based evaluations and remediation through natural attenuation. Since 1985 he has also been a computer consultant and software developer. Mr. Schneiker has a Master of Science degree in Geology/Geophysics from the University of Wisconsin-Milwaukee.



Preface I decided to write SEVIEW in 1993, after performing over 700 SESOIL model simulations used by the Wisconsin Department of Natural Resources (WDNR) to establish default soil cleanup objectives. I used the General Science Corporation RISKPRO system to setup and run SESOIL. RISKPRO proved adequate for setting up and running SESOIL (although, I had to keep track of my modeling activities in an external spreadsheet). However, it provided limited capabilities for documenting the model results. In particular, there was no way of knowing what SESOIL had predicted and how the model scenarios related to each other. So, I decided to write a program that extracted the contaminant mass that volatilized to the atmosphere and the concentration leaching to groundwater. Using this program and a spreadsheet, I was finally able to produce graphs and tables that displayed multiple model results.

To evaluate results from numerous model scenarios, the program summarized the results into several database tables. These tables were later converted into a LOTUS spreadsheet format and were used to produce most of the figures in the Groundwater Contamination Susceptibility Evaluation, SESOIL Modeling report (Ladwig and Hensel, 1993). This approach not only simplified modeling, it allowed my portion of the project to be completed substantially under budget.

Since that time, contaminant transport and fate modeling has become increasingly important as regulatory agencies move toward the establishment of site-specific cleanup objectives based upon risks to human health and the environment and remediation through natural attenuation (RNA). The reasons for this shift are varied and include the financial stability of the reimbursement programs, the increasing discouragement for the disposal of contaminated soil in the limited landfill space, the limited effectiveness of current remedial actions, and the realization that soil types and other site-specific conditions may provide for natural protection of human health and the environment.

There have been four previous versions of SEVIEW available for sale (several other versions were only used internally). The first two versions (2.1 and 2.5) only worked with the SESOIL vadose zone model. These versions simplified model setup and provided tools to extract data. Version 2.6 provided a link between the SESOIL vadose zone model and the BIOSCREEN groundwater model. Version 5.0 provided significant enhancements. It now included the AT123D groundwater model, modeling reports, and a simplified model setup. SEVIEW version 5.0 also included both chemical and climatic databases.

SEVIEW 6.3 includes numerous significant improvements. Improvements include the:

• SESOIL Climatic and Profile and Load Reports, • A 6,674 climatic database, • Option to run AT123D independently, • Ability to load AT123D as a mass or concentration, • Simplified model setup, and • Resizable windows.



SEVIEW was designed to provide environmental professionals with the tools used to evaluate environmental risks to groundwater quality. The overall goal of SEVIEW was to simplify transport and fate modeling to the point where any environmental professional could do it, not just the modelers. This was accomplished by simplifying the model setup process and by producing automated reports. Design specifications for SEVIEW were based on requirements identified during the development of the baseline cleanup standards for the WDNR. SEVIEW was also designed to meet the general modeling requirements identified in the Fundamentals of Ground-Water Modeling, (US EPA, 1992), Assessment Framework for Ground-Water Model Applications (US EPA, 1994) and Applied Groundwater Modeling (Anderson and Woessner, 1992). Additional design specifications were based on numerous modeling projects by consultants using SEVIEW.

Everyone who performs SESOIL modeling has benefited from the development of SEVIEW. The SEVIEW mass balance report was used to identify a significant mass balance error in SESOIL.



Acknowledgments Many people helped to make SEVIEW Version 6.3 a reality; SEVIEW and this User’s Guide are dedicated to them. My thanks to Bill Bristol of the Wisconsin State Geological Survey for long discussions regarding program development and to his sister Deb Radder, President of Engineered Plastics Corporation, for providing a work environment where I could refine my programming skills. I wish to thank my cousin Bill Hood who introduced me to numerous programming languages as we traded Commodore 64 programs as though they were baseball cards. Finally, there is Mike Barden of GeoScience Resources, Ltd. in Albuquerque, New Mexico, who provided technical support on many aspects regarding the development of SEVIEW. Beta copies of SEVIEW 6.3 were distributed to several users. Their feedback and patience is appreciated. SEVIEW became a better program because of their input. Several users' who deserve recognition are:

Liliana Cecan ARCADIS Anne Lewis-Russ Earth Tech, Inc. Dennis Smalley Smalley & Associates, Inc.

Marc Bonazountas and Janet Wagner deserve thanks for developing SESOIL. A special thank you to David Hetrick for his continuing efforts to improve SESOIL. Thanks to G. T. Yeh for developing AT123D. Additional thanks to John A. Hoopes, Howard Trussel and everyone at the University of Wisconsin-Madison and the WDNR who helped to improve AT123D. Thanks also to everyone involved in the development of BIOSCREEN. Robert A. Schneiker May 2005



Information within this document is subject to change without notice. Environmental Software Consultants, Incorporated (ESCI) has made every effort to ensure the accuracy of this User’s Guide. However, ESCI makes no warranties with respect to this documentation and disclaims any implied warranties or fitness for a particular purpose. ESCI assumes no responsibility for any errors that may appear in this document. Copyright © 1994 - 2006 Environmental Software Consultants, Incorporated. All rights reserved. No part of this document may be copied, stored in a retrieval system, transmitted or reproduced in any form, without the express written permission of Environmental Software Consultants, Incorporated. Copy Protection The SEVIEW software program, available only from ESCI and is copy protected. The SEVIEW package is protected by the copyright laws that pertain to computer software. It is illegal to make copies of the contents of the disks except for your own backup, without written permission from ESCI. In particular, it is illegal to give or sell a copy of this software to another individual or entity. Trademark Acknowledgments Visual FoxPro, Visual BASIC, Visual C++, Excel, MS-DOS and Windows are registered trademarks of Microsoft Corporation. dBASE is a registered trademark of Borland International, Inc. Document No. ESCI-SV-6.3-2006-a Manufactured in the United States of America



1 ESCI License Agreement This is a legal agreement between you (either an individual or entity), the end user licensee (Licensee) and Environmental Software Consultants Incorporated (ESCI). If you do not agree to the terms of this Agreement promptly return the disks and other items that are part of this product in their original package, to ESCI for a full refund. No part of this program and all accompanying documentation, including the User’s Guide and disks (the software) may be copied or reproduced in any form or by any means without the prior written consent of ESCI, with the exception that the Licensee may copy the software for backup purposes. License Grant. ESCI grants to the Licensee a nonexclusive right to sublicense, to install this copy of the SEVIEW software on a single computer at a time. You may not rent or lease the software, however you may permanently transfer the software, provided you retain no copies and the recipient agrees to the terms of this Agreement. You may not reverse engineer, decompile, or disassemble the software. Further, you may not network the software or otherwise use it on more than one computer or computer terminal at the same time. The software is owned by ESCI and is protected by United States copyright laws and international treaty provisions. Copyright. The software (including any images and text incorporated into the software) is owned by ESCI and is protected by United States copyright laws and international treaty provisions. Therefore, you must treat the software like any other copyrighted material except that you may either (a) make one copy of the software solely for backup or archival purposes, or (b) transfer the software to a single hard disk provided you keep the original solely for backup or archival purposes. You may not copy the printed material accompanying the software, nor print copies of any user documentation provided in electronic form. Limited Warranty. ESCI warrants that the software will perform substantially in accordance with the accompanying material for a period of ninety (90) days from the date of receipt. Any implied warranties on the software are limited to 90 days. Some states/jurisdictions do not allow limitations of an implied warranty, so the above limitations may not apply to you. End User Remedies. ESCI’s entire liability and your exclusive remedy shall be, for any breach of warranty, at ESCI’s option, either (a) return of the price paid or (b) repair or replacement of the software that does not meet ESCI’s Limited Warranty. This Limited Warranty is void if failure of the software has resulted from accident, abuse or misapplication. Any replacement software will be warranted for the remainder of the original warranty period or 30 days, whichever is longer. NO OTHER WARRANTIES. To the maximum extent permitted by applicable law, ESCI disclaims all other warranties, either expressed or implied, including but not limited to implied warranties of merchantability and fitness for a particular purpose, with respect to the software and accompanying written materials. This limited warranty gives you specific legal rights. You may have others that vary from state/jurisdiction to state/jurisdiction. NO LIABILITY FOR CONSEQUENTIAL DAMAGES. To the maximum extent permitted by applicable law, in no event shall ESCI or its suppliers be liable for any damages whatsoever (including, without limitation, damages for loss of business profits, business interruption, loss of business information, or other pecuniary loss) arising out of the use or inability to use this ESCI product, even if ESCI has been advised of the possibility of such damages. Because some states/jurisdictions do not allow the exclusion or limitation of liability for consequential or incidental damages, the above limitations may not apply to you. Term. This license is effective until terminated. You may terminate it at any time by destroying the software. It will also be terminated upon conditions set forth elsewhere in this Agreement or if you fail to comply with any terms or conditions of this Agreement. You agree upon such termination to destroy the software together with all copies, modifications and merged portions in any form. General. This entire Agreement between Licensee and ESCI supersedes any prior agreement whether written or oral relating to the subject matter in this Agreement. In the event of invalidity of provisions, the parties agree that such invalidity shall not affect the validity of the remaining portions of the Agreement. This Agreement will be governed by the laws of the State of Wisconsin. Should you have any questions concerning this Agreement, you may contact ESCI by writing to Environmental Software Consultants, Incorporated, P.O. Box 2622, Madison, Wisconsin 53701-2622.



�Table of Contents

1 ESCI LICENSE AGREEMENT.......................................................................................................................................7

2 GETTING STARTED.......................................................................................................................................................14 2.1 INTRODUCTION ................................................................................................................................14

2.1.1 SEVIEW Models ....................................................................................................................14 2.1.1.1 SESOIL ........................................................................................................................................... 15 2.1.1.2 AT123D .......................................................................................................................................... 15 2.1.1.3 BIOSCREEN................................................................................................................................... 16

2.1.2 SEVIEW Goals.......................................................................................................................17 2.1.2.1 Simplified SEVIEW Installation ..................................................................................................... 17 2.1.2.2 Simplified Activation ...................................................................................................................... 17 2.1.2.3 Scaleable Windows ......................................................................................................................... 17 2.1.2.4 Project Journal................................................................................................................................. 17 2.1.2.5 Model Setup .................................................................................................................................... 17 2.1.2.6 Climatic Database ........................................................................................................................... 18 2.1.2.7 Chemical Database .......................................................................................................................... 18 2.1.2.8 SESOIL Reports.............................................................................................................................. 18 2.1.2.9 SESOIL - AT123D Link ................................................................................................................. 18 2.1.2.10 AT123D Reports ............................................................................................................................. 19 2.1.2.11 BIOSCREEN Link (from SESOIL to BIOSCREEN) ..................................................................... 19 2.1.2.12 Documentation of Modeling Activities ........................................................................................... 19 2.1.2.13 Access to All Input and Output Data............................................................................................... 19 2.1.2.14 Compatibility................................................................................................................................... 19

2.2 HOW TO USE THIS MANUAL ............................................................................................................20 2.3 LEARN BY DOING.............................................................................................................................20 2.4 SEVIEW NAVIGATOR .....................................................................................................................21 3 INSTALLATION................................................................................................................................................................22 3.1 BEFORE YOU INSTALL .....................................................................................................................22 3.2 INSTALLING SEVIEW......................................................................................................................22 3.3 ACTIVATING SEVIEW.....................................................................................................................23

3.3.1 Standard Mode ......................................................................................................................23 3.3.2 Trial Mode .............................................................................................................................23

3.4 INSTALLING BIOSCREEN...............................................................................................................25 4 SEVIEW TUTORIALS.....................................................................................................................................................26 4.1 SESOIL TUTORIALS ........................................................................................................................26

4.1.1 Tutorial One -- Setup and Run SESOIL.................................................................................26 4.1.2 Tutorial Two -- SESOIL Reports ...........................................................................................29

4.2 AT123D TUTORIALS .......................................................................................................................36 4.2.1 Tutorial One -- Get BIOSCREEN Data and Run AT123D ....................................................36 4.2.2 Tutorial Two -- Setup and Run AT123D................................................................................38 4.2.3 Tutorial Three -- Reducing AT123D Data.............................................................................40

4.3 BIOSCREEN TUTORIALS................................................................................................................45 4.3.1 Tutorial One -- Establish Default BIOSCREEN Data ...........................................................45

5 USING SEVIEW.................................................................................................................................................................49 5.1 THE SEVIEW NAVIGATOR ..............................................................................................................49 5.2 USING THE SEVIEW MAIN MENU...................................................................................................49

5.2.1 File Options ...........................................................................................................................50 5.2.1.1 Select Default Directory.................................................................................................................. 50 5.2.1.2 Open a SEVIEW Project ................................................................................................................. 50 5.2.1.3 Import a SEVIEW Version 5.0 Journal ........................................................................................... 51 5.2.1.4 Select New SESOIL Output File..................................................................................................... 51 5.2.1.5 View SESOIL Output File .............................................................................................................. 51



5.2.1.6 Edit A SESOIL or AT123D Input File............................................................................................ 52 5.2.1.7 Copy Input Files to Disk ................................................................................................................. 53 5.2.1.8 List Input Files ................................................................................................................................ 53 5.2.1.9 View Graphs.................................................................................................................................... 53 5.2.1.10 Go To DOS ..................................................................................................................................... 55 5.2.1.11 Close ............................................................................................................................................... 55 5.2.1.12 Save................................................................................................................................................. 55 5.2.1.13 Save As... ........................................................................................................................................ 55 5.2.1.14 Print................................................................................................................................................. 55 5.2.1.15 Printer Setup.................................................................................................................................... 55 5.2.1.16 Exit .................................................................................................................................................. 55

5.2.2 Transfer Data ........................................................................................................................56 5.2.2.1 Select Data To Transfer To A SEVIEW Spreadsheet ..................................................................... 56 5.2.2.2 Transfer SESOIL Data to a SEVIEW Spreadsheet.......................................................................... 57 5.2.2.3 Sum Selected SESOIL Data ............................................................................................................ 57

5.2.3 Spreadsheet............................................................................................................................58 5.2.3.1 Create A New SEVIEW Spreadsheet File....................................................................................... 59 5.2.3.2 Add Columns to SEVIEW Spreadsheet .......................................................................................... 59 5.2.3.3 Select A SEVIEW Spreadsheet File................................................................................................ 59 5.2.3.4 View A SEVIEW Spreadsheet File ................................................................................................. 60 5.2.3.5 Export SEVIEW Spreadsheet File To Disk..................................................................................... 60

5.2.4 SESOIL ..................................................................................................................................62 5.2.4.1 Setup SESOIL & AT123D Runs..................................................................................................... 62 5.2.4.2 Run SESOIL.................................................................................................................................... 63 5.2.4.3 Plot SESOIL Results ....................................................................................................................... 64

5.2.4.3.1 Climatic Report .......................................................................................................................... 65 5.2.4.3.2 Profile and Load Report ............................................................................................................. 65 5.2.4.3.3 Hydrologic Cycle Report ........................................................................................................... 66 5.2.4.3.4 Pollutant Cycle Report ............................................................................................................... 68

5.2.4.4 View Summary of SESOIL Results ................................................................................................ 71 5.2.4.5 Export SESOIL Summary Table ..................................................................................................... 72 5.2.4.6 Export SESOIL & AT123D Journal to Disk ................................................................................... 73

5.2.5 BIOSCREEN..........................................................................................................................75 5.2.5.1 Transfer SESOIL Data .................................................................................................................... 75 5.2.5.2 Establish SESOIL Parameters to Transfer to BIOSCREEN............................................................ 75 5.2.5.3 Get BIOSCREEN Data ................................................................................................................... 76

5.2.6 AT123D..................................................................................................................................77 5.2.6.1 Run AT123D................................................................................................................................... 77 5.2.6.2 Set Default AT123D Values............................................................................................................ 77 5.2.6.3 Plot AT123D Results ...................................................................................................................... 77

5.2.7 MODFLOW ...........................................................................................................................79 5.2.7.1 Set MODFLOW Parameters............................................................................................................ 79

5.2.8 Edit ........................................................................................................................................79 5.2.8.1 Undo................................................................................................................................................ 79 5.2.8.2 Redo ................................................................................................................................................ 79 5.2.8.3 Cut................................................................................................................................................... 80 5.2.8.4 Copy................................................................................................................................................ 80 5.2.8.5 Paste ................................................................................................................................................ 80 5.2.8.6 Select All......................................................................................................................................... 80 5.2.8.7 Go to Line ....................................................................................................................................... 80 5.2.8.8 Find ................................................................................................................................................. 80 5.2.8.9 Find Again....................................................................................................................................... 80

5.2.9 Help .......................................................................................................................................81 5.2.9.1 Contents .......................................................................................................................................... 81 5.2.9.2 Search for Help on........................................................................................................................... 81 5.2.9.3 About SEVIEW............................................................................................................................... 81

6 SESOIL PARAMETER SPECIFICATIONS.............................................................................................................82 6.1 INTRODUCTION ................................................................................................................................82 6.2 THE SEVIEW INPUT SCREEN ..........................................................................................................82

6.2.1 SEVIEW Journal....................................................................................................................82



6.2.2 Input Parameters ...................................................................................................................83 6.3 CLIMATE FILE INPUT PARAMETERS .................................................................................................84 6.4 CHEMICAL FILE INPUT PARAMETERS...............................................................................................89 6.5 SOIL FILE INPUT PARAMETERS ........................................................................................................97 6.6 WASHLOAD FILE INPUT PARAMETERS ...........................................................................................104 6.7 APPLICATION FILE INPUT PARAMETERS.........................................................................................108

6.7.1 Column Parameters .............................................................................................................109 6.7.2 Ratio Parameters.................................................................................................................111 6.7.3 Contaminant Load Parameters............................................................................................114 6.7.4 Sub-Layer Load Parameters................................................................................................118 6.7.5 SUMMERS Model Parameters ............................................................................................119

7 BIOSCREEN PARAMETER SPECIFICATIONS ................................................................................................121 7.1 INTRODUCTION ..............................................................................................................................121 7.2 ESTABLISH SESOIL PARAMETERS TO TRANSFER TO BIOSCREEN ..............................................121

7.2.1 BIOSCREEN Input Parameters ...........................................................................................122 7.2.1.1 Chemical Parameters..................................................................................................................... 122

7.2.1.1.1 SESOIL Chemical Name Description...................................................................................... 122 7.2.1.1.2 SESOIL Organic Carbon Partition Coefficient (Koc) ............................................................... 122 7.2.1.1.3 SESOIL First Order Liquid Phase Decay Coefficient .............................................................. 123

7.2.1.2 Soil Parameters.............................................................................................................................. 123 7.2.1.2.1 SESOIL Uppermost Soil Layer Organic Carbon Content ........................................................ 123 7.2.1.2.2 SESOIL Effective Porosity ...................................................................................................... 123 7.2.1.2.3 SESOIL Soil Bulk Density....................................................................................................... 123 7.2.1.2.4 SESOIL Permeability............................................................................................................... 123

7.2.1.3 Auto Save...................................................................................................................................... 124 7.2.1.3.1 Save BIOSCRN4.XLS Using the SESOIL Output File Name................................................. 124

7.2.2 BIOSCREEN Load Parameters ...........................................................................................124 7.2.2.1 Load Options................................................................................................................................. 124

7.2.2.1.1 Transfer Maximum SESOIL Leachate Concentration ............................................................. 124 7.2.2.1.2 Transfer the Width of SESOIL Column................................................................................... 125

7.2.2.2 Source Half life Options................................................................................................................ 125 7.2.2.2.1 Calibrate BIOSCREEN Source Half life to SESOIL Load ...................................................... 125 7.2.2.2.2 Transfer SESOIL Mass Load to Groundwater ......................................................................... 126 7.2.2.2.3 Establish “Infinite” BIOSCREEN Source Mass ...................................................................... 126 7.2.2.2.4 Do Not Alter the BIOSCREEN Half life Data ......................................................................... 126

7.2.3 Dilution Factor Parameters ................................................................................................126 7.3 GET BIOSCREEN DATA...............................................................................................................129 8 AT123D PARAMETER SPECIFICATIONS...........................................................................................................131 8.1 INTRODUCTION ..............................................................................................................................131 8.2 AT123D AQUIFER PARAMETERS ...................................................................................................131 8.3 AT123D INPUT PARAMETERS........................................................................................................136

8.3.1 AT123D Release Coordinates..............................................................................................137 8.3.2 AT123D Substance Parameters ...........................................................................................140 8.3.3 AT123D Output Parameters ................................................................................................142 8.3.4 AT123D Load Parameters...................................................................................................146

9 MODFLOW PARAMETER SPECIFICATIONS..................................................................................................148 9.1 INTRODUCTION ..............................................................................................................................148 9.2 MODFLOW PARAMETERS............................................................................................................148 10 REVIEWING SESOIL RESULTS ..............................................................................................................................150 10.1 THE SESOIL OUTPUT FILE ............................................................................................................151

10.1.1 SESOIL Heading..................................................................................................................151 10.1.2 SESOIL Input.......................................................................................................................151 10.1.3 SESOIL Output ....................................................................................................................152

10.1.3.1 Hydrologic Cycle .......................................................................................................................... 152



10.1.3.2 Washload Cycle ............................................................................................................................ 153 10.1.3.3 Contaminant Mass Load................................................................................................................ 154 10.1.3.4 Contaminant Mass......................................................................................................................... 155 10.1.3.5 Contaminant Depth ....................................................................................................................... 156

10.1.4 Output of Annual Summary .................................................................................................156 11 DOCUMENTING SESOIL RESULTS......................................................................................................................158 11.1 MASS BALANCE REPORT ...............................................................................................................158 11.2 SESOIL DATA SETS ......................................................................................................................159

11.2.1 SESOIL Hydrologic Cycle Reports......................................................................................159 11.2.1.1 Precipitation .................................................................................................................................. 159 11.2.1.2 SESOIL Water Balance................................................................................................................. 159

11.2.2 Additional SESOIL Results ..................................................................................................160 11.2.2.1 Soil Moisture................................................................................................................................. 160 11.2.2.2 Contaminant Concentrations ......................................................................................................... 161

11.2.3 Contaminant Depth..............................................................................................................162 11.2.4 Summing SESOIL Data........................................................................................................162

12 REVIEWING AT123D RESULTS ..............................................................................................................................163 12.1 THE AT123D OUTPUT FILE ...........................................................................................................163

12.1.1 AT123D Heading.................................................................................................................163 12.1.2 AT123D Input Parameters...................................................................................................163 12.1.3 AT123D Results ...................................................................................................................166

12.1.3.1 Initial Results ................................................................................................................................ 166 12.1.3.1.1 Retardation Factor .............................................................................................................. 166 12.1.3.1.2 Retarded Darcy Velocity .................................................................................................... 166 12.1.3.1.3 Retarded Dispersion Coefficients ....................................................................................... 167

12.1.4 Contaminant Concentration Results ....................................................................................167 13 TROUBLE SHOOTING.................................................................................................................................................169 13.1 SOLUTIONS TO COMMON PROBLEMS .............................................................................................169 14 REFERENCES..................................................................................................................................................................171

A1.0 INTRODUCTION TO SESOIL.....................................................................................................................................174

A2.0 SESOIL MODEL DESCRIPTION...............................................................................................................................176 A2.1 THE SOIL COMPARTMENT................................................................................................................177 A2.2 SESOIL CYCLES .............................................................................................................................178 A2.3 HYDROLOGIC CYCLE .....................................................................................................................179

A2.3.1 Annual Cycle........................................................................................................................181 A2.3.2 Monthly Cycle......................................................................................................................182 A2.3.3 Hydrologic Model Calibration ............................................................................................183 A2.4 Sediment Washload Cycle....................................................................................................184 A2.4.1 Implementation in SESOIL ..................................................................................................185

A2.5 POLLUTANT FATE CYCLE ..............................................................................................................186 A2.5.1 Foundation ..........................................................................................................................186 A2.5.2 The Contaminant Depth Algorithm......................................................................................189 A2.5.3 Volatilization/Diffusion........................................................................................................192 A2.5.4 Sorption Adsorption/Desorption And Cation Exchange......................................................193 A2.5.5 Degradation: Biodegradation And Hydrolysis ....................................................................194 A2.5.6 Metal Complexation ............................................................................................................197 A2.5.7 Contamination In Surface Runoff And Washload................................................................198 A2.5.8 Soil Temperature .................................................................................................................198 A2.5.9 Pollutant Cycle Evaluation..................................................................................................199

A3.0 SESOIL DATA INPUT GUIDE.....................................................................................................................................201



A4.0 SESOIL EXAMPLE INPUT DATA FILES...............................................................................................................212

A5.0 SESOIL SERUN.BAT FILE ...........................................................................................................................................214

A6.0 SESOIL ERROR AND WARNING MESSAGES ...................................................................................................215

A7.0 SESOIL REFERENCES..................................................................................................................................................219

B1.0 INTRODUCTION TO AT123D.....................................................................................................................................225 B1.1 ONE- AND TWO-DIMENSIONAL SCENARIOS ...................................................................................226

B1.1.1 Two-Dimensional Scenarios................................................................................................227 B1.1.2 One-Dimensional Scenarios ................................................................................................227

B2.0 AT123D MODEL DESCRIPTION...............................................................................................................................228 B2.1 ADVECTION - DISPERSION EQUATION ............................................................................................228 B2.2 BOUNDARY CONDITIONS ...............................................................................................................229

B2.2.1 Dirichlet Boundary Conditions............................................................................................229 B2.2.2 Neumann Boundary Conditions...........................................................................................230 B2.2.3 Cauchy Boundary Conditions..............................................................................................231 B2.2.4 Radiation Boundary Conditions ..........................................................................................231

B2.3 INITIAL CONDITIONS ......................................................................................................................232 B3.0 VERIFICATION OF AT123D........................................................................................................................................242 B3.1 SOLUTION FOR AN INSTANTANEOUS POINT SOURCE ......................................................................242 B3.2 SOLUTION FOR AN INSTANTANEOUS SEMI-INFINITE LINE SOURCE ................................................244 B3.3 SOLUTION FOR INSTANTANEOUS LINE SOURCE IN A FINITE WIDTH AQUIFER................................246 B3.4 SOLUTION FOR A CONTINUOUS POINT SOURCE IN A FINITE DEPTH AQUIFER.................................248 B4.0 AT123D DATA INPUT GUIDE.....................................................................................................................................250

B5.0 AT123D EXAMPLE INPUT DATA FILE..................................................................................................................256

B6.0 AT123D EXAMPLE OUTPUT FILE...........................................................................................................................257

B7.0 AT123D REFERENCES..................................................................................................................................................261

C1.0 SEVIEW TEXT EDITOR COMMANDS ..................................................................................................................263

D1.0 SEVIEW TECHNICAL SUPPORT.............................................................................................................................266 D1.1 TECHNICAL SUPPORT .....................................................................................................................266 D1.2 CONTACTING TECHNICAL SUPPORT ...............................................................................................266 E1.0 SEVIEW FEEDBACK FORM.......................................................................................................................................268

INDEX..............................................................................................................................................................................................269

LIST OF TABLES

Table 1 Export SEVIEW Spreadsheet File Formats......................................................... 61 Table 2 Export File Formats ............................................................................................. 72 Table 3 Export File Formats ............................................................................................. 73 Table 4 SESOIL and AT123D Modeling Journal*........................................................... 74 Table 5 Animation Tool Bar Controls .............................................................................. 78



Table 6 Short Wave Albedo Values.................................................................................. 87 Table 7 Typical Soil Bulk Density Values ....................................................................... 98 Table 8 Default Values For Intrinsic Permeability ........................................................... 99 Table 9 Default Values for Soil Pore Disconnectedness Index ...................................... 100 Table 10 Default Values for Effective Porosity.............................................................. 101 Table 11 SESOIL Hydrological Output Parameters....................................................... 153 Table 12 Sediment Washload Output File Parameters ................................................... 154 Table 13 Contaminant Mass (�g) Processes in the Output File...................................... 155 Table 14 Contaminant Concentration in the Output File................................................ 156 Table 15 Monthly Soil Moisture Content ....................................................................... 161 Table 16 SESOIL Cycles ................................................................................................ 178 Table 17 AT123D Run Options...................................................................................... 226 Table 18 AT123D Boundary Conditions........................................................................ 229 Table 19 Analytical Solution for an Instantaneous Point Source ................................... 243 Table 20 Analytical Solution for an Instantaneous Semi-Infinite Line Source .............. 245 Table 21 Analytical Solution for an Instantaneous Line Source in a Finite Width Aquifer..... 247 Table 22 Analytical Solution for a Continuous Point Source......................................... 249



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2.1 Introduction

Welcome to SEVIEW 6.3, a powerful Windows based menu-driven integrated contaminant transport and fate modeling system. SEVIEW simplifies transport and fate modeling by simplifying model setup and by linking the SESOIL vadose zone model to the AT123D and BIOSCREEN groundwater models. Version 6.3 can also read BIOSCREEN data for use in AT123D. SEVIEW is the shell from which you can manage all aspects of SESOIL, AT123D and BIOSCREEN transport and fate modeling. This SEVIEW User’s Guide contains detailed descriptions of all model input parameters as well as background information on the models.

The version of SESOIL included with SEVIEW includes an improved mass balance routine. The SESOIL mass balance error had existed for years prior to its discovery using SEVIEW.

SEVIEW was designed to help you evaluate model results and to document modeling activities. This includes a mass balance report, mass fate plots, water balance data and documentation of modeling activities. SEVIEW provides a link between SESOIL and all major word processing, spreadsheet, graphical presentation and database programs. SEVIEW can also be used to edit, log, setup and run multiple SESOIL and AT123D model scenarios.

SEVIEW allows you to focus on modeling not using the models. SESOIL Reports SEVIEW includes graphical SESOIL mass balance reports and substance fate plots, are unique to the SEVIEW data management package, provide detailed information to evaluate the fate of a contaminant in soil. Advanced QA/QC SEVIEW’s advanced QA/QC protocols minimize modeling errors and increase productivity.

2.1.1 SEVIEW Models

SEVIEW works with three separate transport and fate models (SESOIL, AT123D and BIOSCREEN). SESOIL is an unsaturated (vadose) zone model. AT123D and BIOSCREEN are groundwater models. A brief description of each model is provided below. A detailed description of SESOIL and AT123D are provided in Appendices A and B respectively. A description of the BIOSCREEN model is provided in the BIOSCREEN User’s Guide.



Although modifications have been made to both SESOIL and AT123D over the years version numbers of these models has remained almost unchanged. This has lead to confusion as to which is the latest version of the models. To simplify matters and remove confusion version numbers were modified to match the current version of SEVIEW. Modification included with version 6.0 of the models is outlined below.

2.1.1.1 SESOIL

SESOIL is a one-dimensional vertical transport screening-level model for the unsaturated (vadose) zone. It simulates contaminant transport and fate based on diffusion, adsorption, volatilization, biodegradation, and hydrolysis. SESOIL is an acronym for the Seasonal Soil compartment model. It is designed to simultaneously model contaminant, soil water and sediment transport in the soil. Its ability to simulate seasonal climatic variation is what sets SESOIL apart and makes it one of the best vadose zone models. It was developed for the EPA’s Office of Water and the Office of Toxic Substances in 1981 by Bonazountas and Wagner, at Arthur D. Little, Incorporated. SESOIL is a public domain program and is written in FORTRAN. SESOIL has been updated several times. The version of SESOIL included with SEVIEW includes modifications made in 1997 by M. J. Barden then at the Wisconsin Department of Natural Resources to correct a mass balance error. SESOIL was further modified by R. A. Schneiker to run to 999 years. The SEVIEW version of SESOIL has enhanced to allow for separate loads to each of the up to 40 sub-layers. SESOIL 6.0 also includes a value for the water diffusion coefficient. This parameter is not used by SESOIL and is simply pasted on to AT123D. Although the SESOIL chemical input file format was modified to include the water diffusion coefficient, compatibility with earlier chemical input files was maintained (Section 6.4). Version 6.0 of SESOIL includes a modification to the method of reading model input files. This means that the user no longer needs to make changes to the config.sys and autoexec.bat files for SESOIL to run.

2.1.1.2 AT123D

AT123D is a generalized three-dimensional model groundwater transport and fate model. AT123D is an acronym for Analytical Transient 1-, 2-, and 3-Dimensional Simulation of Waste Transport in the Aquifer System. It was developed by G. T. Yeh in 1981, at Oak Ridge National Laboratory. The AT123D program is written in FORTRAN. Significant modifications were made by John Seymor (1982), Darryl Holman (1984) and Howard Trussell, (1986) of the University of Wisconsin-Madison. AT123D was further modified by Robert A. Schneiker (1997) at Environmental Software Consultants, Inc. Version 6.0 of AT123D can simulate up to 1,000 years of contaminant transport when linked to SESOIL and contains a correction to the steady state algorithm.

The AT123D model was developed to simulate contaminant transport under one-dimensional groundwater flow. Results can be used to estimate how far a contaminant plume will migrate and can be compared to groundwater standards to evaluate risk at specific locations and times.



Transport and fate processes simulated by AT123D include advection, dispersion, sorption and biological decay. Contaminant transport in AT123D can be modeled using one of two methods:

1. Contaminant transport without decay, and

2. Contaminant transport with biodegradation simulated as a first-order decay process. The no biodegradation option is used to evaluate the transport and fate of non-degrading contaminants and to evaluate risk based conservative parameters. When linked to SESOIL the SEVIEW version of AT123D can simulate up to 1,000 years of contaminant transport. Version 6.3 of AT123D can simulate over 10,000 years of contaminant transport and contains a correction to the steady state algorithm.

Performance has been significantly improved over previous version of AT123D. Contaminant load can be entered as a concentration or a mass. In addition it also is the only version that has inputs for the organic carbon adsorption coefficient (koc) and soil organic carbon content.

2.1.1.3 BIOSCREEN

BIOSCREEN is a screening level groundwater transport model that simulates transport and fate of dissolved hydrocarbons. It was developed in 1996 for the Air Force Center for Environmental Excellence (AFCEE) Technology Transfer Division by Groundwater Services, Inc. BIOSCREEN is based on the Domenico analytical contaminant transport model and can simulate transport and fate based on advection, dispersion, adsorption and biological decay. It is written in the Microsoft Excel and Microsoft Visual BASIC languages and requires version 5.0 or higher of EXCEL to run. BIOSCREEN can model contaminant transport using the following three model types:

1. Contaminant transport without decay,

2. Contaminant transport with biodegradation simulated as a first order decay process,

3. Contaminant transport with biodegradation simulated as an instantaneous reaction.

BIOSCREEN capabilities are extremely limited. For instance the contaminant source load is assumed to be constant through time. This can be thought of as a contaminated source area of an infinite length in the x direction. Although conservative it does not depict a typical contaminant release.

BIOSCREEN was developed as a screening level model over ___ years ago designed for performance not accuracy. However, since that time computer performance has advanced several orders of magnitude. For example AT123D scenarios which took hours to run can now be completed in seconds.

No changes were made to the BIOSCREEN program.



2.1.2 SEVIEW Goals

SEVIEW Version 6.3 was designed to meet the following goals:

• Simplify model setup • Expand the chemical database • Use BIOSCREEN data as input to AT123D • Incorporate a SESOIL to MODFLOW/MT3D link • Enhance the link between SESOIL and AT123D • Ability to run SEVIEW in a trial mode • Provide additional reports to document modeling activities • Improve compatibility between various versions of the models • Allow user's to activate select portions of SEVIEW.

2.1.2.1 Simplified SEVIEW Installation

Users no longer have to make changes to the config.sys and autoexec.bat files to run SESOIL and AT123D. SEVIEW 6.0 can now be installed in any directory.

2.1.2.2 Simplified Activation

Activation has been simplified by combining the two methods of activating SEVIEW in to a single window.

2.1.2.3 Scaleable Windows

Input windows and report previews including font sizes are now scaleable. Once set each window will return to the size established by the user. This means that SEVIEW 6.3 can now be easily used on any resolution display monitor.

2.1.2.4 Project Journal

Separate project files can now be created and opened in SEVIEW 6.3. This means the model scenarios for separate projects can now be saved as individual project files.

Existing SEVIEW 5.0 journals can imported in to version 6.3.

2.1.2.5 Model Setup

SEVIEW includes a sophisticated input interface in which all SESOIL and AT123D input parameters are presented in one window. Input parameters are presented in tab-organized input screens which are linked to model input files logged in a project journal. Changes are made by simply entering data on the screen. Any changes are saved by moving to the



next line in the journal or by closing the setup window. This means you do not have to individually open and save each input file. This approach dramatically reduces the time it takes to set up model scenarios. Quality control is also improved as the input parameters can be quickly scanned. Modifications to model setup in version 6.3 include elimination of the execution input file. The length of the SESOIL scenario is now entered in the SEVIEW journal. When opened the project journal now returns to last model scenario displayed. A color coded display indicates which scenarios have been run. The application file has been modified to allow up to 10 years of load in a 2, 3 or 4 layer configuration.

2.1.2.6 Climatic Database

SEVIEW now includes a 6,674 location climatic database. The database contains latitude, longitude, elevation, air temperature, cloud cover, relative humidity, short wave albedo, precipitation, length of precipitation events, number of precipitation events per month and the distribution of precipitation events for locations in the United States, Guam, Puerto Rico, and the Virgin Islands. Filter and search capabilities have been added, allowing users to quickly locate climatic data.

2.1.2.7 Chemical Database

SEVIEW includes a 1,491 record chemical database. The database contains water solubilities, air diffusion coefficients, Henry’s Law constants, organic carbon adsorption coefficients, molecular weights and liquid phase biodegradation rate data. Search capabilities have been added, allowing users to quickly locate chemical data.

2.1.2.8 SESOIL Reports

SEVIEW automatically reduces SESOIL results produced by the pollutant and hydrologic cycle sub-models. SESOIL reports now include:

• Climatic Report • Profile and Load Report • Hydrologic Report • Pollutant Cycle Report

2.1.2.9 SESOIL - AT123D Link

SEVIEW provides a link between the SESOIL and the AT123D groundwater transport and fate model. The link combines user-defined default input parameters with the SESOIL modeling results. The SESOIL - AT123D link now includes the water diffusion coefficient. Linked parameters can also be modified later using the SEVIEW setup screen.



2.1.2.10 AT123D Reports

SEVIEW can animate AT123D results as either an area or centerline plot. Animated results provide a simple means of evaluating the vast amount of data generated. A Point of Compliance report displays contaminant concentrations at specific coordinates is also included. Scaleable previews of these reports were added.

2.1.2.11 BIOSCREEN Link (from SESOIL to BIOSCREEN)

SEVIEW version 6.3 includes a link between SESOIL and the BIOSCREEN groundwater transport and fate model. The link combines user defined parameters with SESOIL results. The link also includes an option to calibrate the BIOSCREEN source half life to the monthly load to groundwater from SESOIL. In SEVIEW 6.3 BIOSCREEN will be automatically installed the first time it is used and Excel is opened by SEVIEW.

SEVIEW works with BIOSCREEN versions 1.3 and 1.4.

2.1.2.12 Documentation of Modeling Activities

SEVIEW simplifies documentation of modeling activities with a journal of model scenarios, an automatic summary table of SESOIL results, and by copying model input data files to a report file and/or diskette. A separate window used to view and export the SESOIL summary data was added. Both the SEVIEW journal and SESOIL summary tables can be converted to numerous spreadsheet and database formats, including the EXCEL and Lotus spreadsheets and most database programs.

2.1.2.13 Access to All Input and Output Data

Like earlier versions SEVIEW 6.3 provides access to all SESOIL and AT123D input and output data. Both the SESOIL and AT123D models produce large amounts of output data. Although the SEVIEW program produces numerous reports, it is impossible to anticipate all potential uses of the model results. SEVIEW provides tools that can be used to extract specific data or to present the data in other ways.

2.1.2.14 Compatibility

Input file compatibility between versions of SESOIL has been improved. Data extracted by SEVIEW can be converted to numerous file formats enabling the user to plot or evaluate the model results using spreadsheet and/or data presentation software. Graphs in SEVIEW are made using Microsoft Graph and are compatible with numerous programs including Microsoft Word and EXCEL.



2.2 How to Use This Manual

This User’s Guide is organized to help you get started and to describe SEVIEW’s operation. Typographical Conventions This document utilizes the following the typographical conventions:

Italic Text Indicates user data to be entered. For example, “Type a:setup and press <ENTER>”.

Bold Text Indicates title, command or emphasized information

<ENTER> Keyboard and/or mouse keys are bracketed within < >.

+ A plus sign indicates that both keys must be pressed simultaneously. For example, <CTRL + W>.

View Graphs Underlined letters indicate keyboard short cut commands, used with the <Alt> key. Example: <Alt + R> followed by a <V> to open a table displaying the graphical results.

2.3 Learn by Doing

The tutorials in Chapter 3 provide an easy way to learn the basic SEVIEW commands. Using example input data you will perform SESOIL, AT123D and BIOSCREEN modeling. You may also want to review the tutorials if you have not used SEVIEW for a while.



2.4 SEVIEW Navigator

The SEVIEW Navigator provides direct access to the basic SEVIEW commands used to setup and run the models. The navigator presents a flow chart that displays the relationship between the models with arrows that show the order in which they occur. The advantage of the Navigator is that it shows more clearly than the standard Windows menus can how the SEVIEW commands are related to the modeling process.

For example, to setup and run SESOIL you could select the SESOIL, Setup SESOIL & AT123D Runs command in the main menu to modify your input data. Then click on the SESOIL, Run SESOIL command to run SESOIL. While this method is perfectly useful and correct, the Navigator takes advantage of the visual aspects of Windows by providing a simpler, more direct method. Using the Navigator you can achieve the same results by clicking on the Setup SESOIL and Run SESOIL command buttons in the flow chart.

Additional information regarding the SEVIEW Navigator is presented in Section 5.1.



��

This section provides important information about SEVIEW and the installation process. This section is also designed to help you configure SESOIL and AT123D. The SEVIEW program consists of a CD that contains SEVIEW, SESOIL, AT123D, BIOSCREEN and backup default input files.

3.1 Before You Install

Before you install SEVIEW, be sure your computer meets the following system requirements.

• Microsoft Windows 95 or higher.

• A Pentium 133, or better computer.

• 16 MB of RAM minimum (32 MB or more recommended).

• 7 MB of free disk space1.

• CD drive.

3.2 Installing SEVIEW

Installing SEVIEW is quick and easy. You will be prompted to insert the installation disks in the order they are numbered. To install SEVIEW follow these steps.

This procedure should take less than ten minutes to complete2.

1. Insert the SEVIEW 6.3 CD into the CD drive.

2. Follow the instructions in the dialog boxes displayed on screen.

You can also download and install SEVIEW from the www.seview.com web page.

1 Note: Although SEVIEW will install with as little as 7MB of free disk space, significantly more

free disk space is required to run both SEVIEW and AT123D. 2 Note: To ensure that your hard drive is functioning properly it is recommended that you execute

the SCANDISK utility prior to the installation of SEVIEW.



3.3 Activating SEVIEW

To activate SEVIEW click on the SEVIEW 6.3 shortcut. The first time you run SEVIEW, the SEVIEW Registration form will be displayed on the screen. You will need to fill out the form and activate SEVIEW before you can use it. SEVIEW can be activated in either the standard or trial modes. These modes are identical except that the trial mode will stop working three days after being activated.

If SEVIEW does not activate, call and we will provide you with an updated Activation Code. Call ESCI between 9:30 AM and 4:30 PM CST at (608) 240-9878 or request an Activation Code via email to [email protected].

3.3.1 Standard Mode

The trial mode also provides full access to the SEVIEW help file and to this SEVIEW 6.3 User's Guide. The help file and User's Guide includes detailed information on model input parameters. In addition the User's Guide includes background information on the SESOIL and AT123D models.

3.3.2 Trial Mode

SEVIEW 6.3 can be run in a trial mode for three days. The trial mode is identical to the full version of SEVIEW except that it will stop working after three days. As with the standard mode the trial mode provides full access to the SEVIEW help file and to this SEVIEW 6.3 User's Guide. The help file and User's Guide includes detailed information on model input parameters. In addition the User's Guide includes background information on the SESOIL and AT123D models.

You can run SEVIEW in the trial mode by registering SEVIEW via the internet. Once registered you will receive an activation code to run SEVIEW in the trial mode.

Although provided for free in the SEVIEW trial mode the SEVIEW User's Guide and the SEVIEW help documentation are copyrighted by ESCI.

SEVIEW is a copyrighted software package. Only one active copy may be installed on one computer.



You can purchase a SEVIEW license by clicking on the "Print Order Form" command.

If the SEVIEW registration screen extends off the bottom of your screen simply resize the screen until it fits.

There are several activation options in SEVIEW 6.3. You can select to purchase just SESOIL, or SESOIL plus the climatic and chemical databases. In addition you can purchase just AT123D, or AT123D plus the chemical database.

As part of the activation process SEVIEW may decode the climatic and chemical databases.



The SEVIEW Navigator will be displayed when you close the activation screen. The Navigator provides direct access to the basic SEVIEW commands used to setup and run the models. It presents a flow chart that displays the relationship between the models with arrows that show the order in which they occur. The advantage of the Navigator is that it clearly shows how the SEVIEW commands are related to the modeling process.

SEVIEW is now installed and ready to run. Although the use of SEVIEW is intuitive, it is recommended that you proceed to the tutorials in Section 4 of the SEVIEW User’s Guide prior to modeling (a copy of the SEVIEW User’s Guide can be found in the C:\SEVIEW63 directory). By working through the tutorials you will become familiar with the basic SEVIEW functions and utilities.

3.4 Installing BIOSCREEN

The first time you click on the Copy Data to BIOSCREEN command you will be prompted to install BIOSCREEN.

If you do not install BIOSCREEN in the default directory (C:\BIOSCRN) you will need to locate the BIOSCRN4.XLS file.



� �� There are a total of five SEVIEW tutorials. They are divided in to the SESOIL, AT123D and BIOSCREEN tutorials.

4.1 SESOIL Tutorials

This section contains two SESOIL tutorials. These tutorials are designed to familiarize you with the basic features of setting up and running SESOIL. The tutorials describe procedures used to modify SESOIL input files, run SESOIL and produce automated reports. Upon completing the tutorials you should be able to use the basic SESOIL commands. However, SEVIEW is a feature-filled program and these tutorials do not describe all of the features.

4.1.1 Tutorial One -- Setup and Run SESOIL

As part of this tutorial you will setup and run SESOIL. The SESOIL model uses a total of six input data files. The input data sets contain information pertaining to the climatic, chemical, soil, surface properties (washload), and soil column (application) parameters for each model scenario. In this tutorial you will modify the initial concentration of the contaminant and run SESOIL. An overview of the steps for editing the input file and running SESOIL from within SEVIEW are outlined below.

1. Initiate SEVIEW

2. Setup SESOIL model scenario

3. Run SESOIL

Step 1 Initiate SEVIEW

Initiate SEVIEW (double click on the SEVIEW icon, or select SEVIEW on the Start menu).

Step 2 Setup SESOIL model Scenario

Click on the Setup SESOIL command in the navigator, or select SESOIL and Setup SESOIL and AT123D Runs from the SEVIEW menu presented across the top of the screen. A window displaying the SEVIEW journal and all logged SESOIL and AT123D input files will be opened.

Click on the Application page tab. Then click on the command to create a new SESOIL application file. Enter MYAPP as the file name. Click yes when asked if you want to log the new application file. You have now created a new SESOIL application file.

The SESOIL application file contains information pertaining to the concentration and distribution of a chemical within the soil column, along with some of the physical characteristics of the soil column.



In this tutorial you will establish a load of 0.5 µg/g (ppm) at a depth of 700 to 730 centimeters. To do this click on the Sub-Layer Load screen tab to display the contaminant load parameters and enter 0.5 for the 700 to 730 cm depth interval. You now need to enter a SESOIL output file name. To enter the file name scroll the SEVIEW journal to the left by clicking on the right arrow below the SEVIEW journal or by dragging the scroll bar to the right. Scroll the journal to the right until the SESOIL Output File field appears. Click on the SESOIL Output File and enter run01 from the keyboard. There is no need to enter the full path or the .OUT extension as SEVIEW will add the full path and extension to the output file if you do not.



You now need to select to run the SESOIL model scenario by scrolling the journal to the right until the Run �� SESOIL check box appears. Click on the Run �� SESOIL check box in the SEVIEW journal to select the scenario to be run. Next enter a description of the SESOIL scenario into the “Description of SESOIL Model Scenario” field of the journal.

Finally close the Setup SESOIL & AT123D Runs window to save your changes and to return to the SEVIEW menu.

Step 3 Run SESOIL

Click on the Run SESOIL command in the navigator, or select SESOIL and Run SESOIL from the menu to run SESOIL. SEVIEW will now run SESOIL for all selected scenarios with a complete set of input and output files. If any input files or the output file are left blank or the Run �� SESOIL check box is not checked, SEVIEW will ignore the scenario and move to the next complete set. You should now see the message “SESOIL BEGINS” followed by hydrologic cycle and other monthly information.

Now proceed to Section 4.1.2 to produce reports for your SESOIL scenario. At this point you have setup and run SESOIL and completed the first SEVIEW tutorial. You can now stop working in the tutorial if you wish, or you can continue and evaluate the SESOIL output file you generated. If you continue you will learn how to create the hydrological and pollutant cycle reports.



4.1.2 Tutorial Two -- SESOIL Reports

This tutorial will demonstrate how to generate reports for a SESOIL scenario. Overviews of the steps for this SEVIEW session are outlined below.

1. Initiate SEVIEW

2. Create a Climatic Report

3. Create a Load Report

4. Create a Hydrologic Cycle Report

5. Create a Pollutant Cycle Report

6. Quit SEVIEW

Step 1 Initiate SEVIEW Initiate SEVIEW (double click on the SEVIEW icon, or select SEVIEW on the

Start menu). Click on the SESOIL Reports command in the navigator, or select SESOIL and Plot SESOIL Results from the menu presented across the top of the screen. All SESOIL scenarios logged in the journal will be displayed.



Step 2 Create a Climatic Report Click on the Preview command to generate a hydrologic cycle report to the

screen. Additional information on the Climatic Report is presented in Sections 10 and 11.



Step 3 Create a Load Report Click on the Preview command to generate a Load Report to the screen. As

the Load Report is being created SEVIEW will display information at the bottom of the screen. The information is used to indicating that the program is actively scanning the SESOIL output file and creating the report. Additional information on the Load Report is presented in Sections 10 and 11.



Step 4 Create a Hydrologic Cycle Report Click on the Preview command to generate a hydrologic cycle report. As the

hydrologic cycle report is being created SEVIEW will display information at the bottom of the screen. The information is used to indicating that the program is actively scanning the SESOIL output file. Additional information on the Hydrologic Cycle Report is presented in Sections 10 and 11.



After previewing the Hydrologic Cycle Report on the screen close the window and return to the SESOIL Reports window.

You can print a copy of the Hydrologic Cycle Report directly from the preview screen or by clicking on Print command. To print multiple Hydrologic Cycle Reports click on the �� Print check box for each scenario then click on the Print Select command.

The Hydrologic Cycle Report now includes soil moisture.

Step 5 Creating a Pollutant Cycle Report Click on the SESOIL Reports command in the navigator, or select SESOIL and Plot SESOIL Results from the menu presented across the top of the screen. All SESOIL scenarios logged in the journal will be displayed. Click on the Preview command to generate a pollutant cycle report to the screen. As the pollutant cycle report is being created SEVIEW will display information at the bottom of the screen. The information is used to indicating that the program is actively scanning the SESOIL output file and creating the pollutant cycle report. SEVIEW first will display SESOIL Output and the number of lines in the SESOIL output file and the current line number. SEVIEW will then display the following description as the pollutant cycle report is created: Summing Data, Transferring Data, Mass Balance, Updating Concentration Plot, Updating Mass Fate Plot, Updating Depth Plot and Updating SESOIL Depth Profile. SEVIEW will then present a screen preview of the Pollutant Cycle Report. Additional information on the Pollutant Cycle Report is presented in Sections 10 and 11.



After previewing the Pollutant Cycle Report close the window and return to the SESOIL Reports window. You can print a copy of the Pollutant Cycle Report directly from the preview screen or by clicking on Print command. To print multiple Pollutant Cycle Reports click on the �� Print check box for each scenario then click on the Print Select command.

Step 4 Exit SEVIEW



To end your SEVIEW session, select the File option on the main menu, then select Exit or simply close the window.

Congratulations, you have completed both SESOIL tutorials and have become familiar with some of the basic features of SEVIEW. If you have not used SEVIEW for a while or have forgotten how to use it, you may want to review these tutorials. The next section provides two tutorials on using AT123D in SEVIEW. Skip to Section 4.2.2 to continue this tutorial.



4.2 AT123D Tutorials

This section contains three AT123D tutorials. It is assumed that you have completed the SESOIL tutorials (Section 4.1). These tutorials are designed to familiarize you with the basic features of setting up and running AT123D in SEVIEW. Upon completing these tutorials you should be able to execute the basic SEVIEW commands necessary to run AT123D and document the results. However, SEVIEW is a feature-filled program and these tutorials do not describe all of the features.

4.2.1 Tutorial One -- Get BIOSCREEN Data and Run AT123D

As part of this tutorial you will convert BIOSCREEN data and run AT123D. An overview of this process is outlined below.

1. Open BIOSCREEN in Excel

2. Get the BIOSCREEN data

3. Enter additional AT123D data

4. Run AT123D

5. View results Step 1 Open the BIOSCREEN Spreadsheet in Excel

Start Excel and open a BIOSCREEN model scenario.

C:\BIOSCRN|BIOSCRN4.XLS is the default file name for the BIOSCREEN model. Step 2 Get the BIOSCREEN data" command

Click the "Get BIOSCREEN Data" command in the navigator.

AT123D needs two additional input parameters. The first is the x-axis distance of

the contaminant release. The second is the water diffusion coefficient of the contaminant. Both parameters are easily established. The x-axis coordinate of the



contaminant release is based on results of the site investigation. Water diffusion values are readily available in the chemical literature and many agencies have compiled a list of values for the most common contaminants. You can find chemical-specific water diffusion values in the SEVIEW chemical database.

The x-axis distance in BIOSCREEN is assumed to be infinite.

The x-axis coordinate of the release distance must be less than zero.

You can enter the chemical name in BIOSCREEN and SEVIEW will locate the water diffusion value for you.

Water diffusion can be estimated based on molecular weight (see Section 6.4). Step 3 Run AT123D

Click "OK" in the "Additional AT123D Data" window to run AT123D.

AT123D can run very quickly and it may be difficult to observe it running. Now proceed to Section 4.2.3 to view animated results and to produce reports for the AT123D scenarios.



4.2.2 Tutorial Two -- Setup and Run AT123D

As part of this tutorial you will modify the depths at which the concentrations will be determined by AT123D. An overview of the steps for editing the input file and running AT123D from within SEVIEW are outlined below.

1. Initiate SEVIEW

2. Modify AT123D depth parameters

3. Run AT123D Step 1 Initiate SEVIEW

Initiate SEVIEW (double click on the SEVIEW icon, or select SEVIEW on the Start menu).

Step 2 Modify AT123D Depth (z-axis) Parameters

Click on the Setup AT123D command in the navigator, or select SESOIL and Setup SESOIL and AT123D Runs from the SEVIEW menu presented across the top of the screen. A window displaying the SEVIEW journal and all SESOIL and AT123D input parameters will be opened. Click on the AT123D tab to display the input parameters for AT123D. Next click on the Output tab to set the coordinates where the concentrations will be determined. Next click on the second of the Z-Axis Distance (meters) fields and enter a value of 5 meters. Then press enter or click on the next field and enter a value of 10 meters. Using the mouse click on the right arrow below the SEVIEW journal or drag the scroll bar to the right until the Run �� AT123D check box appears. Click on the Run �� AT123D check box in the SEVIEW journal to select the scenario to be run. Next enter a description of the AT123D scenario into the Description of AT123D Model Scenario field. Finally close the Setup SESOIL and AT123D Runs window to save your changes and to return to the SEVIEW menu.

If you do not enter a description of SEVIEW will use the first 80 characters of the SESOIL description as the AT123D description.

It is now easy to run AT123D independently form SESOIL.

AT123D input files are created whenever you print or preview a SESOIL pollutant cycle report.

A detailed description of the AT123D input parameters within SEVIEW are presented in Section 8. A complete list of all AT123D parameters including a description is presented in Appendix B.

You can set the default AT123D parameters. See Section 8.



Step 3 Run AT123D

Click on the Run AT123D command in the navigator, or select AT123D and Run AT123D from the menu to run AT123D. SEVIEW will now run each AT123D scenario marked to run. If the input or output file is left blank, SEVIEW will ignore the scenario and move to the next complete set. You should now see a MS-DOS window open and see the message AT123D STARTS followed by the year being simulated.

If the AT123D input file does not exist SEVIEW will ignore the scenario.

AT123D can run very quickly and it may be difficult to observe it running. Now proceed to Section 4.2.3 to view animated results and to produce reports for the AT123D scenarios. You have now setup and run AT123D and completed the first AT123D tutorial. You can now stop working in the tutorial if you wish, or you can continue and evaluate the AT123D output file you generated. If you continue you will learn how to produce plots of the AT123D results in second tutorial below.



4.2.3 Tutorial Three -- Reducing AT123D Data

This tutorial demonstrates how to view the AT123D results and how to produce three different reports for the AT123D results. The first report presents an area concentration plot. The second report produces a center line concentration report. The third report produces a point of compliance plot at specific coordinates (node). The first two reports are animated to display the distribution of contaminants through time. Overviews of the steps for this SEVIEW session are outlined below.

1. Initiate SEVIEW 2. Animate Area report 3. Animate Center Line report 4. Produce a Point of Compliance report 5. Exit SEVIEW

Step 1 Initiate SEVIEW Initiate SEVIEW (double click on the SEVIEW icon, or select SEVIEW on

the Start menu). Step 2 Animate Area Report Click on the AT123D Reports command in the navigator, or select AT123D

Reports in the Navigator or select AT123D and Plot AT123D Results from the SEVIEW menu to open the AT123D Results window. The AT123D Results window will display all SESOIL and AT123D journal records. Each record in the journal includes the AT123D Input File, AT123D Output File and the AT123D Description field.



Click on the desired line in the journal, next click on the Area Report command button to display the animated AT123D results. SEVIEW will display an animated area plot of the AT123D results. A copy of the area plot report is presented below.

The animation speed is controlled by the speed of your computer.

You can resize the report to fit your screen.

A toolbar including VCR type controls will be presented. Once the animation is started it can be stopped by clicking on the Stop Animation command. You can also use the VCR controls to step forward or backwards and to play the animation forwards or backwards. SEVIEW can produce a printed report by clicking on the printer icon . You can close the report window at any time by clicking on the close icon on the toolbar or by closing the window.

The command is used to toggle the graph between the normalized and maximized modes.

If you click on the VCR controls the report preview background color will change. This is done as even on very fast computer the computer may be so busy creating the animation that it may not instantly respond to your click.

Once the animation is started it will continue until the last time step is reached.

You can double click on the graph to open it in Microsoft Graph.



Step 3 Animate Center Line Report

Click on the desired line in the journal, and then click on the Center Line command button field to display the animated AT123D results. The center line plot is similar to the area plot except that the data is limited to Y = 0.00 meters. A copy of the center line plot report is presented below.

As with the area plot, the speed at which the data is presented is controlled by the speed of your computer.

If you click on the VCR controls the report preview background color will change. This is done as even on very fast computer the computer may be so busy creating the animation that it may not instantly respond to your click.

If the model scenario does not include Y = 0.00 meters, SEVIEW will select the Y values closest to zero as the center line plot.

As with the area plot a VCR type control tool bar will presented below the SEVIEW menu and you can print a copy of the report by clicking on the printer icon . You can close the report window at any time by clicking on the close icon or by closing the window.

The command is used toggle the graph between the normalized and maximized modes.

Once the animation is started it will continue until the last time step is reached.

You can double click on the graph to open Microsoft Graph.



Step 4 Produce a Point of Compliance Report Click on the Point of Compliance command button to display the concentration through time report. The Point of Compliance plot looks similar to the center line plot except that the data is limited to a single coordinate point (node). This can thought of as displaying the concentration through time at a well or the property boundary. A copy of the Point of Compliance report is presented below. Use the portion of toolbar to change the x, y and z coordinates for the report. After selecting the coordinate for the plot click on the (graph) icon to update the report. SEVIEW can produce a printed report by clicking on the printer icon . You can exit the report by clicking on the close icon or by closing the window.



You can double click on the graph to open Microsoft Graph.

Step 5 Exit SEVIEW

To end your SEVIEW session, select the File option on the main menu, then select Exit or close the window.

Congratulations, you have completed both AT123D tutorials and have become familiar with the basic features of running and evaluating AT123D using SEVIEW. If you have not used SEVIEW for a while or have forgotten how to use it, you may want to review these tutorials.



4.3 BIOSCREEN Tutorials

This section contains one BIOSCREEN tutorial. It is assumed that you have completed the SESOIL tutorial (Section 4.1). The tutorial is designed to familiarize you with the basic features of setting up and running BIOSCREEN using SEVIEW. The tutorial describes the procedures used to transfer SESOIL data, run BIOSCREEN and to plot the results. However, SEVIEW and BIOSCREEN are feature-filled programs and these tutorials do not describe all of the features. See the BIOSCREEN User’s Guide for additional tutorials.

4.3.1 Tutorial One -- Establish Default BIOSCREEN Data

As part of this tutorial you will calibrate the BIOSCREEN load over time to the load to groundwater from SESOIL and run BIOSCREEN. Overviews of the steps to perform these tasks are outlined below.

1. Initiate SEVIEW

2. Calibrate BIOSCREEN load to SESOIL

3. Initiate BIOSCREEN

4. Create a Pollutant Cycle Report

5. Transfer SESOIL data to BIOSCREEN

6. Run BIOSCREEN

7. View BIOSCREEN results

8. Exit BIOSCREEN

9. Exit SEVIEW Step 1 Initiate SEVIEW Initiate SEVIEW (double click on the SEVIEW icon, or select SEVIEW on

the Start menu). Step 2 Establish default BIOSCREEN data to transfer from SESOIL

Click on the Establish Default BIOSCREEN Data command in the navigator or select BIOSCREEN and Establish SESOIL Parameters to Transfer to BIOSCREEN from the SEVIEW menu. This will open a window of BIOSCREEN options. Click on the Load tab and click on the Calibrate BIOSCREEN Source Half Life to SESOIL Load option button. Then close the window.



Step 3 Create a Pollutant Cycle Report SEVIEW loads the SESOIL parameters to be transferred to BIOSCREEN

whenever you preview or print Pollutant Cycle Report. Click on the Pollutant Cycle Reports command in the navigator, or select Results and Pollutant Cycle Reports from the menu presented across the top of the screen. Click on the Preview command to generate a pollutant cycle report to the screen.



As the pollutant cycle report is being created SEVIEW will display information at the bottom of the screen. The information is used to indicating that the program is actively scanning the SESOIL output file and creating the pollutant cycle report. SEVIEW first will display SESOIL Output and the number of lines in the SESOIL output file and the current line number. SEVIEW will then display the following description as the pollutant cycle report is created: Summing Data, Transferring Data, Mass Balance, Updating Concentration Plot, Updating Mass Fate Plot, Updating Depth Plot and Updating SESOIL Depth Profile. SEVIEW will then present a screen preview of the Pollutant Cycle Report. Close the preview window.

Step 4 Copy Data to BIOSCREEN

Click on the Copy Data to BIOSCREEN command in the navigator, or select BIOSCREEN and Transfer SESOIL Data from the SEVIEW menu to copy the data to BIOSCREEN.

The first time you click the Copy Data to BIOSCREEN command you will be prompted to install BIOSCREEN.

Step 5 Run BIOSCREEN

Switch to the BIOSCREEN spreadsheet window and enter a value of 8 years for the Simulation Time. Next click on the Recalculate This Sheet command. Then click on the RUN ARRAY command to run BIOSCREEN.

Step 6 View BIOSCREEN Results

Click on No Degradation Model command in the upper right to display the results.



You can also click on the 1st Order Decay Model and Instantaneous Reaction Model commands to display the results for those options.

Step 7 Exit BIOSCREEN

Exit the BIOSCREEN program by clicking on the File, Exit commands in the EXCEL menu or close the window.

Step 8 Exit SEVIEW

To end your SEVIEW session, select the File option on the main menu, then select Exit or close the window.

Congratulations, you have completed the BIOSCREEN tutorial and have become familiar with the basic features of transferring SESOIL data to BIOSCREEN. If you have not used SEVIEW for a while or have forgotten how to use it, you may need to review these tutorials. The following sections of this user’s guide present in-depth information about SEVIEW.



� �� When you start the program you will see both the SEVIEW Navigator and the Main Menu. From the Main Menu you can select sub-menus containing SEVIEW commands. Or you can select commands directly from the Navigator. This section presents a sub-menu by sub-menu description of all Main Menu commands and a description of the Navigator commands.

5.1 The SEVIEW Navigator

The SEVIEW Navigator presents a flow chart which displays the basic steps involved in modeling. The flow chart is composed of SEVIEW command buttons. Each command button in the navigator represents a step in the modeling process and the arrows show the order in which they occur. The Navigator provides several advantages, including: • Displays Relationships between the various models and reports. • Organized Commands into three sections corresponding to the SESOIL, AT123D and

BIOSCREEN models.

The Navigator and Main Menu commands are equivalent and you can use either method at any time.

5.2 Using the SEVIEW Main Menu

SEVIEW is menu driven and is easy to use. However, you do need to be familiar with the basic features of Microsoft Windows™. Starting SEVIEW Expand the program group that contains SEVIEW if necessary. Then double click on the SEVIEW icon. When SEVIEW is started the following menu is displayed. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help The File option lets the user select a working directory, access the printer setup and quit SEVIEW. The File menu also provides access to SESOIL output files. Options to sum and transfer select SESOIL data to a spreadsheet are accessed from the Transfer Data sub-menu. Capabilities to create, modify, select and view spreadsheet files are presented in the Spreadsheet sub-menu. The Results option is used to create pollutant and hydrologic cycle reports and to document modeling activities. The SESOIL menu option is used to setup the SESOIL and AT123D models. The BIOSCREEN menu option is used to establish default BIOSCREEN parameters and to transfer SESOIL data to BIOSCREEN. The AT123D menu option is used to establish default AT123D



parameters, run AT123D and to produce animated reports. The MODFLOW menu option is used to set the default MODFLOW parameters. The Edit sub-menu provides access to the basic Windows edit, cut and paste commands. A detailed description of each menu option is presented below.

5.2.1 File Options

The options of the File command are used to select and view SESOIL output files, establish a working directory and to quit SEVIEW. The File option also provides access to the print and printer setup windows. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Select Default Directory Open a SEVIEW Project Import a SEVIEW Version 5.0 Journal Select New SESOIL Output File View SESOIL Output File Edit a SESOIL or AT123D Input File Copy Input Files to Disk List Input Files View Graphs Go To DOS Close Save Save as... Print Printer Setup Exit

5.2.1.1 Select Default Directory

Use the File, Select Default Directory command to select a default working directory. When selected, SEVIEW will open a window displaying directories from which a directory anywhere on your computer system may be selected. If you do not choose a directory (Cancel is selected, the <ESCAPE> key is pressed, or the window is closed) the directory will not be updated and the current directory will be retained.

5.2.1.2 Open a SEVIEW Project

Use the Open a SEVIEW Project command to load and create a SEVIEW Journal for each project. When selected, SEVIEW will ask if you want to save changes to the current project. If you click yes the model scenarios logged in the SEVIEW Journal will be saved.

You can create a new SEVIEW project Journal by saving the current project with a new file name. For instance when SEVIEW prompts "Do you want to save any changes to the current project?", click "Yes". Then enter "My Project" as the project file name. Next click on the Save command to create the new file. Once the file is saved the "Open Project File" window will be displayed. Select the "My Project" file to open the new project.



If you do not choose a project file (Cancel is selected, the <ESCAPE> key is pressed, or the window is closed) the current project journal will be retained.

5.2.1.3 Import a SEVIEW Version 5.0 Journal

The Import a SEVIEW Version 5.0 Journal File command converts a SEVIEW version 5.0 Journal to a version 6.3 Journal. The journal will be appended to the currently opened SEVIEW journal.

5.2.1.4 Select New SESOIL Output File

The Select New SESOIL Output File command should only be used to access SESOIL data not included in the automated results (Section 5.2.4.3).

This command is used to select the SESOIL (.OUT) output file for which a menu of SESOIL data sets will be created and to load BIOSCREEN transfer parameters. Use the mouse or arrow keys to choose the Select New SESOIL Output File option from the menu. A window displaying all SESOIL output files in the current directory will be opened. When a SESOIL file is selected, SEVIEW searches the output file for SESOIL data sets. During search process SEVIEW will display the current line number along with the length of the file at the bottom of the screen.

You may select a SESOIL output file anywhere on your computer system.

Once completed, the menu of SESOIL data sets for the output files is accessed by choosing the Transfer Data option of the main menu then choosing Select Data To Transfer To The Spreadsheet (See Section 5.2.2).

If a SESOIL output file is not selected or entered (Cancel is selected, <ESCAPE> is pressed) the menu of data sets will not be updated. A table of SEVIEW commands used to select a SESOIL output file is presented below:

Once you see the line number display changing, you can stop the import process by pressing the <ESCAPE> key.

The currently selected SESOIL output file will be displayed on the screen below the SEVIEW main menu.

5.2.1.5 View SESOIL Output File

This command is equivalent to clicking on the command button following the SESOIL Output File in the SETUP SESOIL & AT123D Runs window (see Section 5.2.4.1).



This command is used to examine a SESOIL output file. Use the mouse or arrow keys to select the View SESOIL Output File option of the Spreadsheet menu. A window displaying all SESOIL output files in the current working directory will be displayed. When a SESOIL output file is selected SEVIEW will display the file in a read only format. If a SESOIL output file is not selected (Cancel is selected, <ESCAPE> is pressed or the window is closed) no file will be selected and the main menu will be displayed. A table of SEVIEW commands used to select SESOIL output files for viewing is presented below:

A SESOIL output file anywhere on disk can be selected.

All SESOIL output files have an .OUT extension.

Viewing an output file does not update the menu of SESOIL data sets for transfer later.

Although, the SESOIL file cannot be modified, the file may be saved as a new output file. In addition, the output file may be searched using the Edit and Find or <CONTROL + F> and find again <CONTROL + G> commands. Furthermore, selected data may be copied from the output file using the Windows copy commands (Edit and Copy or <CONTROL + C>). Prior to copying, the text must be highlighted using the select <SHIFT> + directional keys or the mouse. The directional keys include the <UP ARROW>, <DOWN ARROW>, <LEFT ARROW> and <RIGHT ARROW> keys along with the <PAGE UP>, <PAGE DOWN>, <HOME> and <END> keys. Once highlighted, the data may be copied using the copy command <CONTROL + C>, <ALT + E, C> or the mouse. A complete list of the SEVIEW editor commands are presented in Appendix C.

The basic features of the SEVIEW edit command are similar to other Windows text editors and word processors, except it is much faster when working with the very large output files created by SESOIL!

While viewing the output file you may alter the font, font size and line spacing using the mouse or the Format menu option. A summary of the text format commands is presented below.

When you are through examining the SESOIL output file close the window by pressing the <ESCAPE>, <CONTROL + W>, <ALT + F, C> keys, or by using the mouse.

5.2.1.6 Edit A SESOIL or AT123D Input File

You will not typically use this command to create and modify SESOIL and AT123D input files. This command should be used with caution as it is very easy to corrupt the SESOIL and AT123D input files.



The Edit a SESOIL or AT123D Input File option is used to open the SEVIEW text editor and to modify or create SESOIL and AT123D input files. The SEVIEW editor creates and works with the standard ASCII file format required by the SESOIL and AT123D programs. A summary of the SEVIEW text editing commands are presented in Appendix C.

The basic features of the SEVIEW edit command are similar to other Windows text editors and word processors, except it is much faster when working with the very large output files created by SESOIL and AT123D!

You can also use the SEVIEW editor to edit any ASCII file on your computer simply by entering the file name including the extension at the prompt.

Copies of the SESOIL input files are presented in Appendix A. Appendices A and B contain a detailed description of the input file formats and what each SESOIL and AT123D input file contains.

5.2.1.7 Copy Input Files to Disk

This command is used to copy the SESOIL and AT123D input files used as part of the modeling activities to a floppy disk. It selectively copies only the input files logged into the SEVIEW journal. This option is used to document modeling activities and to simplify review by regulatory agencies as they can easily verify or perform additional modeling using the input files on the disk.

5.2.1.8 List Input Files

This command lists all SESOIL and AT123D input files logged in the SEVIEW journal to the LISTING.TXT file. If the LISTING.TXT file exists will be overwritten each time you run this command. This option is used to document modeling activities, you should include the LISTING.TXT file as part of your modeling report documentation. The input data can be used by regulatory agencies to review modeling activities even if the disk containing the input files is lost.

5.2.1.9 View Graphs

The View Graphs option is used to display the graphs produced by SEVIEW. This includes the plots of the SESOIL leachate concentration, mass balance, contaminant depth, precipitation and soil water balance data. The plots also include the groundwater area and center line concentrations from AT123D.



If you have Microsoft Graph installed on your computer, you can double click or right click on the graph to start the Microsoft Graph Program which will temporally replace the SEVIEW menu. A new tool bar providing access to the Graph options is presented below the menu. The Microsoft Graph menu consists of the following options.

Edit View Insert Format Tools Data Help

A brief description of the Microsoft Graph capabilities is presented below. You should refer to your Microsoft Word or EXCEL documentation for a detailed description of Microsoft Graph. The Edit command is used to copy graphs and graph data from SEVIEW to you application The View command is used to display the data sheet window and additional Microsoft Graph tool bars. The Graph data sheet works like a spreadsheet program. The Insert command is used to insert or remove graph Titles, Data Labels, Legends, Axis and Grid Lines. The Format option is used to select the chart type. The Tools option is used to set additional data sheet, chart and color preferences. The Data option is used to select how the data sheet values will be displayed. The Help option provides help for Microsoft Graph.

Additional Microsoft Graph options can be activated by double clicking the left mouse key and by clicking the right mouse.



5.2.1.10 Go To DOS

There is no need to quit SEVIEW to access DOS or to run a DOS program. The Go To DOS option provides easy access to DOS without closing SEVIEW. This command is simply a short cut to opening a DOS window. As with any DOS window, type exit and press enter to close it.

This option can also be used to help debug SESOIL scenarios. Unlike the Run SESOIL command, this window will not close once SESOIL has run. This allows you to view any error messages displayed by SESOIL. To run SESOIL at the DOS prompt, open the Setup SESOIL & AT123D Runs window, select which scenarios to run and close the window. Then open or re-select the SEVIEW DOS Run Command window and type “SERUN” at the DOS prompt.

5.2.1.11 Close

The File, Close option is used to close the currently opened file. If the file has been modified you will be prompted if the changes should be saved.

5.2.1.12 Save

The File, Save option is used to save the currently opened file. If the file has been modified the changes will be saved.

5.2.1.13 Save As...

The File, Save As... option is used to save the currently opened file as a new file. If the new file already exists the user will be asked if the file should be overwritten.

5.2.1.14 Print

The File, Print option is used to print a SESOIL or AT123D input file. The Print option can also be used to print a text file or the contents of the clipboard.

5.2.1.15 Printer Setup

The File, Printer Setup option is used to select the default printer and the paper size and orientation. Specific options presented are determined by your printer.

5.2.1.16 Exit

Use the File, Exit menu or close SEVIEW window to quit. This option should only be used when you have completed all of your modeling and SEVIEW data management



tasks. Keep in mind that there is no need to quit SEVIEW to run SESOIL, AT123D and BIOSCREEN or to use any other DOS or Windows programs.

5.2.2 Transfer Data

The Transfer Data command should only be used to access SESOIL data not included in the automated results (Section 5.2.4.3).

The Transfer Data option of the main menu provides access to the menu of SESOIL data sets imported using the Select New SESOIL Output File command (Section 5.2.1.4) or pollutant and hydrologic cycle reports. The menu of SESOIL data sets can be selected and transferred to a SEVIEW spreadsheet or summed to create additional data sets. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Select Data To Transfer To The Spreadsheet Transfer SESOIL Data to the Spreadsheet Sum Selected SESOIL Data

5.2.2.1 Select Data To Transfer To A SEVIEW Spreadsheet

The currently selected SESOIL output file is the last file imported using the File, Select New SESOIL Output File or the Results, Pollutant Cycle Reports or Hydrologic Cycle Reports.

This option provides access to the menu of SESOIL data sets for the currently selected SESOIL output file. The data set menu will only include data for layers or sub-layers that the substance has reached. Options listed in the menu will also be limited to SESOIL processes active in the model scenario. For example, if SESOIL predicts that a chemical will not reach the lower soil zone within ten years and the model scenario was limited to a ten year run, no lower soil zone data sets will be included in the menu. Choose the data sets to be transferred to the SEVIEW spreadsheet by clicking the <LEFT MOUSE> on the left most column of the data set menu or by pressing the <CONTROL + T> keys. The left-most column will change to black indicating your selection. Use the arrow keys or mouse to navigate through the data set menu. Once you have completed selecting data sets, press the <F5> or <CONTROL + W> keys or use the mouse to close the menu.

You can deselect data sets by clicking the <LEFT MOUSE> on the left most column a second time or by pressing the <CONTROL + T> keys again.

The current menu of data sets will remain selected until you use the Transfer SESOIL Data to the SEVIEW Spreadsheet or import a new SESOIL output file.



5.2.2.2 Transfer SESOIL Data to a SEVIEW Spreadsheet

The Transfer SESOIL Data to a SEVIEW Spreadsheet command copies the selected data sets to a SEVIEW spreadsheet and clears the selections.

If there are not enough columns in the SEVIEW spreadsheet the data sets that were not copied will not be deselected. In addition SEVIEW will display a description of each data set as it attempts the transfer. You can add more columns to the SEVIEW spreadsheet using the Add Columns to SEVIEW Spreadsheet command (Section 5.2.3.2)

If the transfer option is selected and no data sets were selected SEVIEW will search the menu then return to the main menu.

5.2.2.3 Sum Selected SESOIL Data

Mass in SESOIL output can be distributed into as many as 524 monthly data sets. Using the Sum command you can combine mass from specific sub-layers or layers. For example, you could sum the mass contained in soil moisture for all layers and sub-layers within the SESOIL output file. Or you could limit the summation to only the mass in soil moisture contained in all sub-layers within a single soil zone. To access the summation utility, select the Transfer Data option on the main menu. Then select Sum Selected SESOIL Data. The menu of SESOIL data sets will be displayed. Up to two separate conditions may be selected to limit the summation process. The summation condition parameters are selected by copying portions of the data set menu to the clipboard using the Windows copy command. For example, to sum the mass contained in soil air in the lower soil zone simply move to any of the “LOWER SOIL ZONE” menu options. Then using the mouse or selection keys to highlight only the “LOWER SOIL ZONE” portion of the data set description.

Only highlight the "LOWER SOIL ZONE" portion text. Do not highlight the entire line.

Copy the selection to the clipboard using the mouse or the Windows copy commands (Edit and Copy or the <CONTROL + C>). Close the window using the <F5>, <CONTROL + W> keys or mouse to save your selection. The SESOIL data set menu window will be displayed again. This time highlight the “IN SOIL AIR” portion of any data set description. Then copy the selection to the clipboard as above. Close the window using the <F5>, <CONTROL + W> or mouse to save the selection. Upon closing the second SESOIL data set menu SEVIEW will sum the mass in soil air for the lower soil zone and create a new data set labeled “LOWER SOIL ZONE IN SOIL AIR”. The new data set will contain the monthly sum of the mass in soil air for all layers and sub-layers.



The Sum command works differently when summing the mass for SESOIL processes that distribute mass within the soil column and those processes that remove mass from the soil column. For SESOIL processes that distribute the mass within the soil column, the Sum command totals the mass in each layer or sub-layer. For SESOIL processes that remove mass from the soil column the Sum command totals the mass in each layer and sub-layer and adds the total mass lost in all previous time steps.

In other words to keep track of the total mass input into the soil column, you need to add up the mass in each sub-layer or layer plus the mass lost via volatilization to the atmosphere and entering groundwater. SEVIEW automatically keeps track of which mass processes lose mass and those that do not. For a complete list of SESOIL mass processes see Section 10.1.3.4.

The Sum command is not sensitive to the selection order if two summation conditions are entered. However, if only one condition is selected it must be entered at the first data set menu. Simply close the second data set menu without selecting a condition to complete the summation process.

Pressing the <ESCAPE> key at either data set menu will cancel the summation process.

The summation command will work with all SESOIL data sets. It is up to the user to determine the applicability of this operation for each data set.

5.2.3 Spreadsheet

This menu option is only used when creating custom plots not contained in any of the SEVIEW reports.

Use the Spreadsheet menu option to create, modify, select, view and save SEVIEW spreadsheets. In addition the SEVIEW spreadsheets may be converted to common spreadsheet formats. SEVIEW supports a wide variety of spreadsheet formats, including LOTUS and Excel. A description of the SEVIEW Spreadsheet options is presented below. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Create A New SEVIEW Spreadsheet File Add Columns to SEVIEW Spreadsheet Select a SEVIEW Spreadsheet File View a SEVIEW Spreadsheet File Export SEVIEW Spreadsheet File To Disk



5.2.3.1 Create A New SEVIEW Spreadsheet File

Use this option to create a SEVIEW spreadsheet file. SEVIEW spreadsheet files are database tables with an “.SSF” file extension. The “.SSF” extension is used to identify the database as a SEVIEW Spreadsheet File. SEVIEW spreadsheet files are created by selecting the Spreadsheet menu option of the main menu, then selecting the Create A New SEVIEW Spreadsheet File option. The program will then prompt for the number of columns to be created in the SEVIEW spreadsheet file. You can enter the number of columns with the keyboard or you can dial the desired number using the mouse or up and down arrow keys.

You can add additional columns later if you run out of room.

Once you have selected the number of columns and press enter, you will be prompted for a file name. You may enter a new file designation or you may select an existing file. If you select an existing file SEVIEW will ask if want to overwrite it.

If you enter a new file name and you do not included the “.SSF” extension SEVIEW will add it for you.

SEVIEW spreadsheet data is stored in a Visual FoxPro™ database table with an “.SSF” extension. These files are directly compatible with many software packages including Microsoft Excel and Microsoft Word. SEVIEW also can convert the “.SSF” files to most common spreadsheet formats for even greater compatibility. See the Export SEVIEW Spreadsheet File To Disk command for additional information concerning file conversion.

5.2.3.2 Add Columns to SEVIEW Spreadsheet

The Add Columns to SEVIEW Spreadsheet option is used to create additional blank columns at the end of the SEVIEW spreadsheet. SEVIEW will prompt you for the total number of columns to be contained in the SEVIEW spreadsheet file. You can enter the number of columns with the keyboard or you can dial the desired number using the mouse or up and down arrow keys. Once you have entered the number of columns, SEVIEW will return to the main menu. If you press the <ESCAPE> key or do not increase the total number of columns no additional columns will be incorporated into the spreadsheet.

5.2.3.3 Select A SEVIEW Spreadsheet File

The Select A SEVIEW Spreadsheet File command is used to select an existing SEVIEW spreadsheet file. As with other file options, SEVIEW spreadsheet files may be saved anywhere on your system. When a new file is selected, SEVIEW displays the file name on the screen beneath the menu of options.



The Select A SEVIEW Spreadsheet File option can be used to selectively place individual SESOIL data sets in an appropriate spreadsheet for later analysis. For example, one spreadsheet file may contain water balance data for several model scenarios, while another may contain only concentration data.

The SEVIEW spreadsheet will remain selected until you select a new one, run the automated reports, or quit SEVIEW.

You can create and use as many separate SEVIEW spreadsheet files as you want to segregate SESOIL data sets (see Section 5.2.3.1).

5.2.3.4 View A SEVIEW Spreadsheet File

The View A SEVIEW Spreadsheet File command is used to examine the contents of the currently selected SEVIEW spreadsheet file. This option is used to view the contents of the SEVIEW spreadsheet in a read-only format; the data can not be modified.

5.2.3.5 Export SEVIEW Spreadsheet File To Disk

The Export SEVIEW Spreadsheet File To Disk command is used to convert a SEVIEW spreadsheet file to a standard spreadsheet or ASCII delimited file. SEVIEW will display a listing of all files for the default export file format. In addition, SEVIEW will display a description of the default file format above the file listings.

File import procedures within most spreadsheet programs are simplified by separating the SESOIL data into two spreadsheet files.

Microsoft Excel® Version 5.0 (and higher) contains an advanced text import utility that correctly converts the ASCII Tab Delimited files (.TXT) created by SEVIEW into a spreadsheet. Within this import utility, numeric data is converted into a numeric format eliminating the need for a second file. To import the ASCII data in Excel select File, Open then select Text Files (*.PRN, *.TXT, *.CSV) as the file type. Now open a .TXT file created using the ASCII Tab Delimited option within SEVIEW. When the Excel Text Import Wizard command window is displayed select Finish to complete the conversion.

SEVIEW spreadsheet files may be converted to any of the following formats.



Table 1 Export SEVIEW Spreadsheet File Formats

File Type Default Extension

Excel Version 5 .XLS LOTUS .WK1 LOTUS .WKS Symphony .WR1 Symphony .WRK ASCII Tab Delimited File (.TXT) ASCII Comma Delimited .PRN FoxPro 2.x .DBF VisiCalc .DIF MultiPlan .MOD

When exported file formats with a default .TXT, .PRN or .DBF extensions are selected, only one output file is created. However, when exporting to a spreadsheet format, SEVIEW creates two output files. Two spreadsheet files are created to make data manipulation within the spreadsheet program easier. The second spreadsheet file is distinguished by an “a” suffix at the end of the file name. The “a” stands for ASCII as this spreadsheet file contains only the text heading description displayed at the top of each column within the “.SSF” file. The other file contains only the numeric data



presented below the heading descriptions. The two files should be combined within your spreadsheet to restore the original SEVIEW spreadsheet.

The File format option produces a tab delimited ASCII file with a .TXT extension. As import capabilities vary significantly between spreadsheet and data presentation software programs, the obvious file type may not be the best choice. For example, if you are using Microsoft EXCEL Version 5.0, the ASCII Tab Delimited file format is best. If you are unsure of the import capabilities of your spreadsheet program select a compatible spreadsheet file format.

5.2.4 SESOIL

The SESOIL command options are used to setup and run SESOIL. In addition, the SEVIEW journal of SESOIL and AT123D scenarios can be exported to document project activities. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Setup SESOIL & AT123D Runs Run SESOIL Plot SESOIL Results View Summary of SESOIL Results Export SESOIL Summary Table Export SESOIL & AT123D Journal

5.2.4.1 Setup SESOIL & AT123D Runs

The Setup SESOIL & AT123D Runs option is used to setup and log SESOIL model scenarios to be run. A table containing all logged SESOIL input and output files will be displayed. Additional input file fields can be viewed by pressing the <TAB> key or using the horizontal scroll bar at the bottom of the Setup SESOIL & AT123D Runs window. Most of the modeling tasks can be performed from within this window. You can even edit or create SESOIL input files or view SESOIL output files without leaving the window. Input files may be directly entered into the journal or may be selected by clicking on the

command button following each input file. When the command button is clicked, a window displaying all SESOIL input files in the current directory is displayed. Keep in mind a SESOIL input file in any directory or on any disk can be selected. To select a SESOIL input file, double click on it, or select OK, or press <ENTER> to place the file into the appropriate input file column.

SEVIEW validates the existence of the file prior to proceeding to the next input field. SEVIEW also validates all input file types. For example a soil input file can not be inserted into the chemical input file column.

If you click on the command button on a previously run scenario SEVIEW will display a message indicating that the input file cannot be modified.



After you have entered each input file into the journal you must enter a SESOIL output file designation from the keyboard to complete the SESOIL setup. When you enter the output file SEVIEW will determine if the output file designation has been previously logged or if the file already exists. If the output file exists or was previously logged SEVIEW will prompt you for a new output file name.

You do not need to enter the full path and .OUT extension; SEVIEW will add the path and .OUT extension for you.

Now enter a description of the model scenario into the Description of SESOIL Model Scenario column of the table. The description should be brief and indicate what is unique about the model scenario.

The description field can be up to 254 characters long.

You may enter and setup as many SESOIL scenarios as you wish into the journal. New model scenarios are added by copying any existing journal record to the bottom of the table by clicking on the command button at the far right end of the journal. This will copy all SESOIL input files designations, except the output file and scenario description.

Once you have added a record you can use the standard Windows copy and paste commands to modify the input files and scenario descriptions.

SEVIEW limits access to previously run scenarios to protect the integrity of the journal. Although you cannot use the command button to alter the contents of completed scenarios. However you may still directly enter a new description. Journal records are deleted by clicking on the small left most column of the journal. When you click on the column the box will turn black, indicating the record has been marked for deletion. The record will be deleted when you close the SEVIEW journal window.

Prior to starting a new project you may want to delete all of the journal records. However, you should first export the journal using the Export SEVIEW Journal to Disk command (Section 5.2.4.6).

Each time you exit the Setup SESOIL & AT123D Runs window SEVIEW writes the SERUN.BAT file. The SERUN.BAT file runs SESOIL. You can run this bat file by clicking on the Run SESOIL command, or by opening a DOS window, then type “SERUN” and press <Enter>. A copy of a SERUN.BAT file is presented in Appendix A.

5.2.4.2 Run SESOIL

The Run SESOIL option is used to execute SESOIL from within SEVIEW. SEVIEW will execute all completely logged SESOIL scenarios entered in the journal that have not previously been run and are marked to run. See Setup SESOIL & AT123D Runs (Section 5.2.4.1) to learn how to setup the SESOIL scenarios.

If no input files have been logged and selected to be run, SEVIEW will indicate that either the input file data sets are incomplete or they have already been executed.

SESOIL may also be executed by selecting the Go To DOS command option in SEVIEW. At the DOS prompt type “SERUN” and press <ENTER> to run SESOIL. Once SESOIL is running you can return to SEVIEW and continue working.



5.2.4.3 Plot SESOIL Results

The Plot SESOIL Results command is used to preview or print reports. With it you can easily review SESOIL input parameters and results. Once the SESOIL Reports window is open you will see the Climate and SESOIL columns of the SEVIEW journal. The first column presents a print check box. SEVIEW will sequentially print reports for any selected scenarios by clicking on the Print Selected command. If you select to print multiple Climatic Reports, SEVIEW will sort the climate input files prior to printing.

When you select to print multiple Climatic Reports SEVIEW will first sort the journal by climate input files. SEVIEW will produce a Climate Report for each unique input file. If the same climate file is selected more than SEVIEW will ignore the others.

SEVIEW will sort the journal by SESOIL output files prior to printing multiple Profile and Load, Hydrologic Cycle and Pollutant Cycle reports.

You can sort the journal by clicking on the SESOIL Climate File or SESOIL Output File header descriptions.

Use the Select All, Select None and Invert Selection to select which scenarios to print. Individual scenarios can also be selected by clicking on the Print check box in the journal.

The brownish orange color indicates if the SESOIL output file exists.

Click on the Cancel Reports command to stop the printing process.



5.2.4.3.1 Climatic Report This report displays the climatic input parameters for SESOIL.

5.2.4.3.2 Profile and Load Report The Profile and Load Report displays combines information from the soil, chemical and application input files. Ratio input parameter contained in the application file are converted to specific values. The plots display the contaminant load in to each of the SESOIL layers.

Up to 10 years of monthly contaminant load can be established in SEVIEW 6.3.



5.2.4.3.3 Hydrologic Cycle Report The hydrologic cycle report includes two plots and a table. The upper plot displays the distribution of monthly precipitation between surface water runoff and net infiltration. The lower plot displays the distribution of net infiltration between evapotranspiration, groundwater recharge, soil moisture retention, and percent soil moisture content. A table presenting the data plotted and annual totals is presented below the plots.



Results presented in the Hydrologic Cycle Report are based on year two of the SESOIL scenario.



5.2.4.3.4 Pollutant Cycle Report The Pollutant Cycle Reports command is used to generate reports that summarize the SESOIL results and create AT123D input files. All you need to do is open the Pollutant Cycle Reports window and select the SESOIL scenarios to be included.

This command is equivalent to clicking on the Pollutant Cycle Reports command in the navigator.

The pollutant cycle report includes a plot of the mass fate, leachate concentration, and depth of migration. The maximum SESOIL leachate concentration and total depth of contaminant migration are also displayed. The report also includes a mass balance summary for the final month of the scenario and lists all SESOIL input and output files (including a description). A discussion of each portion of the pollutant cycle report is presented below. Addition information on the SESOIL output data is presented in Sections 10 and 11.



5.2.4.3.4.1 SESOIL Mass Fate Plot The mass fate plot displays the monthly distribution of the contaminant in the SESOIL soil column through time. This plot should be review along with the mass balance



summary to ensure that the total mass input is accounted for. The total mass should be within 99 percent to 101 percent of the input.

Although the mass balance routine has been improved, the mass balance report may not total 100 percent of the input during the first several years of the model scenario, as SEVIEW does not include the “DIFFUSED UP” portion of the mass in the pollutant cycle report.

The mass fate plot is a simple way to display a large amount of data. For example it is possible for a single 999 year SESOIL output file to contain 6,281,712 individual monthly mass values.

5.2.4.3.4.2 Leachate Concentration A SESOIL leachate concentration plot is displayed below the mass fate plot. The leachate concentration plot displays the monthly concentration of the contaminant leaving the bottom of the soil column. The maximum SESOIL leachate concentration is also presented just below the leachate concentration plot.

SEVIEW determines the SESOIL leachate concentration by dividing the monthly mass entering groundwater by the monthly volume of groundwater recharge.

5.2.4.3.4.3 Mass Balance Report A mass balance report includes all SESOIL processes and displays the mass and percentage of the input in each process for the final time step. The mass balance report includes both the mass and percentage of mass contained or lost within each SESOIL process. The total mass input and output are displayed just below the list of SESOIL processes. A calculated percentage of the mass accounted for and the difference between the total input and total output are also displayed.

5.2.4.3.4.4 Contaminant Depth Results A depth of migration plot is presented in the lower right portion of the report. The contaminant starting and ending depths along with the total depth (depth to the water table) are presented just above the depth migration plot.

5.2.4.3.4.5 Create AT123D Input Files Each time you preview or print a SESOIL pollutant cycle report SEVIEW creates an AT123D input file. The AT123D input file will have the same name as the SESOIL output file, with an “.ATI” extension. ATI is an acronym for AT123D Input file.

SEVIEW creates the AT123D input file by combining the SESOIL results with the default parameters for AT123D.



If the AT123D input file currently exists SEVIEW will overwrite the file each time you run the Pollutant Cycle Report.

You can edit the AT123D input file at any time by selecting the SESOIL and Setup SESOIL and AT123D Runs option.

SEVIEW will also load the BIOSCREEN parameter whenever you print or preview a Pollutant Cycle Report.

5.2.4.4 View Summary of SESOIL Results

Whenever you print or preview a SESOIL pollutant cycle report, SEVIEW adds a record to a summary table. This summary table looks like an Excel spreadsheet. The summary table includes the description of the SESOIL scenario, the SESOIL output file used, the percent of the mass lost or in each of the SESOIL process, the percent of the total mass accounted for in the last month, a contaminant migration rate, a travel time to the water table, the maximum SESOIL leachate concentration, the infiltration rate at the month of the maximum leachate concentration and the year of the maximum concentration. The summary table also includes several SESOIL parameters that are often used to determine dilution in groundwater. These parameters are Koc (or Kd), porosity, and organic carbon content.

If a contaminant did not reach the water table SEVIEW will estimate a travel time to groundwater based on the migration rate.



5.2.4.5 Export SESOIL Summary Table

The SEVIEW summary table of the SESOIL results can be saved in a number of different file formats. Once converted the table it can be used in spreadsheet programs to calculate groundwater dilution or in word processors programs to summarize the modeling results. The summary table can be converted to any of the following file formats presented in below.

Table 2 Export File Formats


Excel Version 5 .XLS LOTUS .WK1 LOTUS .WKS Symphony .WR1 Symphony .WRK ASCII Tab Delimited File (.TXT) ASCII Comma Delimited .PRN FoxPro 2.x .DBF VisiCalc .DIF MultiPlan .MOD

The File format option produces a tab delimited ASCII file with a .TXT extension.



5.2.4.6 Export SESOIL & AT123D Journal to Disk

A journal chronicling modeling activities is created automatically as you log SESOIL runs within SEVIEW. The journal contains all input and output files and includes a description of each scenario. The Export SESOIL & AT123D Journal To Disk command is used to convert the journal into a spreadsheet or database format for use in other programs. Once converted, the journal can be used in spreadsheet programs or word processing to document modeling activities. The journal can be converted to any of the following file formats presented below.

Table 3 Export File Formats


Excel Version 5 .XLS LOTUS .WK1 LOTUS .WKS Symphony .WR1 Symphony .WRK ASCII Tab Delimited .TXT ASCII Comma Delimited .PRN FoxPro 2.x .DBF VisiCalc .DIF MultiPlan .MOD



Caution: When using the Table/DBF format be careful not to overwrite any of the SEVIEW database files in the C:\SEVIEW63 directory.

A copy of the SEVIEW journal printed as a Microsoft Word document is presented below.

Table 4 SESOIL and AT123D Modeling Journal*

Climate Input

Files Chemical Input

Files Soil Input

Files Application Input

Files Execution Input

Files SESOIL Output

Files Simulated Condition

And Modification Of The Model Input

d:\milwclim.clm d:\benzene.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\benz01.out Benzene, Baseline, B-2 d:\milwclim.clm d:\benk31.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\benz02.out Benzene, Koc = 31, B-2 d:\milwclim.clm d:\benk214.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\benz03.out Benzene, Koc = 214, B-2 d:\milwclim.clm d:\benzene.chm d:\clay01.soi d:\b2ap.apl d:\exec100.exc d:\benz04.out Benzene, OC = 0.1%, B-2 d:\milwclim.clm d:\benzene.chm d:\clay1.soi d:\b2ap.apl d:\exec100.exc d:\benz05.out Benzene, OC = 1.0%, B-2 d:\milwclim.clm d:\ethylben.chm d:\clay.soi d:\b10ap.apl d:\exec100.exc d:\ethly06.out Ethylbenzene, Baseline, B-2 d:\milwclim.clm d:\ethylben.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\ethyl01.out Ethylbenzene, Baseline, B-2 d:\milwclim.clm d:\ethyk95.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\ethyl02.out Ethylbenzene, Koc = 95, B-2 d:\milwclim.clm d:\ethyk380.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\ethyl03.out Ethylbenzene, Koc = 380, B-2 d:\milwclim.clm d:\ethylben.chm d:\clay01.soi d:\b2ap.apl d:\exec100.exc d:\ethyl04.out Ethylbenzene, OC = 0.1%, B-2 d:\milwclim.clm d:\124tmb.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\124tmb01.out 1,2,4-Trimethylbenzene, Baseline, B-2 D:\milwclim.clm d:\124tk592.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\124tmb02.out 1,2,4-Trimethylbenzene, Koc = 592, B-2 D:\milwclim.clm d:\124k1837.chm d:\clay.soi d:\b2ap.apl d:\exec100.exc d:\124tmb03.out 1,2,4-Trimethylbenzene, Koc = 1,837, B-2 D:\milwclim.clm d:\124tmb.chm d:\clay01.soi d:\b2ap.apl d:\exec100.exc d:\124tmb04.out 1,2,4-Trimethylbenzene, OC = 0.1%, B-2 D:\milwclim.clm d:\124tmb.chm d:\clay1.soi d:\b2ap.apl d:\exec100.exc d:\124tmb05.out 1,2,4-Trimethylbenzene, OC = 1.0%, B-2

* As the washload option was not used the washload input file information was deleted from this journal.



5.2.5 BIOSCREEN

The BIOSCREEN menu option is used to transfer SESOIL data into the BIOSCREEN groundwater transport and fate model. RNA processes modeled by SESOIL include advection, dispersion, adsorption and biological decay. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Transfer SESOIL Data Establish SESOIL Parameters to Transfer to

BIOSCREEN Get BIOSCREEN Data

5.2.5.1 Transfer SESOIL Data

You need to start Microsoft EXCEL and load the BIOSCRN4.XLS file prior to transferring data to BIOSCREEN.

The BIOSCREEN spreadsheet file is located in the C:\BIOSCRN directory.

BIOSCREEN requires Microsoft EXCEL Version 5.0 or higher to run.

This command is used to transfer select SESOIL information to the BIOSCREEN model. SESOIL parameters that can be transferred include: the maximum predicted groundwater contaminant concentration, width of the soil column (load), organic carbon partition coefficient (Koc), first-order decay coefficient, chemical name description, permeability, fraction organic carbon content, effective porosity, soil bulk density and the total mass of a substance entering groundwater. SEVIEW can also calibrate the BIOSCREEN source load half life to the mass leaching to groundwater from SESOIL.

Prior to transferring SESOIL data to BIOSCREEN you need to load the SESOIL data from an output by previewing or printing a Pollutant Cycle Report see Section 5.2.4.3.4.

No changes have been made to the BIOSCREEN source code. This is accomplished by transferring data to BIOSCREEN as if it were entered on the keyboard.

5.2.5.2 Establish SESOIL Parameters to Transfer to BIOSCREEN

This command is used to establish which SESOIL parameters will be transferred to the BIOSCREEN spreadsheet. Parameters that can be transferred from SESOIL include: the maximum predicted groundwater contaminant concentration, width of the soil column, organic carbon partition coefficient (Koc), first-order decay coefficient, chemical name description, permeability, fraction organic carbon content, effective porosity, soil bulk density and total mass entering groundwater. The user can also select to calibrate the BIOSCREEN source load half life to the mass load to groundwater from SESOIL. See Section 7 for a detailed description of each parameter.



5.2.5.3 Get BIOSCREEN Data

This command is used to read BIOSCREEN data and convert it to an AT123D input file. AT123D needs two additional input parameters. The first is the x-axis distance of the contaminant release. The second is the water diffusion coefficient of the contaminant. Both parameters are easily established. The x-axis coordinate of the contaminant release is based on results of the site investigation. Water diffusion values are readily available in the chemical literature and many agencies have compiled a list of values for the most common contaminants. See Section 7 for a detailed description of each parameter.

The x-axis distance in BIOSCREEN is assumed to be infinite.

The x-axis coordinate of the release distance must be less than zero.




5.2.6 AT123D

AT123D command options are used to run AT123D, establish default parameters and to document the results. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Run AT123D Set Default AT123D Values Plot AT123D Results

5.2.6.1 Run AT123D

The Run AT123D option is used execute AT123D from within SEVIEW. AT123D will execute all completely logged AT123D scenarios marked to run in the SEVIEW journal. See Setup SESOIL & AT123D Runs (Section 5.2.4.1) to learn how to setup the AT123D scenarios.

If no AT123D scenarios were selected to run, SEVIEW will indicate that either there is no input file or they were no scenarios selected to be run.

Unlike SESOIL scenarios AT123D model runs can be performed as many times as you want. Existing output files will be overwritten each time you run AT123D.

5.2.6.2 Set Default AT123D Values

This command is used to establish default AT123D input parameters. These parameters are combined with the SESOIL results to create AT123D input files. The AT123D input files are created whenever you print or preview a SESOIL Hydrologic Report. A description of the parameters is presented in Section 8.

5.2.6.3 Plot AT123D Results

The Plot Results option is to animate and print reports of the AT123D results. To animate the results click on the Plot Results menu option and select the Area or Center Line commands in the SEVIEW journal in the AT123D Results window.

You can resize the AT123D report preview to fit your display.



The tool bar contains VCR type controls to play the animation forwards and backwards and to stop the animation.

Table 5 Animation Tool Bar Controls

Icon Command Results

Play Backwards Plays animation backward.

Move Back

One Time Step Rewinds the animation one time step.

Stop Stops the animated display of the model results.

Move Forward One Time Step

Advances the animation one time step.

Play Forwards Plays the animation forward.

Prior to displaying the animation, SEVIEW scans the entire AT123D output file to determine the maximum groundwater concentration.

Once the animation is started, it will continue until the initial or final time step is reached or until the Stop command is selected.

In addition to the VCR controls the tool bar contains several other icons. The icon is used to switch between the normalized and maximized display options. The tool bar includes a printer Icon ( ) to print the report and a close icon ( ) to close the animation window. The portion of the tool bar is used to select the depth in the z direction. If you select a new depth it will be displayed when SEVIEW moves to the next time step. The animated results contain more than the graphs. Each report presents many of the AT123D input parameters along with some of the initial results. The reports also contain a table of the AT123D results used in the plots. A different toll bar will be displayed for the Point of Compliance Report preview.

The portion of the tool bar is used to select the

x, y and z coordinates for the plot. The icon is used to update the plot using the newly selected data. The printer Icon ( ) is used to print the report and the ( ) icon is used to close the preview window.



5.2.7 MODFLOW

The MODFLOW command option is used to establish the default MODFLOW parameters. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Set MODFLOW Parameters

5.2.7.1 Set MODFLOW Parameters

This command is used to establish default parameters for the MODFLOW link. The link data is created whenever you print or preview a SESOIL Hydrologic Report. A description of the parameters is presented in Section 9.

5.2.8 Edit

The Edit command options are used when editing or searching text files. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Undo Redo Cut Copy Paste Select All Goto Line Find Find Again

5.2.8.1 Undo

Undo reverses the last action performed on any text. If you repeatedly select Undo, your actions will be reversed all the way to the start of the current editing session. The <CONTROL + Z> short cut keys can also be used to execute the Undo command.

5.2.8.2 Redo

Redo restores the action previously reversed with the Undo command. The Redo command is the opposite of the Undo command. The Redo command is used if you change your mind after using the Undo command. If you repeatedly select Redo, your Undo actions will be restored in the order they were undone. The <CONTROL + R> short cut keys can also be used to execute the Redo command.



5.2.8.3 Cut

The Cut command removes selected text and places it in the Windows clipboard. The Cut command is used when you want to move text from one location to a new location. The Paste command is used to insert the text. The <CONTROL + X> short cut keys can be used to execute the Cut command.

5.2.8.4 Copy

The Copy command places a duplicate copy of the selected text into the clipboard. The Copy command is used when you want to move copies of text and place it in a new location. The Paste command is used to insert the text. The <CONTROL + C> short cut keys can also be used to execute the Copy command.

5.2.8.5 Paste

The Paste command inserts a copy of the clipboard into the current file at the cursor location. To copy text to the clipboard, see the Cut and Copy commands above. The <CONTROL + V> short cut keys can also be used to execute the Paste command.

5.2.8.6 Select All

The Select All command highlights all text to be copied, cut or deleted.

The Select All Command can be used to copy the contents of a SESOIL input file to a new file.

5.2.8.7 Go to Line

The Go to Line command moves the cursor to the beginning of the selected line number.

5.2.8.8 Find

The Find command searches for text within the document. The <CONTROL + F> short cut keys can also be used to execute the Find command.

5.2.8.9 Find Again

The Find Again command repeats the last find. The <CONTROL + G> short cut keys can be used to execute the Find Again command.



5.2.9 Help

The Help command options are used when editing or searching text. File Transfer Data Spreadsheet SESOIL BIOSCREEN AT123D MODFLOW Edit Help Contents Search for Help on... About SEVIEW

5.2.9.1 Contents

Click on the Contents command to view the table of contents for Help for SEVIEW.

5.2.9.2 Search for Help on...

Click the Search for Help on... command to search for specific words or phrases, or choose from a list of keywords.

5.2.9.3 About SEVIEW

The About SEVIEW command provides information on the current version of SEVIEW.



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6.1 Introduction

This section provides a detailed description of each SESOIL input parameter. SESOIL input files can be created in any order. In general you will open an existing SESOIL input file, save it as a new file, and edit the new file. SESOIL input files contain data that describe the physical and chemical characteristics of the model scenario. These input parameters can be obtained from laboratory analysis, field investigations, and values cited in reference literature. At a minimum, four input data files are required to run SESOIL. The four data sets are contained in the climate, soil, chemical, and application files. A fifth data set, the washload file, is optional.

6.2 The SEVIEW Input Screen

The SEVIEW Setup SESOIL and AT123D Runs input screen provides easy access to all model input parameters. The input screen is divided into the journal and tab organized input parameters below.

6.2.1 SEVIEW Journal

The upper portion of the input screen displays four lines of the SEVIEW journal in a spreadsheet like format. You can use the scroll bars to display additional records or to display additional input files. This journal contains a log of your modeling activities. The input files logged in the journal are linked to the input parameters displayed below. A small arrow is displayed indicating which line of the journal is currently active. There are several ways of entering SESOIL input files into the journal.

1. Enter the full file name including the path,

2. Enter only the file name if the file is in the default directory,

3. Use the Windows Copy and Paste commands to copy the files, or

4. Click the mouse on the following the input file, and simply double click on the input file.

Use the command in the journal to add a new line to the journal.

Note: SEVIEW does not allow you to add a blank line to the journal. This was done as most modeling involves sensitivity analysis where only one parameter is changed between model scenarios. Using the copy method means you do



not need to reenter those input files that have not changed.

If you need to change all of the input files simply any line and replace all of the files, just like you would do if you had a blank line.

Using the copy approach cuts the time it takes to setup your model runs.

6.2.2 Input Parameters

The lower portion of the input screen contains page tabs that provide access to all of the SESOIL and AT123D input parameters. The values displayed come from the SESOIL and AT123D input files contained in the active line of the journal displayed above. To modify model input data simply enter the new values into the appropriate parameters. SEVIEW will save your changes whenever you move to a new line in the journal or close the Setup SESOIL and AT123D Runs window. New SESOIL input files are created by clicking on the command displayed on each input data set. Then enter a new file name. You will be asked if you want to log the new input file into the journal.

To create a new model scenario follow these steps:

1. Copy any journal scenario by clicking on the command.

2. Create a new input file by saving the current (original) input file with the command.

3. Log the new input file in the journal.

4. Edit the new input file



6.3 Climate File Input Parameters

The SESOIL climate data set contains information describing the specifics of the local climate. This includes: air temperature, cloud cover, relative humidity, short wave albedo, mean evapotranspiration rate, monthly precipitation, mean length of precipitation events, number of precipitation events per month and the distribution of precipitation events throughout the month. Users can custom-fit data for a particular scenario. A detailed description of each input parameter is provided below.

The following parameter descriptions are provided as a guideline for each of the climate parameters used in SESOIL. Additional information on these parameters is provided in Bonazountas and Wagner (1984).



The following descriptions also apply to the climatic database. The climatic database is opened by clicking on the command displayed in the SESOIL climate input screen tab. A copy of the climatic database screen is presented below.

As you can see this window looks very much like the climate input screen. However, the journal has been replaced with the climatic database. Click on the

command to create a new SESOIL climatic input from the database. If you do not want to update the SESOIL climate file simply close the window.

You can use the View and Locate City commands to find locations in the climate database.

To create and log a new climatic input file from the database follow these steps:


2. Click on the command on the climatic page tab to open the climatic database

3. Locate the new climatic data set.

4. Create a new input file by saving the current (original) input file with the command.

5. Log the new input file in the journal.

6. Edit the new input file (if desired).



Parameter Description of the Climatic Data Set

SESOIL Variable

TITLE

Description Description used to identify the climatic data set. Limited to a maximum of 48 characters in length.

Parameter Air Temperature

Units degrees Celsius

SESOIL Variable

TA

Description An array of the monthly mean air temperature for each month of the year (in degrees Celsius). The air temperature is used to determine the monthly evapotranspiration rates and soil temperatures. If the actual monthly evapotranspiration rates are known [i.e. non-zero values entered for evapotranspiration rates (REP)], then air temperature is not used to calculate evapotranspiration. However, air temperature is always used to calculate soil temperature.

Source of Data NOAA

Parameter Cloud Cover

Units fraction

SESOIL Variable NN

Description An array of the monthly mean cloud cover fraction for each month of the year (dimensionless fraction ranging from 0.0 to 1.0) used to calculate evapotranspiration rates. If the monthly evapotranspiration rates are known [i.e. non-zero values entered for evapotranspiration rates (REP)] then the percent cloud cover is not used.

Source of Data NOAA

Parameter Relative Humidity

Units fraction

SESOIL Variable S

Description An array of the monthly mean relative humidity for each month of the year (dimensionless fraction ranging from 0.0 to 1.0) used to calculate evapotranspiration rates. If the monthly evapotranspiration rates are [i.e. non-zero values entered for evapotranspiration rates (REP)], then the percent relative humidity is not used.

Source of Data NOAA



Parameter Short Wave Albedo

Units Fraction

SESOIL Variable A

Description The albedo fraction is the ratio of the reflective short wave energy to the incoming energy. An array of the short wave albedo fraction for each month of the year (dimensionless fraction ranging from 0.0 to 1.0) used determine soil temperature which is used to calculate evapotranspiration rates. If the monthly evapotranspiration rates are known [i.e. non-zero values entered for evapotranspiration rates (REP)], then the short wave albedo fractions not used.

Source of Data Table 6 Short Wave Albedo Values Surface Range Typical

Values

Soil and Bedrock Dark moist soil with high humus content 0.05 - 0.15 0.10 Gray moist soil 0.10 - 0.20 0.15 Dry desert soil 0.20 - 0.35 0.30 Sand, wet 0.20 - 0.30 0.25 Sand, light dry 0.30 - 0.40 0.35 Soil (black, moist) 0.05 - 0.10 - - Soil (black, dry) 0.10 - 0.15 - - Desert 0.25 - 0.40 0.37 Desert, clayey 0.29 - 0.31 - - Granite 0.12 - 0.18 - - Rocks in general 0.12 - 0.15 - - Sand, wet 0.15 - 0.25 - -

Snow Fresh dry snow 0.70 - 0.90 0.80 Old snow 0.60 - 0.75 0.70 Dirty snow 0.40 - 0.75 - - Thawing snow 0.35 - 0.65 0.50

Vegetation Grasses 0.15 - 0.30 0.20 Green grass 0.18 - 0.27 - - Green vegetation (short) 0.10 - 0.20 0.17 Grassland parched 0.16 - 0.30 - - Grassland, dry 0.25 - 0.30 - - Dry vegetation 0.20 - 0.30 0.25 Forests 0.05 - 0.20 - - Coniferous forest 0.10 - 0.15 0.12 Green deciduous forest 0.15 - 0.25 0.17 Yellow deciduous forest (autumn) 0.33 - 0.38 - -

Man Made Surfaces Concrete 0.15 - 0.35 0.20 Asphalt 0.05 - 0.10 0.07



Parameter Evapotranspiration Rate

Units cm/day

SESOIL Variable

REP

Description An array of the monthly mean evapotranspiration rate (cm/day) for each month of the year. If 0.0 is entered, SESOIL will calculate evapotranspiration based on air temperature, percent cloud cover, percent relative humidity, and short wave albedo fraction, soil type and depth to groundwater. If a non-zero positive value is entered for the daily evapotranspiration rate, SESOIL will ignore the values for air temperature, cloud cover, relative humidity, and short wave albedo.

Typical Values Daily evapotranspiration rate is typically set to 0.0. By doing so SESOIL will establish evapotranspiration rates based on climatic data, soil properties and depth to groundwater.

Source of Data Site-specific

Be careful if you enter an evapotranspiration rate as the units are in cm/day not cm/month!

Parameter Precipitation

Units cm/month

SESOIL Variable

MPM

Description An array of the total rain precipitation per month (cm/month).

Source of Data NOAA

Parameter Duration of Individual Storm Events

Units days

SESOIL Variable

MTR

Description An array of the mean duration of individual storm events in days, for each month of the year.

Source of Data NOAA



Parameter Number of Storm Events

Units storm events/month

SESOIL Variable

MN

Description An array of the number of storm events per month for each month of the year.

Source of Data NOAA

Parameter Length of Rainy Season

Units days

SESOIL Variable

MT

Description An array of the length of the rainy season (in days) for each month of the year. For most regions in the United States, this parameter should be set to 30.4 (the default value) for all months, since rain events may occur throughout the entire month.

Source of Data NOAA

SESOIL calculates the amount of precipitation that enters the soil column (infiltration) and the amount in the surface water runoff. Water entering the soil column may either, return to the atmosphere by the process of evapotranspiration, remain in soil moisture and/or percolate through the soil column to enter groundwater as recharge. Climatic parameters are used by SESOIL to simulate these processes. Air temperature, cloud cover, humidity, and albedo, are used to estimate evapotranspiration (REP), if a value for this parameter is not provided. If a value for evapotranspiration rate is provided, the model will use that value and will not compute the estimate.

6.4 Chemical File Input Parameters

The chemical input file contains information describing the chemical and physical properties of the contaminant released or applied to the soil column. This information includes water solubility, air diffusion coefficient, Henry’s Law constant, organic carbon adsorption coefficient, soil partition coefficient, molecular weight, valence of the compound, acid, base and neutral hydrolysis rate constants, liquid and solid phase biodegradation rates, ligand stability constant, moles ligand per mole compound, and the molecular weight of the ligand. A copy of the chemical input screen tab and a description of the input parameters are presented below.



The following parameter descriptions are provided as a guideline for each of the chemical parameters used in SESOIL. Additional information regarding these parameters is provided in Bonazountas and Wagner (1984).

The following descriptions also apply to the chemical database. The chemical database is opened by clicking on the command displayed in the SESOIL chemical input screen tab. A copy of the chemical database screen is presented below.



As you can see this window looks very much like the input screen. However the journal has been replace with the chemical database. To copy the data to the SESOIL chemical input file move to the desired chemical and click on the

command and close the database window. If you do not want to update the SESOIL chemical file simply close the window.

As with the SEVIEW journal new records are added by copying existing ones and editing them.

Parameter Description of the Chemical Data Set / Chemical Name

SESOIL Variable TITLE

Description Description used to identify the chemical data set. Limited to a maximum of 48 characters in length.

Parameter Water Solubility

Units (mg/L)

SESOIL Variable SL

Description The solubility of the compound in water at 25° C.

Source of Data Chemical reference literature.

SESOIL requires a water solubility value for the chemical. If the water solubility is unknown and migration to groundwater is the concern, then an estimate that is somewhat high should be used. This will ensure that the estimates of chemical of chemical leaching are conservative.



Parameter Air Diffusion Coefficient

Units cm2/sec

SESOIL Variable DA

Description The diffusion coefficient in air, used by SESOIL to calculate volatilization.

Source of Data Chemical reference literature, or air diffusion coefficient can be estimated using the following relationship:

DA DAMWTMWT

= ''

where:

Parameter Description

DA Air diffusion coefficient of the current compound,

DA' A diffusion coefficient for a reference compound,

MWT' Molecular weight of the reference compound, and

MWT Molecular weight of the current compound.

The diffusion coefficient (0.083 cm2/sec) and molecular weight (131.5 g/mole) for trichloroethylene can be used as the reference compound.

Parameter Henry’s Law Constant

Units M3-atm/mol

SESOIL Variable

H

Description Dimensional form of Henry's Law constant (m3-atm/mole), used in Equations (A7), (A11), and (A13) in Appendix A.


Parameter Organic Carbon Adsorption Coefficient, Koc

Units (µg/g)/( µg/ml)

SESOIL Variable

KOC

Description The adsorption coefficient of the compound on organic carbon. If the adsorption coefficient on the soil Kd, is used, a zero should be entered for organic carbon adsorption coefficient, as it will not be used.




Values entered for Koc, soil partition coefficient (K), liquid phase biodegradation rate, and solid phase biodegradation rate are for the uppermost soil layer and are used as a reference point for the other layers. The layer-specific ratios can be specified in the application file (see Section 6.7).

Parameter Distribution Coefficient, Kd


SESOIL Variable

K

Description The distribution coefficient of the compound on soil. If a non-zero value is entered for the soil partition coefficient (Kd), SESOIL will use this value as the adsorption coefficient. If a zero is entered for the distribution coefficient, SESOIL will calculate Kd by multiplying the organic carbon adsorption coefficient (Koc) times the soil organic carbon content, (OC in the soil input file) see Appendix A, Section A2.5.4.


Adsorption in SESOIL can be represented either by the overall distribution coefficient (K), which is often labeled Kd in the literature, or by the organic carbon:water partitioning coefficient, Koc. If a value for the overall distribution coefficient is unknown, this parameter should be entered as zero. In this case, SESOIL uses the product of Koc and the organic carbon fraction to produce an estimated value for the distribution coefficient (K). If the user enters a measured value for the distribution coefficient, SESOIL will not perform the estimation.

Values entered for distribution coefficient (K) and organic carbon adsorption coefficient (KOC) apply to the uppermost soil layer; layer-specific ratios are entered in the application file.

Parameter Molecular Weight

Units g/mol

SESOIL Variable

MWT

Description The molecular weight of the compound.


Molecular weight is only used if the complexation or cation exchange algorithms are utilized.



Parameter Valence of the Compound

Units g/mol

SESOIL Variable

VAL

Description The valence of the compound used to calculate cation exchange with soil. A positive integer number should be entered without a sign.


VAL is used only if the cation exchange algorithm is used.

Parameter Neutral Hydrolysis Rate Constant

Units L/mol/day

SESOIL Variable

KNH

Description The neutral hydrolysis rate constant (L/mol/day).


Parameter Base Hydrolysis Rate Constant

Units L/mol/day

SESOIL Variable

KBH

Description The base hydrolysis rate constant (L/mol/day).


Parameter Acid Hydrolysis Rate Constant

Units l/mol/day

SESOIL Variable

KAH

Description The acid hydrolysis rate constant (L/mol/day).




Parameter Liquid Phase Biodegradation Rate

Units l/day

SESOIL Variable

KDEL

Description The biodegradation rate of the compound in the liquid phase.


Parameter Solid Phase Biodegradation Rate

Units l/day

SESOIL Variable

KDES

Description The biodegradation rate of the compound in the solid phase.


Parameter Ligand Stability (Dissociation) Constant

Units Dimensionless

SESOIL Variable

SK

Description The stability (dissociation) constant of the compound/ligand complex. A zero should be entered if a ligand compound is not used.


Parameter Moles Ligand per Mole Compound

Units Dimensionless

SESOIL Variable

B

Description The number of moles of ligand per mole of compound complexed. A zero should be entered if a ligand compound is not used.




Parameter Water Diffusion Coefficient

Units cm2/sec

SESOIL Variable

DW

Description Water diffusion coefficient.

Source of Data Chemical-specific.

SEVIEW Link The water diffusion coefficient is not used by SESOIL, however it is passed to AT123D.

The water diffusion coefficient was added to the SESOIL version 6.0 chemical input file. This updated chemical file is compatible (both forward and backward) with SESOIL versions 2.1 and 3.0. Remember, if you use an older version of the chemical file SESOIL 6.0 cannot transfer a water diffusion value to AT123D. Versions 2.1 and 3.0 of SESOIL simply ignore the water diffusion value.

Parameter Molecular Weight of Ligand

Units g/mol

SESOIL Variable

MWTLIG

Description The molecular weight of the ligand (g/mole). A zero should be entered if a ligand compound is not used.


Additional processes for handling the binding of a contaminant to soil constituents are included in the cation exchange and complexation options. The molecular weight and valence of the contaminant are used in the cation exchange calculations. Complexation estimation requires the contaminant's molecular weight, the molecular weight of the ligand participating in the complex, the moles of ligand per mole of contaminant in the complex, and the stability constant of the contaminant/ligand complex.

Cation exchange and complexation are primarily used for metals. Values for these parameters can be set to zero for most other applications.



6.5 Soil File Input Parameters

The soil input file specifies information describing the soil properties for a SESOIL column. This information includes: soil bulk density, intrinsic permeability, soil disconnectedness index, effective porosity, organic carbon content, cation exchange capacity and Freundlich exponent. Vertical variation of soil properties for non-uniform soils consisting of 2, 3, or 4 layers is specified in the application file (Section 6.7.2). Variation within the soil column is based on information supplied in the soil file and applied to the uppermost soil layer. A copy of the soil input screen tab and a description of the input parameters are presented below.

The following parameter descriptions are provided as a guideline for each of the soil parameters used in SESOIL. Additional information regarding these parameters is provided in Bonazountas and Wagner (1984).

To create and log a new soil input file follow these steps:


2. Create a new soil input file by saving the current (original) input file with the command.

3. Log the new soil input file in the journal.

4. Edit the new soil input file.



Parameter Description of Soil Data Set

SESOIL Variable

TITLE

Description Description used to identify the soil data set. Limited to a maximum of 48 characters in length.

Parameter Bulk Density

Units g/cm3

SESOIL Variable

RS

Description The average dry soil bulk density (g/cm3) for the entire soil profile.

Table 7 Typical Soil Bulk Density Values

Soil Type Estimated Bulk Density

(g/cm3)

Sand Silt Clay

1.18 - 1.58 1.29 - 1.80 1.40 - 2.20

Source of Data Geotechnical laboratory analysis or estimated based on soil type.



Parameter Intrinsic Permeability

Units cm2

SESOIL Variable

K1

Description The average soil intrinsic permeability (cm2) for the entire soil profile. If K1 is zero, then the layer-specific intrinsic permeabilities (K11, K12, K13 and K14) specified in the application data file are used instead.

Source of Data Field measurements (slug test, pump tests), geotechnical analysis or estimated based on soil type.

Table 8 Default Values For Intrinsic Permeability

(Bonazountas and Wagner, 1984) USDA Textural Soil

Class Permeability

(cm2)

Clay (very fine) 7.5 X 10-11 Clay (medium fine) 2.5 X 10-10 Clay (fine) 6.0 X 10-10 Silty clay 5.0 X 10-11 Silty clay loam 8.5 X 10-11 Clay loam 6.5 X 10-10 Loam 8.0 X 10-10 Silt loam 3.5 X 10-10 Silt 5.0 X 10-11 Sandy clay 1.5 X 10-9 Sandy clay loam 2.5 X 10-9 Sandy loam 2.0 X 10-9 Loamy sand 5.0 X 10-8 Sand 1.0 X 10-8

Caution! The default values for intrinsic permeability may not be appropriate for a given soil or site and should be used with care.

SESOIL requires permeability in units of intrinsic permeability in cm2. Intrinsic permeability can be estimated by multiplying hydraulic conductivity in units of cm/sec by 1.0 X 10-5 cm sec.

The soil intrinsic permeability (K1) represents the average value for the entire soil column. Intrinsic permeability (K1) should be set to zero in the soil input file, if separate values are entered in the application file, See Section 6.7.2.

Intrinsic permeability, soil disconnectedness index, and effective porosity have been found to be sensitive parameters in SESOIL. It is recommended these values be varied to calibrate results to field data at your site (see Appendix A Section A2.3.3).



Parameter Soil Pore Disconnectedness Index

Units Dimensionless

SESOIL Variable

C

Description The soil pore disconnectedness index for the entire soil profile. Values typically range from 3.7 for sand to 12.0 for fine clay. It relates the soil permeability to the soil moisture content (see Appendix A Section A2.3.3).

Source of Data Typically estimated based on soil type.

Table 9 Default Values for Soil Pore Disconnectedness Index

(Bonazountas and Wagner, 1984) USDA Textural Soil

Class Soil Pore

Disconnectedness Index

Clay (very fine) 12.0 Clay (medium fine) 12.0 Clay (fine) 12.0 Silty clay 12.0 Silty clay loam 10.0 Clay loam 7.5 Loam 6.5 Silt loam 5.5 Silt 12.0 Sandy clay 6.0 Sandy clay loam 4.0 Sandy loam 4.0 Loamy sand 3.9 Sand 3.7

You should not enter value of less than 3.5 for the soil disconnectedness index.



Parameter Effective Porosity

Units Fraction

SESOIL Variable

N

Description The effective porosity for the entire soil profile (unitless). Effective porosity is defined by Eagleson (1978) as;

N = (1 - sr) nt where:


nt Total porosity (volume of voids / total volume)

sr The residual medium saturation (volume of water unmoved by natural forces / volume of voids)

N Effective porosity

Effective porosity should generally have a value that is close to the total porosity, and typically ranges from 0.2 to 0.4.


Table 10 Default Values for Effective Porosity

(Bonazountas and Wagner, 1984) USDA Textural Soil Class Effective Porosity Clay (very fine) 0.20 Clay (medium fine) 0.20 Clay (fine) 0.22 Silty clay 0.25 Silty clay loam 0.27 Clay loam 0.30 Loam 0.30 Silt loam 0.35 Silt 0.27 Sandy clay 0.24 Sandy clay loam 0.26 Sandy loam 0.25 Loamy sand 0.28 Sand 0.30

Although the default values for effective porosity for low permeability soils presented above seem high, Bonazountas and Wagner (1984) found these values to be appropriate for use in the SESOIL model. However, the values for effective porosity should be used with care.



Parameter Organic Carbon Content

Units Percent

SESOIL Variable

OC

Description The organic carbon content of the uppermost soil layer. The relative values of organic carbon content for the lower layers are specified in the application data file.

Source of Data Geotechnical laboratory analysis.

Parameter Cation Exchange Capacity

Units MEq/100 grams dry soil

SESOIL Variable

CEC

Description The cation exchange capacity of the uppermost soil layer. The relative values of the cation exchange capacity for the lower layers are specified in the application data file.


Unless the user has accounted for the combined effects of cation exchange and sorption, these processes should not be used at the same time.

Parameter Freundlich Exponent

Units Dimensionless

SESOIL Variable

FRN

Description The Freundlich Equation Exponent is used to establish the chemical sorption for the top soil layer (see Appendix A, Equation A8). The relative values of Freundlich Equation Exponent for the lower layers are specified in the application data file.

Source of Data Values of Freundlich Equation Exponent typically range from 0.9 to 1.4. If the value is not known, the default value of 1.0 is recommended.

Additional soil properties for non-uniform soils are entered in the application file (see Section 6.7.2).



Values for bulk density, soil disconnectedness, and effective porosity are specified for the entire soil column. A separate intrinsic permeability can be specified for each layer in the application file Section 6.7.2 (to do this, intrinsic permeability in the soil file must be set to zero). Also, values for organic carbon content, the cation exchange capacity, and the Freundlich exponent may be varied between soil layers by specifying ratios in the application file.

If separate intrinsic permeabilities are entered in the application file (see Section 6.7.2), a depth weighted average value is calculated for the hydrologic cycle (see Appendix A, Equation (3)). However, the individual values for intrinsic permeability are used for each layer in the pollutant cycle (see Appendix A, Section A2.5.2).

The bulk density, intrinsic permeability, and effective porosity are all interrelated parameters, yet only the intrinsic permeability can be varied from one layer to the next. Thus, if varying intrinsic permeabilities are used in the application file, the bulk density and effective porosity may not be appropriate for the resultant average permeability (see Equation A3).



6.6 Washload File Input Parameters

The washload file contains data used by SESOIL to calculate washload transport (the removal of the contaminant adsorbed to eroding soil particles). If you do not wish to simulate washload, you do not need to create the washload file, as this is an optional process.

Note that surface runoff, in which a dissolved contaminant may be transported as part of overland flow of rainwater, is simulated by SESOIL as part of the pollutant cycle only if the index of pollutant transport in surface runoff (ISRM in the application file) does not equal zero. Chemicals with high adsorption coefficients are likely to be transported as part of the eroding soil. A good introductory application may be found in Hetrick & Travis (1988).

To create and log a new washload input file follow these steps:


2. Create a new washload input file by saving the current (original) input file with the command.

3. Log the new washload input file in the journal.

4. Edit the new washload input file.



Parameter Description of the Washload Data Set


Description Description used to identify the washload data set. Limited to a maximum of 48 characters in length.

Parameters Washload Area

Units cm2

SESOIL Variable AWR

Description Area of the washload. The washload area should be equal to or less than the application area of the soil column (AR in the application file).

Source of Data Estimated based on site characteristics.

The washload area (AWR in the washload file) refers to a patch of topsoil subject to erosion. The areal extent of this patch can be smaller than or equal to the application area for the soil column (AR in the application file). The silt, sand, and clay fractions refer to the layer of topsoil. This topsoil specified in the washload file need not have the same properties as the upper layer of soil of the soil column. The washload option also requires information concerning the land over which the surface runoff and the washload will travel, including the length of the slope between the washload area and a barrier or sink into which the runoff will drain, and the average slope of the land.

Parameters Silt Fraction

Units fraction

SESOIL Variable

SLT

Description The fraction of silt in the washload topsoil.


Parameters Sand Fraction

Units fraction

SESOIL Variable

SND

Description The fraction of sand in the washload topsoil.




Parameters Clay Fraction

Units fraction

SESOIL Variable

CLY

Description The fraction of clay in the washload topsoil.


The sum of silt, sand and clay fractions must add up to 1.0.

Parameters Slope Length

Units cm

SESOIL Variable

SLEN

Description The slope length (length of travel) of the representative overland flow profile.


Parameters Land Slope

Units cm/cm

SESOIL Variable

SLP

Description The average slope over the representative overland flow profile.


Parameters Soil Erodibility Factor

Units tons/acre/English EI

SESOIL Variable

KSOIL

Description The soil erosion (erodibility) factor (tons/acre/English EI) used in the Universal Soil Loss Equation. This value typically ranges from 0.03 to 0.69; the default value is 0.23.




Parameters Soil Loss Ratio

Units unitless

SESOIL Variable

CFACT

Description The soil loss ratio used in the Universal Soil Loss Equation. The ratio depends on the type of ground cover and land management practices. Typical values range from 0.0001 (well managed land) to 0.94 (tilled soil). The default value of the soil loss ratio is 0.26.


Parameters Contouring Factor

Units fraction

SESOIL Variable

PFACT

Description The contouring factor for agricultural land. Typical contouring factors range from 0.1 (extensive practices) to 1.0 (no supporting practice). The default contouring factor value is 1.0.


Parameters Manning's Coefficient

Units unitless

SESOIL Variable

NFACT

Description Manning's coefficient for overland flow as used in the Universal Soil Loss Equation. This value typically ranges from 0.01 to 0.40; the default value is 0.03.


Examples of the washload parameters can be found in the CREMS model documentation (Knisel, 1980; Foster et al., 1980).

If only one year of washload data is entered, it will be used to generate the remaining years. If the number of years of available data is less than the number of years specified for the SESOIL run, the model will automatically use the last year of available data for all remaining years of the simulation.



6.7 Application File Input Parameters

The application file contains information describing the amount of contaminant released or applied to the soil column. The application file also includes specifications regarding the dimensions of the soil column, the thickness of the soil layers, and additional soil properties beyond those specified in the soil input file (e.g., pH). Vertical variation in soil properties are established as the ratio of the information contained in the soil and chemical files that apply to the uppermost layer. The user can tailor the application data for a particular site. Several years of chemical loading data may be entered into the soil column or the user may provide one year of data and specify that this year of data is to be used far all remaining years of the simulation. A description of the application input parameters is presented below.

To create and log a new application input file follow these steps:


2. Create a new application input file by saving the current (original) input file with the command.

3. Log the new application input file in the journal.

4. Edit the new application input file.



6.7.1 Column Parameters

Parameter Description of the Application Data Set


Description Description used to identify the application data set. Limited to a maximum of 48 characters in length.

Parameter Application Area

Units cm2

SESOIL Variable AR

Description The areal extent of contaminated soil in the SESOIL soil column. Note the default value is 100,000 cm2.

Source of Data The area of application is important when mass flux is entering groundwater is considered and should equal the areal extent of the contaminated soil.

The application area may be the area of a landfill, a chemical spill, or a field receiving a chemical application.

Parameter Latitude of Site

Units decimal degrees

SESOIL Variable L

Description The latitude of the site in decimal degrees. Latitude is used along with the climate parameters of temperature, relative humidity, short wave albedo and percent cloud cover to calculate evapotranspiration.

Source of Data Site location.

The latitude of the site is used in the calculation of potential solar radiation.

Parameter Continuous / Instantaneous Release (Spill Index)

Units unitless

SESOIL Variable ISPILL

Description Indicates if a contaminant load is instantaneous or a continuous load over each month. Set the spill index to 1 to model an instantaneous spill occurring at the beginning of the month. Set the spill index to 0 for a continuous loading rate occurring throughout the month.




If the spill index is to zero, then the monthly load is applied continuously in 30 equal parts, representing the 30 daily time steps of the month. If the spill index is set to 1, the load is applied in the first time step (day) of the month. See Appendix A, Section A2.5.2 for more details.

SESOIL allows the user to specify either continuous or instantaneous release, as discussed above. Instantaneous releases assume that the total mass is loaded during the first day of the month, and can be used to simulate a spill load. However, this option applies only to the first layer. The continuous load (where the load is divided into 30 daily loads, for each month) is always used for layers 2, 3, and/or 4 even if the spill index is set to 1. See Appendix A, Section A2.5.2 for more details.

Parameter Number of Soil Layers

Units unitless

SESOIL Variable

ILYS

Description Establishes the number of soil layers in SESOIL. The number of layers can be set from 2 to 4.

Source of Data Site-specific.

Parameters Layer Thickness

Units cm

SESOIL Variables

D1, D2, D3 and D4

Description Thickness of the SESOIL layers.


Parameters Number of Sub-Layers per Layer

Units unitless

SESOIL Variables

NSUB1, NSUB2, NSUB3 and NSUB4

Description The number of sub-layers in each SESOIL layer. The number of sub-layers can be set from 1 to 10. SESOIL will divide each layer into the appropriate number of sub-layers of equal thickness. Each sub-layer will have the same properties as the layer in it resides.




6.7.2 Ratio Parameters

Parameters pH of each Layer

Units pH

SESOIL Variables PH1, PH2, PH3 and PH4

Description The pH of each SESOIL soil layer.


The pH parameter is only used if the hydrolysis algorithm is utilized. Thus, if neutral hydrolysis, acid hydrolysis and base hydrolysis rates are set to zero in the chemical input file, you can ignore the pH values for the layers.

Parameters Intrinsic Permeability

Units cm2

SESOIL Variables K11, K12, K13 and K14

Description The intrinsic permeability for each SESOIL layer.

Source of Data Field measurements (slug test, pump tests), geotechnical analysis or estimated based on soil type.



The intrinsic permeability (K1 in the soil file) must be set to zero, for the varying intrinsic permeabilities entered in the application data to be used. If the intrinsic permeability in the soil data is not zero then the varying intrinsic permeabilities entered in the application data are ignored, and should be set to zero. Refer to Appendix A, Sections A2.3, A2.5.2, and A2.5.9 for a description regarding the uses of permeabilities in SESOIL.

Parameters Ratio of liquid phase biodegradation to upper layer

Units fraction

SESOIL Variables KDEL2, KDEL3 and KDEL4

Description The ratio of liquid phase biodegradation between the upper soil layer (KDEL in the chemical data) and the lower layers.

Source of Data Geotechnical analysis or estimated based on site characteristics.

For most model runs, the user will use 1.0 for the layer ratios of liquid phase biodegradation, solid phase biodegradation, organic carbon content, cation exchange capacity and Freundlich exponent.

Parameters Ratio of solid phase biodegradation to upper layer

Units fraction

SESOIL Variables KDES2, KDES3 and KDES4

Description The ratio of solid phase biodegradation between the upper soil layer (KDES in the chemical data) and the lower layers.


For example, the liquid phase biodegradation in layer 2 is computed as KDEL2 x KDEL where KDEL is input in the chemical file.

Parameters Organic carbon ratio to upper layer

Units fraction

SESOIL Variables OC2, OC3 and OC4

Description The ratio of the organic carbon content between the upper soil layer (OC in the soil data) and the lower layers.


The organic carbon ratios are only used if the soil partition coefficient (K in the chemical file) is set to zero. This causes SESOIL to compute soil the partition coefficient using the organic carbon adsorption coefficient (KOC from the chemical data) and the organic carbon content (OC from the soil file or the ratios in the application data).

The organic carbon content of native soil typically decreases with depth.



Parameters Cation exchange ratios to upper layer

Units Fraction

SESOIL Variables

CEC2, CEC3 and CEC4

Description The ratio of the cation exchange capacity between the upper soil layer (CEC in the soil data) and the lower layers.


Parameters Freundlich exponent ratio to upper layer

Units Fraction

SESOIL Variables

FRN2, FRN3 and FRN4

Description The ratio of the Freundlich exponent between the upper soil layer (FRN in the soil data) and the lower layers.


For example, the Freundlich exponent layer 2 is computed as FRN2 x FRN where FRN is input in the soil file.

Parameters Adsorption coefficient ratio to upper layer

Units Fraction

SESOIL Variables

ADS2, ADS3 and ADS4

Description The ratio of the adsorption coefficient between the upper soil layer and the soil partition coefficient (K in the chemical data) and the lower layers.


If the organic carbon adsorption coefficient (KOC from the chemical file) is used, the adsorption ratios (ADS2, ADS3 and ADS4) should be set to 1.0 since organic carbon adsorption coefficient (Koc) does not change. The calculated soil partition coefficient (Kd) is dependent on the organic carbon content (see OC2, OC3, and OC4 above). If Kd (K from the chemical file) is used, the values can be varied with the ratios ADS2 ADS3, and ADS4.



6.7.3 Contaminant Load Parameters

Parameters Contaminant Load (POLIN)

Units µg/cm2/month

SESOIL Variables POLIN# # indicates the layer number

Description The monthly contaminant load (mass per unit area) entering the top of each soil layer. If an initial soil-sorbed concentration is desired, a contaminant load may be applied at the beginning of the first month of the first year to create the initial condition. The contaminant load is calculated using the following equation:

RSDCONCPOLIN ××= where:

Parameter Description POLIN The contaminant load to apply in µg/cm2/month, CONC The concentration sorbed to the soil in µg/g (ppm), D The thickness of the layer in centimeters which the

contaminant is applied (D1, D2, D3 and D4), and RS The soil bulk density of the soil in g/cm3.




You can also use the sub-layer concentration load option, which is much easier to use.

Contaminant loads in each layer are applied to the uppermost sub-layer.

Although each sub-layer has the same soil properties as the major soil layer in which they reside, the resulting chemical concentrations in each sub-layer will be different.

SESOIL requires that data on contaminant release be expressed as a monthly load. This loading may enter into any of the soil layers, or may enter the uppermost layer via rainfall. When a layer is broken into sub-layers, SESOIL assumes that the chemical loading enters the top sub-layer and is immediately spread throughout this sub-layer. If a layer has only one sub-layer the load is immediately spread throughout the entire layer.

See Appendix A, Section A2.5.2 for an explanation of how the contaminant depth is computed after the contaminant is loaded into a sub-layer.

If the spill index (ISPILL) is zero, the monthly load is released in 30 equal portions for each day of the month. If the spill index is set to 1, the entire monthly load is released during the first day of the month. See Section A2.5.2 for additional information on the release rates.

Parameters Mass of Contaminant Transformed (TRANS)

Units µg/cm2/month

SESOIL Variables

TRANS# # indicates the layer number

Description The monthly mass of contaminant transformed in each layer by a process not otherwise included in SESOIL.

Source of Data Site measurements or estimated based on site characteristics.

The parameters for contaminant transformed and contaminant removed (TRANS# and SINK#) are means for the user to incorporate transformation and transport processes not specifically included in the SESOIL program. These parameters may be specified for each of the soil layers.

Parameters Mass of Contaminant Removed (SINK)

Units µg/cm2/month

SESOIL Variables

SINK# # indicates the layer number

Description The monthly mass of contaminant removed from each layer by a process not otherwise included in SESOIL. An example could include an estimated of the amount of chemical lost from the soil column due to lateral flow.




Parameters Ligand Load (LIG)

Units µg/cm2/month

SESOIL Variables

LIG# # indicates the layer number

Description The monthly ligand load input into each layer.


When simulating a contaminant which undergoes complexation, the user must also provide a loading rate for the ligand which becomes part of the complex (LIG#).

Parameters Volatilization / Diffusion Index (VOLF)

Units Fraction

SESOIL Variables

VOLF# # indicates the layer number

Description The index of volatilization/diffusion upward from a soil layer. Values range from 0.0 to 1.0. A volatilization index of 0.0 means there will be no volatilization/diffusion upward from the soil layer. A volatilization index of 1.0 means 100 percent of the estimated volatilization/diffusion will simulated for the soil layer. A volatilization index of 0.5 specifies that 50 percent of the estimated volatilization/diffusion will be simulated from the soil layer. See Appendix A, Section A2.5.3 for additional information on volatilization.


Parameters Index of Contaminant Transport in Surface Runoff (ISRM) Units Fraction SESOIL Variable ISRM Description The index for contaminant transport in surface runoff. Index values

may range from 0.0 to 1.0. ISRM is the ratio of the contaminant concentration in the surface runoff to the dissolved concentration in the top sub-layer of the top soil layer. A contaminant transport index of 0.0 means no contaminant transport will occur in the surface runoff. A contaminant transport index of 0.40 specifies that the contaminant concentration in surface runoff is 0.40 times the concentration in the soil moisture of the top soil sub-layer. A contaminant transport index of 1.0 establishes a one to one ratio between the contaminant concentration in surface runoff and soil moisture in the top sub-layer (see the Washload data and Appendix A, Section A2.5.7 for additional information).




Parameters Ratio of Contaminant Concentration in Rain to Water Solubility (ASL)

Units Fraction

SESOIL Variable

ASL

Description Contaminant load contained in the monthly precipitation. The load is determined by the ratio of the contaminant concentration in precipitation to the contaminant's maximum solubility in water. The contaminant load to the top soil layer is determined by the contaminant concentration ratio (ASL) multiplied by the water solubility (SL in the chemical data) and the infiltration rate computed by the hydrologic cycle.


SEVIEW displays two years of application data. This was done as SESOIL uses the second year data for all subsequent years of the simulation. For contaminant spills a load is typically entered only during the first month of the first year in the application file to establish the observed soil contaminant concentration. Using this approach no contaminant load is established in the second year.

SESOIL uses the final year of application data for all subsequent years.

If the organic carbon adsorption coefficient (KOC from the chemical file) is used, the adsorption ratios (ADS2, ADS3 and ADS4) should be set to 1.0 since organic carbon adsorption coefficient (Koc) does not change. The calculated soil partition coefficient (Kd) is dependent on the organic carbon content (see OC2, OC3, and OC4 above). If Kd (K from the chemical file) is used, the values can be varied with the ratios ADS2 ADS3, and ADS4.



6.7.4 Sub-Layer Load Parameters

Parameters Contaminant Sub-Layer Load (CONCIN)

Units (µg/g)/month

SESOIL Variables CONCIN###

### indicates the layer and sub-layer numbers

Description The monthly contaminant load in ppm [(µg/g)/month] for each sub-layer. If an initial soil-sorbed concentration is desired, a contaminant concentration it is applied at the beginning of the first month of the first year to create the initial condition.




6.7.5 SUMMERS Model Parameters

Parameters Saturated Hydraulic Conductivity (SATCON) Units cm/sec

SESOIL Variable SATCON

Description Horizontal hydraulic conductivity of the saturated porous medium.

Typical Values Clay 1x10-6 cm/sec Silt 1x10-6 - 1x10-3 cm/sec

Silty sand 1x10-5 - 1x10-1 cm/sec Clean gravel 1x10-3 - 1 cm/sec

Gravel > 1 cm/sec Source of Data Pump tests or slug tests or estimated values based on soil type.

Parameters Hydraulic Gradient (HYDRA) Units ft/ft

SESOIL Variable HYDRA

Description The slope of the potentiometric surface. In unconfined aquifers, this is equivalent to the slope of the water table.

Typical Values 0.0001 - 0.05 ft/ft

Source of Data Determined from potentiometric surface maps of the static water level data from monitoring wells.



Parameters Thickness of Groundwater Mixing Zone (THICKS)

Units cm

SESOIL Variable THICKS

Description The thickness of the groundwater mixing zone along the z-axis.

Typical Values 1 to 20, Site-specific

Source of Data Based on site aquifer characteristics or regulatory requirements.

Parameters Source Width Perpendicular to Groundwater Flow (WIDTH)

Units cm

SESOIL Variable WIDTH

Description The width of the contaminant release along the y-axis (perpendicular to groundwater flow).

Typical Values Site-specific

Source of Data Based on geometry of the site contamination.

Parameters Background Concentration in Groundwater (Summers)

Units µg/ml

SESOIL Variable BACKCA

Description Background contaminant concentration in groundwater upgradient of the SESOIL load.





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7.1 Introduction

BIOSCREEN is screening level groundwater transport model that simulates RNA of dissolved hydrocarbons. It is written in the Microsoft Excel and Microsoft Visual BASIC languages. BIOSCREEN can simulate RNA based on advection, dispersion, adsorption, and biological decay (both aerobic and anaerobic) and is based on the Domenico model. BIOSCREEN contains three models that simulate RNA as:

1. Contaminant transport without decay,

2. Contaminant transport with biodegradation simulated as a first order decay process,

3. Contaminant transport with biodegradation simulated as an instantaneous reaction.

The SEVIEW parameters for BIOSCREEN contain information describing the chemical, soil and contaminant load. These include the organic carbon coefficient, decay coefficient, organic carbon content, effective porosity, soil bulk density, permeability, maximum leachate concentration, width of the SESOIL contaminant release and the groundwater dilution factor. SEVIEW can also be used to calibrate the BIOSCREEN source half life to the SESOIL leachate load to groundwater. This section provides a description of each BIOSCREEN parameter linked to SESOIL. Additional information on the parameters is provided in the BIOSCREEN User’s Manual (Newell et. al., 1997).

The data in the SEVIEW parameters for BIOSCREEN are updated whenever you preview or print a SESOIL Pollutant Cycle Report (Section 5.2.4.3.4).

7.2 Establish SESOIL Parameters to Transfer to BIOSCREEN

When you click on the Establish Default BIOSCREEN Data in the navigator or select the Establish SESOIL Parameters to Transfer to BIOSCREEN in the menu, the following window is displayed. To select data to be transferred simply click on the check box associated with the parameter. Parameters that are selected for transfer are identified with a check mark in the check box. The Establish Default BIOSCREEN Input Parameters is separated into the Input, Load and Dilution Factor Parameters screen tabs. A description of each parameter is presented below.



7.2.1 BIOSCREEN Input Parameters

7.2.1.1 Chemical Parameters

Data parameters are deselected by clicking on the check box a second time.

7.2.1.1.1 SESOIL Chemical Name Description SEVIEW can transfer the chemical name description from the SESOIL chemical data set, by placing a check mark for the SESOIL Chemical Name Description. The chemical description will be placed in the second line of the project description in the BIOSCREEN spreadsheet.

7.2.1.1.2 SESOIL Organic Carbon Partition Coefficient (Koc) To transfer the organic carbon adsorption coefficient of a chemical from SESOIL, place a check mark in the box for the SESOIL Organic Carbon Partition Coefficient (Koc) option. SEVIEW will transfer the Koc (KOC) value entered in the SESOIL chemical data set to the BIOSCREEN Partition Coefficient input.

If the adsorption coefficient on soil (K), was entered instead of the Koc value in the SESOIL chemical file, a zero will be entered in the BIOSCREEN spreadsheet.



7.2.1.1.3 SESOIL First Order Liquid Phase Decay Coefficient

The first order liquid phase decay coefficient rate of the substance per year will be transferred to BIOSCREEN by placing a check mark in the SESOIL First-Order Liquid Phase Decay Coefficient (KDEL) check box.

SEVIEW converts the first order liquid phase decay coefficient rate entered in the SESOIL chemical file from 1/day to 1/year prior to transferring the value to BIOSCREEN.

7.2.1.2 Soil Parameters

7.2.1.2.1 SESOIL Uppermost Soil Layer Organic Carbon Content

To transfer the organic carbon content, place a check mark in the SESOIL Select the Uppermost Soil Layer Organic Carbon Content (foc) check box. SEVIEW will transfer the organic carbon content (OC) in the SESOIL soil input file to the Fraction Organic Carbon cell in BIOSCREEN.

SEVIEW converts the percent organic carbon content value to the fraction organic carbon content (foc) prior to transferring the value.

7.2.1.2.2 SESOIL Effective Porosity The effective porosity for the SESOIL soil column is transferred by placing a check mark in the SESOIL Effective Porosity check box. When selected, SEVIEW will transfer the effective porosity (N) entered in the SESOIL soil data set to the BIOSCREEN Porosity cell.

The effective porosity values used in SESOIL should be used with caution, as the porosity values used in SESOIL may be higher than those typically used in BIOSCREEN and other models for the same soil type.

7.2.1.2.3 SESOIL Soil Bulk Density SEVIEW can transfer the average dry soil bulk density (RS) in the SESOIL soil data set. The soil bulk density is transferred by placing a check mark in the SESOIL Soil Bulk Density check box.

7.2.1.2.4 SESOIL Permeability The average soil permeability (K1) in the SESOIL soil data set is transferred by placing a check mark in the SESOIL Permeability check box.

If the soil permeability (K1) is set to zero and layer-specific permeability values are entered in the SESOIL Application File, SEVIEW will transfer the permeability of the lowermost soil layer (K11, K12, K13 or K14).

SEVIEW converts intrinsic permeability to cm/sec by multiplying by 1x105 prior to transferring the data.



7.2.1.3 Auto Save

7.2.1.3.1 Save BIOSCRN4.XLS Using the SESOIL Output File Name SEVIEW can automatically save the BIOSCREEN workbook using the SESOIL output file name with an .XLS extension in the current directory, by placing a check mark in the save BIOSCRN4.XLS Using the SESOIL Output File Name check box.

The user must reopen the original BIOSCRN4.XLS file prior to transferring the next SESOIL scenario data, if the auto save option is used.

7.2.2 BIOSCREEN Load Parameters

7.2.2.1 Load Options

7.2.2.1.1 Transfer Maximum SESOIL Leachate Concentration SEVIEW will transfer the maximum SESOIL leachate concentration to BIOSCREEN by placing a check mark in the Transfer Maximum SESOIL Leachate Concentration check box. SEVIEW determines the SESOIL leachate concentration by dividing the monthly mass entering groundwater GWR. RUNOFF by the monthly infiltration rate GRW. RUNOFF (CM) times the areal extent of the application (AR).



Prior to transferring the maximum SESOIL leachate concentration, SEVIEW can apply a groundwater mixing zone dilution factor (DF) (see Section 7.2.3).

7.2.2.1.2 Transfer the Width of SESOIL Column

By placing a check mark in the Transfer the Width of SESOIL Column check box SEVIEW will transfer the width of the SESOIL soil column in the y-direction as the source width. If the Width of SESOIL Column check box is not checked the value entered into BIOSCREEN will be used.

7.2.2.2 Source Half life Options

SEVIEW provides you with four BIOSCREEN source half life options. A description of each is presented below.

7.2.2.2.1 Calibrate BIOSCREEN Source Half life to SESOIL Load When you check the Calibrate BIOSCREEN Source Half life to SESOIL Load box, SEVIEW will calibrate the BIOSCREEN source half life rate, for the No Degradation and First-order Decay models, to the half life rate of the mass leaching to groundwater predicted by SESOIL. This establishes a declining source concentration in BIOSCREEN that is identical to the time dependent load from SESOIL. The source half life rate for the load to groundwater from SESOIL is determined as difference in years between the month of the maximum leachate concentration and the first month with half or less than half of the maximum concentration.

If the load to groundwater can not be described as a first-order decay rate, SEVIEW will inform the user that the BIOSCREEN half life can not be calibrated and that either the Transfer SESOIL Mass Load to Groundwater or the Establish “Infinite” BIOSCREEN Source Mass source half life options should be used.

The BIOSCREEN source half life term applies only to the source and is not associated with the First-order Decay model half life rate.

As the BIOSCREEN half life rate can not be directly entered into, SEVIEW calibrates the mass load to establish a source half life rate based on the following equation:

MQ C L

o

o=

× × 12

0 693.

where:

Parameter Description Mo Mass required to establish the source half life rate based on the SESOIL

load at time zero (mg) Q Groundwater flow rate through source area (L/year) Co Maximum SESOIL leachate concentration (plus the biodegradation

capacity for instantaneous reaction model) at time zero (mg/L) L1

2 Half life rate of the SESOIL load to groundwater (years)



BIOSCREEN also establishes a separate source half life rate for the Instantaneous Reaction model. Two separate source half life terms are used as in the No Degradation and First-order Decay models simulate biodegradation immediately downgradient of the source, but not at the source. Where as, the Instantaneous Reaction model includes biodegradation at the source. This means that the Instantaneous Reaction model half life rates will be smaller (see The BIOSCREEN User’s Guide and Newell et. al., 1995).

7.2.2.2.2 Transfer SESOIL Mass Load to Groundwater Place a check mark in the Transfer SESOIL Mass Load to Groundwater check box to transfer the total mass of a substance entering groundwater as predicted by SESOIL into the BIOSCREEN Soluble Mass cell. The mass entering groundwater is the total sum of the mass leaving the bottom of the soil column (GWR. RUNOFF) for the length of the SESOIL model run.

Prior to transferring the data SEVIEW will convert mass from µg to kg.

BIOSCREEN will calculate a source half-life value when a value is entered into the Soluble Mass cell (See the BIOSCREEN User’s Manual pages 30 through 32 for additional information).

7.2.2.2.3 Establish “Infinite” BIOSCREEN Source Mass SEVIEW will transfer an “Infinite” mass to BIOSCREEN if you select this option. The word “Infinity” will be placed in the Soluble Mass cell to set an infinite mass.

7.2.2.2.4 Do Not Alter the BIOSCREEN Half life Data SEVIEW will not transfer anything to the BIOSCREEN Soluble Mass cell if you select this option.

7.2.3 Dilution Factor Parameters

Prior to inserting the maximum SESOIL leachate concentration, SEVIEW can apply a groundwater mixing zone dilution factor (DF). If a � is placed in the Apply Dilution Factor to SESOIL Leachate Concentration check box, SEVIEW will apply a dilution factor to the maximum SESOIL leachate concentration. SEVIEW also transfers the calculated dilution factor and original SESOIL leachate concentration to the BIOSCREEN spreadsheet below the SOURCE DATA section of the BIOSCREEN input screen. A description of the dilution factor parameters is presented below. The dilution factor is determined using the following equation:

DFK i d

R L= + × ×

×1



where:

Parameter Description DF Dilution factor (unitless) K Aquifer hydraulic conductivity (cm/sec) I Hydraulic gradient (ft/ft) D Thickness of groundwater mixing zone (ft) R Infiltration rate (cm/month) L Source length parallel to ground water flow (ft)

Parameter Hydraulic Conductivity

Units cm/sec


Typical Values Clays: Silts: Silty sands: Clean sands: Gravels:

<1x10-6 cm/sec 1x10-6 - 1x10-3 cm/sec 1x10-5 - 1x10-1 cm/sec 1x10-3 - 1 cm/sec > 1 cm/sec

Source of Data Pump tests or slug tests or estimated values based on soil type. SEVIEW Link Place a � in the SESOIL Permeability check box to use the SESOIL

value for permeability. SEVIEW will use the soil permeability from the soil input file (K1) or the lowermost permeability in the SESOIL application file if K1 is zero. If the check box is not marked the Hydraulic Conductivity value entered here will be used.

SEVIEW converts the intrinsic permeability used in SESOIL to cm/sec.



Parameter Hydraulic Gradient

Units ft/ft




Parameter Groundwater Recharge Rate

Units cm/month

Description The monthly groundwater recharge. If a � is placed in the SESOIL Recharge Rate SEVIEW will use the predicted recharge rate associated with the maximum leachate concentration.


Source of Data Determined based on modeling or often estimated using soil type.

Parameter Source Length Parallel to Groundwater Flow

Units ft

Description The length of the contaminant release along the x-axis (parallel to groundwater flow). If a � is placed in the SESOIL Column Width SEVIEW will transfer the length of the SESOIL soil column in the z-direction as the source width. If the SESOIL Column Width check box is not checked the value entered into source length will be used.


Source of Data Based on geometry of the site contamination.

Parameter Thickness of Groundwater Mixing Zone

Units ft

Description The thickness of the groundwater mixing zone along the z-axis. If the Calculate Mixing Depth check box is not checked the value entered into the Thickness of Groundwater Mixing Zone will be used. If a � is placed in the Calculate Mixing Depth check box SEVIEW will calculate a groundwater mixing zone thickness using the following equation:



d dLR

Kida

a

= + − −��

�

��

�

�

��

��

��

0 0112 1. exp

Where:

Parameter Description d 7.2.3.1.1.1.1.1.1 Mixing zone depth L Source length parallel to groundwater

flow

R Infiltration rate K Aquifer hydraulic conductivity i Hydraulic gradient da Aquifer thickness



Parameter Aquifer Thickness

Units ft

Description The thickness of the aquifer along the z-axis. This value is only used if a � is placed in the Calculate Mixing Depth check box.



7.3 Get BIOSCREEN Data

This command reads BIOSCREEN input parameters and converts the data in to an AT123D input file. The AT123D model requires two additional parameters not used by BIOSCREEN. The first is the x-axis coordinate of the contaminant release. The BIOSCREEN model assumes an infinite release in the x direction. The other is the water diffusion value for the contaminant. The x-axis coordinate of the contaminant release is based on results of the site investigation. Water diffusion values are readily available in the chemical literature and many agencies have compiled a list of values for the most common contaminants.



Parameter Starting Coordinate of the Source in the X-Direction

Units ft

AT123D Variable RL1

Description Starting coordinate of the source in the x-direction.


Parameter Water Diffusion Coefficient Units cm2/sec

AT123D Variable AMTAU

Description Water diffusion coefficient multiplied by tortuosity.





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8.1 Introduction

This section provides a detailed description of each AT123D input parameter. The AT123D input file parameters are divided into the Aquifer, Input and Output data sets. A description of the input parameters for each section is provided below.

An AT123D input file is created whenever you preview or print a SESOIL Pollutant Cycle Report.

8.2 AT123D Aquifer Parameters

The AT123D aquifer parameters contain information describing the soil characteristics and aquifer geometry. This includes hydraulic conductivity, hydraulic gradient, effective porosity, soil bulk density longitudinal, transverse and vertical dispersivities, aquifer width and depth, the number of eigenvalues and the model steady state tolerance factor.

The following descriptions also apply to the Establish Default AT123D Input Parameters window. The Establish Default AT123D Input Parameters window is opened by clicking on the Establish Default AT123D Data command in the navigator or by selecting the Set Default AT123D Values in the main menu.



The Establish Default AT123D Input Parameters window looks very much like the input screen, except some of the parameters are followed by check boxes. If a check box is not marked, SEVIEW will use the value entered in the parameter when creating an AT123D input file. If a check box is mark, SEVIEW will use the value entered in SESOIL when creating an AT123D input file.

Note: AT123D input files are created whenever you preview or print a Pollutant Cycle Report.

Parameter Hydraulic Conductivity

Units meters/hour

AT123D Variable

HCOND



<3.6x10-5 m/hr 3.6x10-5 - 3.6x10-2 m/hr 3.6x10-4 - 3.6 m/hr 3.6x10-2 - 36 m/hr > 36 m/hr


Source of Data Pump tests or slug tests or estimated values based on soil type.

SEVIEW Link Place a � in the Permeability check box to use the SESOIL value for permeability. SEVIEW will transfer the soil permeability from the soil input file (K1) or the lowermost permeability in the SESOIL application file if K1 is zero. If the use SESOIL permeability box is not checked the value entered will be used.

SEVIEW converts the intrinsic permeability used in SESOIL to m/hr prior to transferring the value to AT123D.

Parameter Hydraulic Gradient

Units meter/meter

AT123D Variable

HGRAD

Description The slope of the potentiometric surface. In unconfined aquifers, this is equivalent to the slope of the water table. Assumed to be along the longitudinal direction (x-axis)

Typical Values 0.0001 - 0.05 m/m




Parameter Effective Porosity

Units dimensionless

AT123D Variable

POR

Description Dimensionless ratio of the volume of interconnected voids to the bulk volume of the aquifer matrix. Note that “total porosity” is the ratio of all voids (included non-connected voids) to the bulk volume of the aquifer matrix. Difference between total and effective porosity reflect lithologic controls on pore structure. In unconsolidated sediments coarser than silt size, effective porosity can be less than total porosity by 2-5% (e.g. 0.28 vs., 0.30) (Smith and Wheatcraft, 1993).

Typical Values Clay 0.01 - 0.20 Sandstone 0.005 - 0.10 Silt 0.01 - 0.30 Unfract. Limestone 0.001 - 0.05 Fine Sand 0.10 - 0.30 Fract. Granite 0.00005 - 0.01 Medium Sand 0.15 - 0.30 Coarse Sand 0.20 - 0.35 Gravel 0.10 - 0.35 (From Wiedemeier, Wilson, et al.,

1995; originally from Domenico and Schwartz, 1990 and Walton, 1988).

(From Domenico and Schwartz, 1990)

Commonly used value for silts and sands is an effective porosity of 0.25.


SEVIEW Link The effective porosity for the SESOIL soil column (N in the SESOIL soil input file) if a � is placed in the Porosity check box. If the SESOIL Porosity box is not checked the value entered will be used.

Parameter Soil Bulk Density

Units kilogram/meter3

AT123D Variable RHOB

Description Bulk density of the aquifer matrix.

Typical Values Typical values for soil bulk density in kilogram/meter3.

Clay 1,400 - 2,200 Silt 1,290 - 1,800 Sand 1,180 - 1,580

Source of Data Obtained from geotechnical laboratory analysis of soil samples or estimated values based on soil type.

SEVIEW Link The average dry soil bulk density (g/cm3) converted to kilogram/meter3 for the entire soil column (RS in the SESOIL soil input file) if a � is placed in the Bulk Density check box. User defined value if a � is placed in the Bulk Density check box.



Parameter Longitudinal Dispersivity, ααααL Transverse Dispersivity, ααααT Vertical Dispersivity, ααααV

Units meters

AT123D Variables

AELONG, ATRANV and AVERTI

Description The process whereby a plume will spread out in a longitudinal direction (along the direction of groundwater flow), transversely (perpendicular to groundwater flow), and vertically downwards due to mechanical mixing in the aquifer and chemical diffusion.

Typical Values Selection of dispersivity values is a difficult process, given the impracticability of measuring dispersion in the field. Typically estimated based on site characteristics. Methods to establish dispersivities based on contaminant plume length (Lp) are presented below: Longitudinal Dispersivity (ααααL)

( ){ } 414.210log83.0 pL L×=α (Xu and Eckstei(Xu & Eckstein, 1995)

Note: Lp is in meters Transverse Dispersivity (ααααT)

(αT) = 0.10 (αL) Gelhar et al., 1992 in BIOSCREEN, 1996

Vertical Dispersivity (ααααV) (αV) = very low (i.e. 1 x 10-99 ft) BIOSCREEN, 1996

Other commonly used relationships include: αL = 0.1 Lp (Pickens and Grisak, 1981)

αT = 0.33 αL (ASTM, 1995) (EPA, 1986) αV = 0.05 αL (ASTM, 1995)

αV = 0.025αL to 0.1 αL (EPA, 1986)

Source of Data Typically estimated using the relationships provided above.

SEVIEW Link User defined.

Parameter Aquifer Width

Units meters

AT123D Variable WIDTH

Description Aquifer width in the y-direction. Note: This value is ignored if the Infinite Width �� check box is selected.


SEVIEW Link Default value set by the user.



Parameter Infinite Width

AT123D Variable

IWID

Description Parameter specification indicating if the aquifer is infinitely wide (y-direction).

Options � - Yes � - No

SEVIEW Link Default option of � or established by the user.

Parameter Aquifer Depth

Units meters

AT123D Variable

DEPTH

Description Aquifer depth in the z-direction from below the water table.

Note: This value is ignored if the Infinite Depth �� check box is selected.


SEVIEW Link Default value set by the user.

Parameter Infinite Depth

AT123D Variable

IDEP

Description Parameter specification indicating if the aquifer is infinitely deep (z-direction).

Values � - Yes � - No

SEVIEW Link Default option of � or established by the user.

Aquifer boundaries located at infinity are easier to calculate than those of finite width or depth are. Thus, if the aquifer boundaries are relatively large in relation to the size of the source area or if the distance from the source to the area of interest is large, an infinite aquifer along either or both the x- or y- directions may be best.



Parameter Number of Eigenvalues AT123D Variable

NROOT

Description The number of eigenvalues establishes the maximum number of terms that will be calculated for a series solution before truncation occurs.

Typical Values Start with 500 and increase it to a 1000 if a warning message is printed out with the solution. The eigenvalues value may not exceed 1000.

SEVIEW Link The default value is 500.

Parameter Model Error Tolerance AT123D Variable

ACCU

Description Error tolerance if steady-state solution is desired.

Typical Values 0.01 to 0.001

SEVIEW Link Default of 0.001 or user defined.

8.3 AT123D Input Parameters

The AT123D Input parameters contain information describing the geometry of the source release and the contaminant properties. Input parameters include the starting and ending coordinates of the release, the chemical distribution coefficient, water diffusion coefficient and the first-order decay coefficient.



Parameter Description of the AT123D Scenario

AT123D Variable

TITLE

Description The title description for the model scenario

SEVIEW Link The text entered in the AT123D title or the first 80 characters of the SESOIL description if the AT123D description was not modified.

8.3.1 AT123D Release Coordinates

Parameter Starting Coordinate of the Source in the X-Direction

Units meters

AT123D Variable

RL1

Description Starting coordinate of the source in the x-direction.


SEVIEW Link Set by SEVIEW to the width of the SESOIL soil column (AR) centered at x = 0 and y = 0 if a � is placed in the Column Width check box.

User defined value if a � is placed in the Column Width check box.

Remember the total area should equal the area of the SESOIL soil column.

Parameter Ending Coordinate of the Source in the X-Direction

Units meters

AT123D Variable

RL2

Description Ending coordinate of the source in the x-direction.


SEVIEW Link Set by SEVIEW to the width of the SESOIL soil column (AR) centered at x = 0 and y = 0 if a � is placed in the Column Width check box.

User defined value if a � is placed in the Column Width check box.



Parameter Starting Coordinate of the Source in the Y-Direction

Units meters

AT123D Variable

RB1

Description Beginning coordinate of the source in the y-direction.


SEVIEW Link Set by SEVIEW to the width of the SESOIL soil column (AR) centered at x = 0 and y = 0 if a � is placed in the Column Depth check box.

User defined value if a � is placed in the Column Depth check box.

Parameter Ending Coordinate of the Source in the Y-Direction

Units meters

AT123D Variable

RB2

Description Ending coordinate of the source in the y-direction.


SEVIEW Link Set by SEVIEW to the width of the SESOIL soil column (AR) centered at x = 0 and y = 0 if a � is placed in the Column Depth check box.

User defined value if a � is placed in the Column Depth check box.

Parameter Starting Coordinate of the Source in the Z-Direction

Units meters

AT123D Variable

RH1

Description Beginning coordinate of the source in the z-direction.


SEVIEW Link SEVIEW establishes a default value of zero, or user defined.



Parameter Ending Coordinate of the Source in the Z-Direction

Units meters

AT123D Variable

RH2

Description Ending coordinate of the source in the z-direction.


SEVIEW Link SEVIEW establishes a default value of zero, or user defined.

The user should experiment with varying AT123D source configurations to determine the best approach. Some guideline regarding the relationship between the source area and aquifer dimensions are presented below.

• For scenarios where the source area is relatively small and the point of compliance is relatively distant may be modeled as a point source. The validity of this approach depends on the relative scale between the source dimensions and the distance to the point of compliance.

• Contaminant loads from injection wells can be simulated as a line source in the z-direction. Where the starting and ending coordinates in the z-direction (RH1 and RH2) define the top and bottom of the screened interval of the well.

• Contaminant loads from shallow trenches that do not penetrate below the water table may be simulated as a line source in along either the x- or y-axis.

• Contaminant loads that do not penetrate very far into the water table can be simulated as a plane source on the surface of the groundwater. This approach should provide a conservative estimate of contaminant concentrations, as limited dilution due to dispersion can occur. Depending on load dimensions the user may also establish a line source at the top of the water table, oriented perpendicular to groundwater flow.

• Contaminant spills that occurred over a relatively short time span may be simulated using an instantaneous source. However, if the user is interested in predicted contaminant concentrations over a relatively short period of time a continuous source may provide better results.

• Contaminant sources that are not aligned along the x or y axis can be simulated using the width of the source perpendicular to groundwater flow. As with the other methods the user should try varying contaminant load dimensions to identify the best fit.

• Irregularly shaped contaminant loads can be separated into several smaller loads and solved independently. The results must then be summed to establish predicted groundwater concentrations for each time step. As this is a very time-consuming process it should be only utilized for cases where maximum accuracy is called for.



8.3.2 AT123D Substance Parameters

Parameter Organic Carbon Content, OC

Units Percent

AT123D Variable

ROC

Description The organic carbon content of the saturated soil.


SEVIEW Link User defined value if a � is placed in the Soil Organic Carbon check box.

Parameter Organic Carbon Adsorption Coefficient, Koc


AT123D Variable

RKOC

Description The adsorption coefficient for the compound on organic carbon.


SEVIEW Link User defined value if a � is placed in the Carbon Adsorption Coeff. check box.

Parameter Distribution Coefficient, Kd

Units meters3/kilogram

AT123D Variable

AKD

Description Chemical-specific partition coefficient. Calculated by SEVIEW if the percent Organic Carbon Content and Organic Carbon Adsorption Coefficient are greater than 0.

Typical Values Chemical-specific and soil organic carbon specific.

SEVIEW Link Established by SEVIEW as the organic carbon partition coefficient (Koc) value times the fraction organic carbon (foc) in the bottom soil layer if a � is entered into the Distribution Coeff. (Koc * foc) check box. User defined value if a � is placed in the Distribution Coeff. (Koc * foc) check box.



Parameter Water Diffusion Coefficient Multiplied by Tortuosity

Units meters2/hour

AT123D Variable

AMTAU

Description Water diffusion coefficient multiplied by tortuosity.


You can select water diffusion coefficient values from the chemical database. The chemical database is opened by clicking on the command displayed next to the Water Diffusion Coefficient input parameter. The Water Diffusion Coefficient parameter is displayed at the lower left. To copy the Water Diffusion Coefficient data to the AT123D parameter move to

the desired chemical and click on the command and close the database window. If you do not want to update the AT123D data simply close the window. A copy of the chemical database screen is presented below.

SEVIEW converts the water diffusion coefficient in the chemical database from cm2/second to meters2/hour as the value is transferred.

The water diffusion coefficient was added to the SESOIL version 6.0 chemical input file. Remember, if you use an older version of the chemical file SESOIL 6.0 cannot transfer a water diffusion value to AT123D. Versions 2.1 and 3.0 of SESOIL simply ignore the water diffusion value.



Parameter First-Order Decay Coefficient, λλλλ

Units 1/hour

AT123D Variable RAMADA

Description Coefficient describing first-order decay rate for dissolved constituents.

Typical Values Chemical-specific

Source of Data Methods for selection of appropriate decay coefficients include: Literature Values: Published references are available listing decay half-life values for hydrolysis and biodegradation (e.g., see Howard et al., 1991). Many references report the half-lives; these values can be converted to the first-order decay coefficients using k = 0.693/t1/2.

Calibrate to Existing Plume Data: If the plume is in a steady-state or diminishing condition, AT123D can be used to determine first-order decay coefficients that best match the observed site concentrations. One may adopt a trial-and-error procedure to derive a best-fit decay coefficient for each contaminant. For still-expanding plumes, this steady-state calibration method may over-estimate actual decay-rate coefficients and contribute to an under-estimation of predicted concentration levels.

SEVIEW Link The liquid phase biodegradation rate of the compound (KDEL in the SESOIL chemical input file) if a � is entered into the First-Order Decay check box. User defined value if a � is placed in the First-Order Decay check box.

SEVIEW converts KDEL from units of 1/day to 1/hour prior to transferring the data.

8.3.3 AT123D Output Parameters

The AT123D Output parameters contain information that specifies contaminant concentrations at specific times and coordinates. Output parameters include the starting and ending points in time and the size of the time step. The output parameters also include information on the coordinates where the concentration will be determined in the x, y and z directions.



Parameter Starting Time Step

Units Months

AT123D Variable

NBGTI

Description The first month for which a solution is desired.

Typical Values 1 to 11,999 (one month to 1,000 years minus one month)

SEVIEW Link Set by SEVIEW as the starting month of the year with the initial groundwater load predicted by SESOIL if a � is entered into the Use starting year predicted by SESOIL check box.

User defined value if a � is placed in the Use starting year predicted by SESOIL check box.

Within AT123D time steps start with a value of 1 not 0, so you must a 1 to the starting and ending time steps (NBGTI and NEDTI).



Parameter Ending Time Step

Units Months

AT123D Variable

NEDTI

Description The final month for which the solution is desired.

Typical Values 2 to 11,999 (month 2 to 1,000 years).

SEVIEW Link Set by SEVIEW as the length of the SESOIL scenario in months, or user defined if a � is entered into the Use length of SESOIL scenario check box.

User defined value if a � is placed in the Use length of SESOIL scenario check box.

Parameter Time Step

Units months

AT123D Variable

NPRINT

Description The number of months between results presented in the AT123D output file.

Typical Values 1 - Monthly results

12 - Annual results

SEVIEW Link User defined.

Parameter X-Axis Coordinates

Units meters

AT123D

Variable

XDIM(I)

Description Coordinates in the x-direction (direction of flow), where the concentration is desired.

Typical Values The total distance in the x direction is often set to be slightly larger than the estimated final plume length or to the downgradient point of concern.3

3 Since AT123D is an analytic program, you do not need a dense grid network (nodes) to

calculate contaminant concentrations. This means that each nodes concentration is determined independently and is not dependent on the surrounding nodes. Thus, contaminant concentrations need only be calculated where the solution is desired.



Parameter Y-Axis Coordinates

AT123D Variable

YDIM(I)

Units meters

Description Coordinates in the y-direction (horizontally perpendicular to flow), where the concentration is desired.

Typical Values The total distance in the y direction is often set to be slightly larger than the estimated final plume width or to the points of concern.

Parameter Z-Axis Coordinates

Units meters

AT123D Variable

ZDIM(I)

Description Coordinates in the z-direction (vertically perpendicular to flow), where the concentration is desired.

Typical Values The total depth in the z direction is often set to slightly more than the final plume depth or to the points of concern.



8.3.4 AT123D Load Parameters

The AT123D Load Parameters contain information on contaminant load.

Parameter Initial Concentration Units mg/L

AT123D Variable CONC

Description Used to establish an initial concentration within the volume of contaminated groundwater.

Typical Values Site-specific.

Parameter Single Mass Load Units kg/hr

AT123D Variable Q

Description Single contaminant load.

Typical Values Site-specific.

You should not use both the initial concentration and single mass load at the same time.

The single load option is only active if the continuous load option is set to 0.



Parameter Model Time Step

Units Hours

AT123D Variable

DT

Description Time step for the model output.

Typical Values One month (730 hours) when linked to SESOIL.

Parameter Continuous = 0 > Varying

Units Dimensionless

AT123D Variable

NSOURS

Description Specifies the number of individual loads over time.

Typical Values Length of the SESOIL scenario in months. Set to 0 for single load.

Parameter Instantaneous / Continuous Release

Units Dimensionless

AT123D Variable

INSTAN

Description Specifies if the release is instantaneous or continuous.

Typical Values Instantaneous when linked to SESOIL.

Parameter Load Release Rate (Varying Load)

Units kg/time step

AT123D Variable

QSA(I)

Description Varying contaminant mass load for each time step.

Typical Values Site-specific, Used when linked to SESOIL.

The varying load release rate is only active if the continuous load option is greater than 0.



+ , �*-�� !� ��

9.1 Introduction

This section provides a detailed description of the MODFLOW link parameters. The MODFLOW data was designed to be versatile enough to be used with almost any groundwater model.

9.2 MODFLOW Parameters

These parameters are used to establish the link between SESOIL and MODFLOW.

Parameter Time Step

Units months

Description The "Time Step (Months)" data is used to set the length of the time steps to match those in MODFLOW. The number of SESOIL monthly contaminant loads to be combined for each MODFLOW time step. Varying MODFLOW time steps are established by entering varying time step values. For instance entering values of 30, 60, 90 and 120 would produce four MODFLOW time steps. The first would be 30 months long, the second 60 months long, the third would be 90 months long and the forth would be 120 months long. The final time step of 120 months would be used for all subsequent MODFLOW time steps.

Source of Data User defined in MODFLOW.

By default SESOIL produces monthly loads to groundwater. However, MODFLOW is not typically run with such short time steps. The "Time Step (Months)" values are used to establish the number of monthly SESOIL time steps to be combined for each MODFLOW time step. This means that MODFLOW need not be run using a monthly time step when linked to SESOIL.



Parameter Create MODFLOW Data File

Description Checking this box will cause SEVIEW to create a data file which can be imported in to MODFLOW. The file will have the same name as the SESOIL output file but with a .DAT extension.

Example MODFLOW *.DAT File.

1 0.000E+00 0.000E+00 2 1.203E+02 0.000E+00 3 2.490E+02 8.263E-09 4 3.777E+02 1.000E-10 5 2.490E+02 1.000E-10 The first column contains the time step number. The second contains the groundwater recharge during the time step. The final column contains the contaminant concentration over the time step.

Parameter Load MODFLOW Data

Description Checking this box will cause SEVIEW to load MODFLOW data to the clipboard. This data can be pasted in Excel. Clipboard data includes the time step number, length of the time step in days and months, groundwater recharge, mass load to groundwater and the soil leachate concentration.

Example MODFLOW Clipboard Data

Time Step

Number

Length (months)

Length (days)

Start Time

(days)

End Time

(days)

Recharge (cm)

Mass (ug)

Concentration (ppm)

1 0 0 0 0 0.00E+00 0.00E+00 0.00E+00 2 30 912 0 912 1.20E+02 0.00E+00 0.00E+00 3 60 1824 912 2736 2.49E+02 2.06E-01 8.26E-09 4 90 2736 2736 5472 3.78E+02 3.78E-03 1.00E-10 5 120 3648 5472 9120 2.49E+02 2.49E-03 1.00E-10

Parameter Add Initial Time Step

Description Checking this box will cause SEVIEW to add a short time step without any load to the beginning of the MODFLOW data.

MODFLOW data is created whenever you preview or print a SESOIL Pollutant Cycle Report.



). %�/��0��%��SESOIL produces ASCII output file reports which are used by SEVIEW. Each output file includes a summary of all input parameters used in the simulation and the monthly results.

The report files contain a listing of all input parameters, which should be examined to verify the values are correct.

A SESOIL output file can be opened by clicking on the following the SESOIL Output File in the Setup SESOIL & AT123D Runs window. When an output file is opened SEVIEW will display the file in a read only format.

You can also open a SESOIL output file, by selecting the View SESOIL Output File option of the File menu. A window displaying all SESOIL output files in the current working directory will be displayed. If a SESOIL output file is not selected (Cancel is selected, <ESCAPE> is pressed or the window is closed) and no file will be selected and the main menu will be displayed.

SEVIEW includes its own text editor that can be used to examine the contents of any SESOIL (.OUT) or AT123D (.ATO) output file. The basic features of the SEVIEW edit command are similar to other Windows text editors and word processors, except it is much faster when working with the very large output files created by SESOIL and AT123D! See Appendix C for additional information on the SEVIEW text editor.



Although, the SESOIL output file cannot be modified, the file may be saved as a new file. In addition, the output file may be searched using the Find and Find Again commands. Selected data may be copied from the output file using the Windows Copy command.

10.1 The SESOIL Output File

The SESOIL output file contains the model input and results for the hydrologic cycle, washload cycle (if used), and pollutant cycle. The SESOIL report is divided into the heading, input and output sections. An annual summary report is also printed for each year. SESOIL output files can be quite lengthy, for example, a 100-year simulation that includes four layers can produce a 1.0 Mbyte output file. A detailed description of the SESOIL output file is presented below.

10.1.1 SESOIL Heading

The heading portion of the SESOIL output file contains a description of the version of SESOIL being used. It also contains notes regarding the modifications to the program and who made them.

10.1.2 SESOIL Input

The input section is presented below the heading, it contains a summary of the input file descriptions followed by a list of the input parameters used by the model. The input parameters are subdivided into tables containing soil, chemical, washload (if used), and application data. The table (labeled “YEAR - 1 MONTHLY INPUT PARAMETERS”) reports the monthly climatic data, the contaminant input parameters for each month, and the monthly washload factors (if used) for the first year. A description of the input parameters is presented in Section 6. Additional input information concerning SESOIL input parameters is presented in Appendix A “Introduction And Overview of the SESOIL Model”. Following the data for the first year, the monthly input parameters for the climate, contaminant, and washload are given for each year. If the data for any of these categories (i.e., climatic, pollutant, or washload) are the same as the previous year, they will not be printed, instead a message is presented stating, for example, “CLIMATIC INPUT PARAMETERS ARE SAME AS LAST YEAR.”. This is common when long-term monthly averaged data are used.

The output file should be checked carefully to verify that the input parameters are correct and to review any warning or error messages that may have been generated.

SESOIL can identify some obvious errors in the input data and insert the error or warning messages into the output file. The messages will be printed immediately preceding the section entitled “GENERAL INPUT PARAMETERS”. For example, the fraction of cloud cover must be between 0.0 and 1.0 and an error message is printed if it is not. Warnings or errors associated with the hydrologic cycle will be printed following the input data. A list of all SESOIL error and warning messages including a description is presented in Appendix A.



10.1.3 SESOIL Output

The next section of the output file contains the model results, which are divided into annual subsections. These data tables are grouped by the year simulated, with the results reported for each month. The monthly results are organized in the following sequence:

• Hydrologic cycle components

• Washload cycle components (if used)

• Contaminant mass input

• Contaminant concentration distribution for each layer or sub-layer

• Contaminant depth The monthly output results are followed by an annual summary. The following sections discuss each portion of the output file in detail.

10.1.3.1 Hydrologic Cycle

Reports for each year begin with the monthly results for the hydrologic cycle. The first parameter printed, labeled “MOIS. IN L1 (%)”, is the volumetric soil moisture content in the root zone, defined in SESOIL as the first 100 cm of the unsaturated soil zone. The next parameter, labeled “MOIS. BELOW L1 (%)”, is the average volumetric soil moisture content for the entire soil column (from the surface to the groundwater table). For most applications the values for these parameters will be identical for each month. The hydrologic cycle of SESOIL needs further refinement to produce any significant difference between these two parameters since an average permeability is used for the entire soil column in the hydrologic cycle. At present, only very dry climatic conditions are likely to produce a difference in the values. The calculated precipitation “PRECIPITATION (CM)” in centimeters per month is presented next. The precipitation data is followed the by monthly infiltration, evapotranspiration, soil moisture retention, surface water runoff, and groundwater runoff (recharge) parameters, in centimeters per month.

The results for the first year of the hydrologic cycle are slightly different than all subsequent years, as SESOIL iterates on soil moisture content until the calculated precipitation is within one percent of the precipitation entered. See Section A2.3 for additional information on the hydrologic cycle.

Infiltration into the soil column is established as the difference between the precipitation and the surface runoff. The infiltration rate is equal to the moisture retention plus the evapotranspiration plus the groundwater runoff (see Section 11.2.1). The yield is simply the surface runoff plus the groundwater runoff (recharge). The next two lines, “PAU/MPA (GZU)” and “PA/MPA (GZ)”, are the calculated precipitation for each month for the root



zone and the entire soil column, respectively, divided by the measured precipitation. (See Appendix A, Section A2.3 for more information concerning the hydrologic cycle components.) A list of all SESOIL hydrological output parameters is presented in Table 11.

Table 11 SESOIL Hydrological Output Parameters

Hydrological Parameters Process Definition EVAPOT. (CM/DAY) Daily calculated evapotranspiration in cm. EVAPOTRANS. (CM) Monthly calculated evapotranspiration in cm. GRW. RUNOFF (CM) Monthly calculated groundwater runoff (groundwater

recharge) in cm. MOIS. BELOW L1 (%) The average volumetric soil moisture content of the

entire soil column (from ground surface to the groundwater table).

MOIS. IN L1 (%) The volumetric soil moisture content of the root zone (the upper 100 cm of the soil column).

MOIS. RETEN (CM) Calculated monthly soil moisture retention (cm). NET INFILT. (CM) Calculated monthly infiltration (precipitation entering

the top of the soil column in cm). PA/MPA (GZ) The calculated monthly precipitation of the entire soil

column (from ground surface to the groundwater table) divided by the measured precipitation.

PAU/MPA (GZU) The calculated monthly precipitation of the root zone (the upper 100 cm of the soil column) divided by the measured precipitation.

PRECIP. (CM) User specified input precipitation data in cm. PRECIPATION (CM) Calculated precipitation in cm. SESOIL does not directly

utilize the user supplied precipitation data. It iterates on soil moisture until the calculated precipitation is within one percent of the measured input data (See Appendix A Section A2.3 for more information).

SUR. RUNOFF (CM) Calculated monthly surface water runoff in cm. YIELD (CM) Monthly sum of surface runoff plus the groundwater

runoff (recharge).

10.1.3.2 Washload Cycle

If used the monthly washload cycle information is presented following the hydrologic cycle results. The sediment yield is given on the first two lines in kg/km2 and g/cm2, respectively (labeled as “WASHLD (KG/SQ KM)” and “(G/SQ CM)”). The next line, labeled “ENRICHMT RATIO (-)”, is defined as the ratio of the total specific surface area for the sediment and organic matter to that of the original soil (Knisel et. al., 1983). The index of specific surface in m2/g of total sediment and is labeled “SURF. IDX (M**2/G)” (see Knisel et. al., 1983). Next, the relative amounts of clay, silt, and sand in the eroded topsoil particles are given, labeled as “SED. FRAC CLAY”, “SED.



FRAC SILT”, and “SED. FRAC SAND”. These three numbers should add to 1.0 for each month. The last line of the washload results labeled “SED. FRAC OC”, is the fraction of organic matter in the eroded sediment. Refer to Appendix A, Section A2.4 for a detailed description of the washload cycle. A description of all SESOIL washload output parameters is presented on Table 12.

Table 12 Sediment Washload Output File Parameters

Washload Parameters Process Definition WASHLD (KG/SQ KM) Sediment yield in kg/km2. (G/SQ CM) Sediment yield in g/cm2. ENRICHMT RATIO (-) The ratio of the total specific surface area for the sediment

and organic matter to that of the original soil. SURF. IDX (M**2/G The index of specific surface in m2/g of the total sediment. SED. FRAC CLAY Relative amount of clay in the eroded particles. SED. FRAC SILT Relative amount silt in the eroded particles. SED. FRAC SAND Relative amount of sand in the eroded particles. SED. FRAC OC The fraction of organic matter in the eroded sediment.

10.1.3.3 Contaminant Mass Load

The monthly contaminant mass load, in units of µg, is the next table in the output file. These values include the amount of chemical load in precipitation (labeled “PRECIP.”) and the load in each of the layers (or sub-layers) specified in the simulation, labeled “LOAD UPPER”, “LOAD ZONE 2”, “LOAD ZONE 3”, and “LOAD LOWER” in µg. PRECIP is computed by multiplying the contaminant load in precipitation (ASL), by the water solubility (SL), by the infiltration rate computed by the hydrologic cycle (NET. INFILT.), and the area of the application (AR from the application file). Values displayed in the load for each layer are simply the area of application (AR) multiplied by the contaminant application (POLIN for each layer defined in the application file). Note that if there are sub-layers within a major layer, then the load for the major layer is added to the first sub-layer of that layer, not evenly for each of the sub-layers. If an instantaneous load was specified (see the line labeled “SPILL (1) OR STEADY APPLICATION (0):” under “-- APPLICATION INPUT PARAMETERS -”) the input listed for the month for the surface layer is loaded into the layer in the first time step of the month. If steady loading was specified, the input for the month is spread out evenly during each time step of the month. Note that spill loading applies only to the first layer. (Refer to Appendix A, Sections A2.5.2 and Section 6.7 for more details.) The total input to the soil column is given next (labeled “TOTAL INPUT”) and is simply the sum of all mass loads for a given month.



10.1.3.4 Contaminant Mass

The next table in the output file displays the distribution of contaminant mass in µg for each process for each sub-layer of the soil column and for each month of the year. Table 13 lists of all of the SESOIL mass components in the order in which they are displayed in the output file. The contaminant mass is printed for each layer and sub-layer from the surface to the bottom of the soil column.

If a monthly SESOIL output process in a particular layer or sub-layer is zero for each month of the year, it will not be printed in the output file to conserve disk space.

If there is more than one sub-layer in the first layer (upper soil zone), then the output for the second sub-layer follows and the order of the parameters and their definitions are the same as given in Table 13. However, the first three components listed in Table 13 (i.e., “SUR. RUNOFF”, “IN WASHLOAD”, and “VOLATILIZED”) apply only to the uppermost sub-layer of the first layer (upper soil zone). The fourth component listed in Table 13 (i.e., “DIFFUSED UP”) applies to all layers and sub-layers except the uppermost sub-layer of the first layer (upper soil zone). Likewise, this table continues for each layer (and sub-layer) down through the soil column.

If all results for all components of a layer or sub-layer are zero for the year, then the only label printed is the number of the sub-layer. When the contaminant reaches the bottom of the soil column (the lowest sub-layer of the “LOWER SOIL ZONE”), the last component printed in the mass distribution table is the mass of contaminant that leaves the unsaturated zone and enters the groundwater in µg (labeled “GWR. RUNOFF”).

Table 13 Contaminant Mass (�g) Processes in the Output File

Process Label Process Definition SUR. RUNOFF Mass lost via surface runoff (upper most sub-layer only). IN WASHLD Mass lost via soil erosion (upper most sub-layer only).

VOLATILIZED Mass volatilized to air (upper most sub-layer only). DIFFUSED UP Mass diffused upward from the layer (sub-layer) to the layer

(sub-layer) above it. DEGRAD MOIS Mass degraded in the soil moisture phase. DEGRAD SOIL Mass degraded in the soil adsorbed phase. HYDROL MOIS Mass degraded due to hydrolysis in the soil moisture phase. HYDROL SOIL Mass degraded due to hydrolysis in the adsorbed soil phase. HYDROL CEC Mass degraded due to hydrolysis of the mass of the contaminant

immobilized by cation exchange. OTHER SINKS Mass removed by a user defined process. OTHER TRANS Mass transformed by a user defined process.

IN SOIL MOI Mass in the soil moisture phase. ADS ON SOIL Mass adsorbed on the soil. IN SOIL AIR Mass in the soil air phase. PURE PHASE Mass in pure phase. COMPLEXED Mass that is complexed.

IMMOBIL CEC Mass immobilized by cation exchange. GWR. RUNOFF Mass that leaves the unsaturated zone and enters the

groundwater (lower most sub-layer only). TOTAL INPUT Total contaminant mass load (monthly sum of all input loads)



Following the contaminant mass distribution results is a table of the monthly contaminant concentrations for each chemical phase for each sub-layer in µg/ml. Table 14 presents a list of all chemical phases. If all concentrations for a particular phase are zero for each month of the entire year, the results are not printed. The pure phase concentration will be zero unless the simulated contaminant concentration in the soil moisture exceeds the solubility of the chemical. When this happens, the model sets the soil moisture concentration to the solubility (the %SOLUBILITY defined in Table 14 will be 100.0), and the excess chemical is assumed to be in the pure phase.

Transport of the chemical in the pure phase is not simulated; the pure phase is treated as an immobile storage term and the mass of the chemical in this phase is used as input to the same layer in the next time step.

Table 14 Contaminant Concentration in the Output File

Concentration

Label Process Definition

MOISTURE Contaminant concentration in the soil moisture phase in µg/ml (ppm). ADSORBED Contaminant concentration in the soil adsorbed phase in µg/g (ppm).

SOIL AIR Contaminant concentration in the soil air phase in µg/ml (ppm). FREE LIGAND Free ligand concentration in µg/ml (ppm). PURE PHASE Contaminant concentration in the pure phase in µg/ml (ppm).

%SOLUBILITY Not a concentration, it is the predicted soil moisture contaminant concentration divided by the solubility for the chemical, multiplied by 100 to give percent.

10.1.3.5 Contaminant Depth

Contaminant depth in cm is presented next (labeled “POL DEP CM”). This depth is calculated from Equation A11 in Appendix A, Section A2.5.2 and is simply the depth of the leading edge of the contaminant. Once the contaminant reaches groundwater, the depth will always be equal to the depth to the groundwater table.

10.1.4 Output of Annual Summary

SESOIL prints an annual summary report following the table of the concentration data. Parameters in this report are the same as listed above for monthly results, but either a “TOTAL” or an “AVERAGE” is given for each parameter. “TOTAL” is simply the sum of values given for the 12 months for the parameter listed and “AVERAGE” is the sum for the year divided by 12. The annual summary is organized in the following order:

• Total contaminant mass inputs • Hydrologic cycle components (average or total) • Total contaminant mass removed from each layer or sub-layer • Average contaminant concentration distributions for each layer or sub-layer • Maximum contaminant depth



The final end-of-the-year contaminant mass in the soil moisture, adsorbed on soil, in soil air, immobilized by cation exchange, complexed, and in the pure phase would be found under the last month of the year (September) in the monthly mass distribution (Table 11).

The final portion of the annual report, contains the maximum depth below ground surface that the contaminant has migrated to in meters is given (labeled “MAX. POLL. DEPTH (M)”). This depth will always be the same as the last month of the year (September) presented above in the SESOIL output file (see line labeled “POL DEP CM”).



)) �*� ��%��SEVIEW includes powerful tools designed to document modeling activities. These tools include automated results to produce pollutant and hydrologic cycle report. In addition to the automated data reduction, SEVIEW provides access to all SESOIL parameters. This means that examination of SESOIL results is not limited to predetermined report parameters. In addition results from numerous SESOIL scenarios can be combined in a single table or graph. Using SEVIEW with your spreadsheet and/or word processing software allows you to present model results that meet your specific requirements. SEVIEW provides you with almost unlimited flexibility in evaluating SESOIL data contained in the SESOIL output file. As individual projects requirements vary you can use SEVIEW to extract data and create a wide combination of data plots. In addition, since you are using your spreadsheet and word processor there are no new commands to learn. An overview how SEVIEW works with the SESOIL output is provided below.

SESOIL output files can be very large containing over 815 monthly input and output data sets. A single SESOIL output file can contain up to about 10,000,000 monthly values for a 999 year run!

11.1 Mass Balance Report

SEVIEW is the only SESOIL post-processor that includes a mass balance report. The mass balance report is generated as part of the Pollutant Cycle Report. SEVIEW will calculate the mass balance distribution for the final month of the SESOIL output file. The mass balance report displays the mass in each SESOIL process even if the process was not used. Total input is the sum of the contaminant mass for all SESOIL processes for all months and is not the same as the “TOTAL INPUT” data set. The “TOTAL INPUT” data set contains the monthly contaminant load, while the mass balance report total load is the sum of all loads.

The mass balance report was used to identify a significant mass balance error which is corrected in the version of SESOIL provided with SEVIEW.

Although SEVIEW can produce a mass balance report within several seconds, creating the report is not simple. For example: Mass within a SESOIL output file with 10 sub-layers per layer can be distributed in up to 6,761,232 individual values for a 999 year run.



11.2 SESOIL Data Sets

SESOIL data sets include all monthly input parameters and output results. SESOIL data sets include for example the monthly load, precipitation and contaminant load to groundwater. A single SESOIL output file can have containing over 815 monthly input and output data sets (with up to 564 data sets for mass distribution alone). This section provides several examples from the Pollutant and Hydrologic Cycle reports and how SEVIEW along with a spreadsheet program can be used to extract and evaluate the results of a SESOIL model scenario.

11.2.1 SESOIL Hydrologic Cycle Reports

Precipitation within SESOIL hydrologic cycle is divided into two separate components. The first component is composed of monthly surface water runoff and net monthly infiltration data. The sum of these two data sets is equal to the monthly precipitation. The second component is composed of evapotranspiration, soil moisture retention and groundwater recharge which are equal to the net monthly infiltration. Reviewing SESOIL water balance information can be used to calibrate the model to known site conditions (see Appendix A, Section A2.3.3).

11.2.1.1 Precipitation

Precipitation is distributed between surface water runoff and net infiltration. Surface water runoff is calculated based on the duration and distribution of rain fall event intensity and soil permeability (see Appendix A, Section A2.3). The difference between surface water runoff and precipitation enters the top of the SESOIL column as net infiltration. SEVIEW extracts the “SUR. RUNOFF (CM)” and “NET INFILT. (CM)” data sets which are plotted and tabulated in the Hydrologic Cycle Report. A graphical presentation of the monthly surface water runoff and infiltration is presented at the top of the report. The table at the bottom of the report contains the “SUR. RUNOFF (CM)”, and “NET INFILT. (CM)” data sets.

Hydrologic water balance parameters are based on year 2 results, as the values are slightly different for the first year. See Appendix A, Section A2.3 Equations A1 and A2 for additional information.

11.2.1.2 SESOIL Water Balance

Precipitation that has infiltrated into the soil column can evaporate to the atmosphere, remain bound as soil moisture or recharge groundwater. This means that the sum of the “EVAPOTRANS. (CM)”, “MOIS. RETEN (CM)” and “GRW. RUNOFF (CM) data sets equals the “NET INFILT. (CM) for each month. SEVIEW extracts the “EVAPOTRANS. (CM)”, “MOIS. RETEN (CM)” and “GRW. RUNOFF (CM)” data to plot and tabulate the results. The graphical presentation of the monthly water balance is presented in the Hydrologic Cycle Report. The table at the bottom of the Hydrologic



Cycle Report contains the “EVAPOTRANS. (CM)”, “MOIS. RETEN (CM)” and “GRW. RUNOFF (CM)” data sets.

The monthly “GRW. RUNOFF (CM)” is used along with the monthly mass entering groundwater and the area of the soil column to establish the SESOIL leachate concentration.

11.2.2 Additional SESOIL Results

In addition to the automated Pollutant Cycle and Hydrologic Cycle reports, SEVIEW can be used to extract any data set. The following sections contain some examples of what is possible.

11.2.2.1 Soil Moisture

The percent of soil moisture content and precipitation can be used to calibrate SESOIL to known site conditions. The average volumetric soil moisture content percent for the soil column is contained in the “MOIS. BELOW L1 (%)” data set. The “MOIS. IN L1 (%)” data set contains the volumetric soil moisture content in the root zone (upper 100 cm of the soil column), see Section 10.1.3. SEVIEW and your spreadsheet can be used to plot or tabulate the soil moisture percentages. A plot of the “MOIS. BELOW L1 (%)” and “MOIS. IN L1 (%)” data set is presented below. The results are also presented on Table 15.



Table 15 Monthly Soil Moisture Content

Month Soil Type

Sand % Silt % Clay % October 4.976 10.347 13.078 November 5.526 10.407 13.098 December 6.126 10.527 13.118 January 6.201 10.722 13.138 February 5.651 10.617 13.158 March 5.601 10.647 13.178 April 5.501 10.767 13.178 May 4.926 10.752 13.218 June 5.101 10.707 12.978 July 5.076 10.572 12.618 August 4.901 10.512 12.358 September 4.976 10.377 12.518 Average % 5.38 10.58 12.97

11.2.2.2 Contaminant Concentrations

Depending on the number of sub-layers used, SESOIL can produce up to 200 monthly concentration data sets per output file. You can use SEVIEW to select any of the concentration data sets for evaluation. For example: you may wish to assess contaminant concentrations adsorbed on soil to evaluate potential threats to human health from direct contact through time. A plot of adsorbed on soil concentrations is presented below.



11.2.3 Contaminant Depth

The SESOIL output file includes the “POL DEP CM” data set which contains the monthly depth below ground surface of the leading edge of the contaminant. SEVIEW extracts this data and plots the results in the Pollutant Cycle Report.

Once the leading edge of the contaminant reaches the water table, the depth of the contaminant will equal the depth of the water table.

SEVIEW estimates a travel time to the water table for model scenarios in which the contaminant did not reach groundwater. The estimate is based on the rate of contaminant mobility.

11.2.4 Summing SESOIL Data

Mass within a SESOIL output file can be distributed in up to 564 monthly data sets. SEVIEW can be used to sum multiple data sets creating new SESOIL data sets. The summation of SESOIL data is one of the most powerful commands within SEVIEW; as individual SESOIL data sets may be summed to create additional data sets. For example, you could sum the data sets for the mass volatilized, in soil air, adsorbed on soil, contained in soil moisture and in groundwater runoff for all layers and sub-layers within the SESOIL output file. Or you could restrict the summation to the mass in soil moisture contained all sub-layers of a layer.

If the number of sub-layers is set to 10 in each of the four layers, a single 999 year SESOIL output file could contain 6,761,232 monthly mass values.



)� %�/��0��(�)� *�%�� The AT123D model produces ASCII output files which are used by SEVIEW. Each output file contains a summary of all model input parameters and the results of the model scenario.

SEVIEW includes its own text editor that can be used to examine the contents of any SESOIL (.OUT) or AT123D (.ATO) output file. The basic features of the SEVIEW edit command are similar to other Windows text editors and word processors, except it is much faster when working with the very large output files created by SESOIL! See Appendix C for additional information on the SEVIEW text editor.

Although, the AT123D output file cannot be modified, the file may be saved as a new file. In addition, the output file may be searched using the Find and Find Again commands. Selected data may be copied from the output file using the Windows Copy command.

12.1 The AT123D Output File

The AT123D output file contains input parameters and output results for the model scenario. The AT123D output file is divided into the heading, input and output sections. A detailed description of the AT123D output file is presented below.

12.1.1 AT123D Heading

The heading portion at the top of the output file contains a description of the version of AT123D used. It also contains a description of modifications to the code and who made them.

12.1.2 AT123D Input Parameters

The first portion of the output file contains a summary of the input parameters used by the model. A description of the AT123D input parameters used by SEVIEW is presented in Section 8. A complete description of all AT123D input parameters is presented in Appendix B “AT123D Data Input Guide”.

The user should check this section of the output file carefully and verify that the input data is correct and to review any warning or error messages that may have been generated.



The AT123D output file contains a report of all input parameters. The following is an example of an AT123D input parameter report. Benzene in Sand NO. OF POINTS IN X-DIRECTION ...................... 7 NO. OF POINTS IN Y-DIRECTION ...................... 5 NO. OF POINTS IN Z-DIRECTION ...................... 2 NO. OF ROOTS & NO. OF SERIES TERMS ................ 500 NO. OF BEGINNING TIME STEPS ....................... 25 NO. OF ENDING TIME STEP ........................... 241 NO. OF TIME INTERVALS FOR PRINTED OUT SOLUTION .... 1 INSTANTANEOUS SOURCE CONTROL = 0 FOR INSTANT SOURCE 1 SOURCE CONDITION CONTROL = 0 FOR STEADY SOURCE .... 240 INTERMITTENT OUTPUT CONTROL = 0 NO SUCH OUTPUT .... 1 CASE CONTROL =1 THERMAL, = 2 FOR CHEMICAL, = 3 RAD 2 SOIL ORGANIC CARBON CONTENT (OC) .................. 0.50000 ORGANIC CARBON ADSORPTION COEFFICIENT (KOC) ....... 0.3100E+02 INITIAL CONTAMINANT LOAD (MG/KG) .................. 0.0000E+00 INITIAL CONTAMINANT LOAD (KG) ..................... 0.7300E+03 AQUIFER DEPTH, = 0.0 FOR INFINITE DEEP (METERS) ... 0.00000 AQUIFER WIDTH, = 0.0 FOR INFINITE WIDE (METERS) ... 0.00000 BEGIN POINT OF X-SOURCE LOCATION (METERS) ......... -1.58100 END POINT OF X-SOURCE LOCATION (METERS) ........... 1.58100 BEGIN POINT OF Y-SOURCE LOCATION (METERS) ......... -1.58100 END POINT OF Y-SOURCE LOCATION (METERS) ........... 1.58100 BEGIN POINT OF Z-SOURCE LOCATION (METERS) ......... 0.00000 END POINT OF Z-SOURCE LOCATION (METERS) ........... 0.00000 POROSITY .......................................... 0.25000 HYDRAULIC CONDUCTIVITY (METER/HOUR) ............... 0.03600 HYDRAULIC GRADIENT ................................ 0.00300 LONGITUDINAL DISPERSIVITY (METER) ................. 2.16000 LATERAL DISPERSIVITY (METER) ...................... 0.20000 VERTICAL DISPERSIVITY (METER) ..................... 0.02000 DISTRIBUTION COEFFICIENT, KD (M**3/KG) ............ 0.00016 SOURCE CONCENTRATION (mg/L) ....................... 0.00000 MOLECULAR DIFFUSION MULTIPLY BY TORTUOSITY(M**2/HR) 0.3528E-05 DECAY CONSTANT (PER HOUR) ......................... 0.0000E+00 BULK DENSITY OF THE SOIL (KG/M**3) ................ 0.1700E+04 DENSITY OF WATER (KG/M**3) ........................ 0.1000E+04 ACCURACY TOLERANCE FOR REACHING STEADY STATE ...... 0.1000E-01 TIME INTERVAL SIZE FOR THE DESIRED SOLUTION (HR) .. 0.7300E+03 DISCHARGE TIME (HR) ............................... 0.1752E+06 WASTE RELEASE RATE (KCAL/HR), (KG/HR), OR (CI/HR) . 0.7300E+03

The next section of the AT123D output file contains the coordinates (in meters) where contaminant concentrations were determined. The number of points for each direction are dependent on values entered for x, y and z axis displayed above. X COORDINATES ... .00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 Y COORDINATES ...



20.00 10.00 .00 -10.00 -20.00 Z COORDINATES ... .00 5.00 10.00

The next portion of the output report contains a list of transient source release rates in kilograms per month. The number of transient source release rates is dependent on the length of the SESOIL model scenario.

The transient source release data is the monthly contaminant load from the soil column as determined by SESOIL.

LIST OF TRANSIENT SOURCE RELEASE RATE .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .2011E-03 .6709E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .1362E-02 .1639E-02 .1394E-02 .9408E-03 .6251E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .1272E-02 .1533E-02 .1304E-02 .8794E-03 .5842E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .1187E-02 .1428E-02 .1214E-02 .8180E-03 .5431E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .1102E-02 .1324E-02 .1125E-02 .7576E-03 .5029E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .1020E-02 .1224E-02 .1039E-02 .6995E-03 .4642E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .9404E-03 .1128E-02 .9569E-03 .6442E-03 .4275E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .8655E-03 .1038E-02 .8798E-03 .5922E-03 .3930E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .7952E-03 .9531E-03 .8078E-03 .5437E-03 .3607E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .7296E-03 .8743E-03 .7408E-03 .4985E-03 .3307E-03 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00



12.1.3 AT123D Results

The next section of the AT123D output file presents the model results. This section is divided into the initial results and predicted contaminant groundwater concentrations.

12.1.3.1 Initial Results

The initial model results include the retardation factor, retarded Darcy velocity, retarded longitudinal dispersion coefficient, retarded lateral dispersion coefficient and retarded vertical dispersion coefficient. A portion of the AT123D output is presented below. RETARDATION FACTOR ................................ .3822E+01 RETARDED DARCY VELOCITY (M/HR) .................... .3768E-06 RETARDED LONGITUDINAL DISPERSION COEF. (M**2/HR) .. .2901E-01 RETARDED LATERAL DISPERSION COEFFICIENT (M**2/HR) . .2901E-01 RETARDED VERTICAL DISPERSION COEFFICIENT (M**2/HR) .2901E-01

12.1.3.1.1 Retardation Factor The retardation factor is the unitless ratio of the groundwater seepage velocity to the rate of organic contaminant migration. The retardation factor is used to estimate the slower rate of contaminant migration due to sorption to the solid aquifer matrix. The retardation factor is determined based on aquifer and contaminant properties using the following expression:

RK

ndb d

e

= +1ρ

Where: Parameter Description

Kd Distribution coefficient ne Effective porosity ρb Bulk density of the soil Rd Retardation factor

12.1.3.1.2 Retarded Darcy Velocity The retarded Darcy velocity in meters/hour is determined using the following equation.

�U

Kn R

h

e d

= ∇


∇ Hydraulic gradient (Del operator with respect to x, y, and z) Kh Hydraulic conductivity ne Effective porosity Rd Retardation factor �

U The retarded Darcy velocity vector



12.1.3.1.3 Retarded Dispersion Coefficients The next three lines of the output file contain the retarded longitudinal, lateral and vertical dispersion coefficient in meters2/hour. The retarded dispersion coefficients are calculated using the following equations.

K UD

n Rxx Le d

= +α

K UD

n Ryy Te d

= +α

K UD

n Rzz Ve d

= +α

Where:

Parameter Description αL Longitudinal dispersivity αT Transverse dispersivity αV Vertical dispersivity D Molecular diffusion coefficient multiply by tortuosity

Kxx Longitudinal component of the retarded dispersion tensor (x-axis) Kyy Transverse component of the retarded dispersion tensor (y-axis) Kzz Vertical component of the retarded dispersion tensor (z-axis) ne Effective porosity Rd Retardation factor U The magnitude of the retarded seepage velocity vector (

�U )

12.1.4 Contaminant Concentration Results

The next section of the output file displays the distribution of contaminant mass in ppm for each time step and coordinate simulated. The results of the AT123D program are presented as concentration data tables grouped by time steps in days. A portion of an AT123D output file is presented below: DISTRIBUTION OF CHEMICALS IN PPM AT 3650.00 DAY Z = .00 X Y .00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 20.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 10.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 -10.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 -20.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 Z = 5.00 X Y .00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 20.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00



10.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 -10.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 -20.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 Z = 10.00 X Y .00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 20.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 10.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 -10.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 -20.00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00 .000E+00



) ��1��2��

13.1 Solutions to Common Problems

This section provides solutions to common problems users have encountered using SEVIEW.

Problem: Numerous corrupt files and/or lost data.

Solution: SESOIL, AT123D and SEVIEW make extensive use of the hard drive. Make sure that your hard drive is operating correctly by running the scandisk utility. The scandisk program examines a drive for errors and corrects any problems it encounters.

Problem: SESOIL does not run correctly and the SESOIL window closes before you

can read the error message. Solutions: Re-select the Setup SESOIL & AT123D Runs command (see Section

5.2.4.1) and determine if the scenario has been run by clicking on the following the SESOIL output file.

1. If the SESOIL output file is displayed examine it for any error or

warning messages. Next verify that all input parameters are correct. If you find an error close the output file and use the COPY command in the journal and correct the SESOIL input data set. Now select to run the SESOIL scenario and close the Setup SESOIL & AT123D Runs window and RUN SESOIL.

2. If the output file is not displayed close the Setup SESOIL &

AT123D Runs window and select the Go To DOS command. At the DOS prompt enter SERUN and press <Enter>. SESOIL will now attempt to run, SESOIL, however the DOS will not close allowing you to read any error messages.

Problem: SEVIEW displays the following set of error messages when you copy the

SESOIL data to BIOSCREEN.



Solution: Start Microsoft EXCEL and/or open the BIOSCRN4.XLS spreadsheet file.



)� �%�!�� Anderson, M. P. and Woessner, 1992. Applied Groundwater Modeling, Academic Press, San Diego, CA. Bear, J., S. B. Milovan, and R. R. Randall, Fundamentals of Ground-Water Modeling, U. S. Environmental Protection Agency, Office of Research and Development and the Office of Solid Waste and Emergency Response, 1992, 11p. EPA/540/S-92-005. Bonazountas, M., and J. Wagner (Draft), SESOIL: A Seasonal Soil Compartment Model. Arthur D. Little, Inc., Cambridge, Massachusetts, prepared for the US. Environmental Protection Agency, Office of Toxic Substances, 1981, 1984. (Available through National Technical Information Service, publication PB86-112406). Bonazountas, M., D. H. Hetrick, P. T. Kostecki and E. J. Calabrese, SESOIL in Environmental Fate and Risk Modeling, 1997, Amherst Scientific Publishers, 661p. Ladwig, K. J. and Hensel, B. R., Groundwater Contamination Susceptibility Evaluation, SESOIL Modeling, Prepared for Wisconsin Department of Natural Resources, Madison, WI, 1993. Newell, C. J., McLeod R. K., Gonzales J. R., and Wilson J. T., BIOSCREEN Natural Attenuation Decision Support System, User’s Manual, Version 1.3, U.S. E.P.A. Cincinnati Ohio, 63pp, 1996. Odencrantz, J. E., J. M, Farr, and C, E. Robinson, Levine/Fricke, Inc., A Better Approach to Soil Cleanup Levels Determination. In: Transport Model Parameter Sensitivity for Soil Cleanup Level Determinations Using SESOIL and AT123D in the Context of the California Leaking Underground Fuel Tank Field Manual, Sixth Annual Conference on Hydrocarbon Contaminated Soils: Analysis, Fate, Environmental and Public Health, in Regulations, University of Massachusetts at Amherst, September, 1991. Odencrantz, J, E., J. M, Farr, and C, E. Robinson, Transport Model Parameter Sensitivity for Soil Cleanup Level Determinations Using SESOIL and AT123D in the Context of the California Leaking Underground Fuel Tank Field Manual. Journal of Soil Contamination , 1 (2), 159-182, 1992. Schneiker, R. A., SEVIEW SESOIL Data Management, User’s Guide, Version 2.5, Environmental Software Consultants, Inc., Milwaukee, Wisconsin, 1996. Schneiker, R. A., SEVIEW SESOIL-BIOSCREEN Link, User’s Guide, Version 2.6, Environmental Software Consultants, Inc., Milwaukee, Wisconsin, 1996. Schneiker, R. A., SEVIEW Integrated Contaminant Transport and Fate Modeling System, User’s Guide, Version 5.0, Environmental Software Consultants, Inc., Milwaukee, Wisconsin, 2000.



Schneiker, R. A., SEVIEW Integrated Contaminant Transport and Fate Modeling System, User’s Guide, Version 6, Environmental Software Consultants, Inc., Milwaukee, Wisconsin, 2003. USEPA, Assessment Framework For Ground-Water Model Applications, Office of Solid Waste and Emergency Response Directive No. 9029.00, EPA 500-B-94-003, July, 1994. Yeh, G. T., AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste Transport in the Aquifer System. ORNL-5602, Oak Ridge National Laboratory, Oak Ridge, TN 37831, 1981 (Available through National Technical Information Service, Publication ORNL-5602/LT). Yeh, G. T., H. Trussel and J. Hoopes “AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste Transport in the Aquifer System,” Wisconsin Department of Natural Resources, 1987.



Appendix A

Introduction and Overview of the SESOIL Model

Portions of this Appendix were originally presented as part of

“The New SESOIL User’s Guide” prepared for the

Wisconsin Department of Natural Resources



()3.�� SESOIL is an acronym for Seasonal Soil compartment model and is a one-dimensional vertical transport model for the unsaturated soil zone. It is an integrated screening-level soil compartment model designed to simultaneously model water transport, sediment transport, and contaminant fate. It was developed for EPA’s Office of Water and the Office of Toxic Substances (OTS) in 1981 by Arthur D. Little, Inc. SESOIL was updated in 1984 to include a fourth soil compartment (the original model included up to three layers) and the soil erosion algorithms (Bonazountas and Wagner, 1984). SESOIL is based on mass balance and partitioning of the contaminant between the dissolved, sorbed, vapor, and pure phases. A comprehensive evaluation of SESOIL performed by Watson and Brown (1985) uncovered numerous deficiencies in the model, and subsequently, SESOIL was modified extensively by Hetrick et al., at Oak Ridge National Laboratory (ORNL) to enhance its capabilities (see Hetrick et al., 1986, 1988, 1989). The version of SESOIL included with SEVIEW was modified in 1997 by M. J. Barden then of the Wisconsin Department of Natural Resources to correct a mass balance error and by R. A. Schneiker to run to 999 years. SESOIL is a public model and is written in FORTRAN.

The version of SESOIL included with SEVIEW includes an improved mass balance routine.

SESOIL was developed as a screening-level model, utilizing less soil, chemical, and climatological data than most other similar models. Output from the SESOIL model includes time-varying contaminant concentrations at various soil depths and contaminant loss from the unsaturated zone in terms of surface runoff, leaching to groundwater, volatilization, and biodegradation. The SESOIL model accepts time-varying contaminant loading. For example, it is able to simulate chemical releases to soil from a variety of sources such as landfill disposal, spills, agricultural applications, leaking underground storage tanks, or deposition from the atmosphere. Other potential applications of SESOIL include long term leaching studies from waste disposal sites, pesticide and sediment transport on watersheds, studies of hydrologic cycles and water balances of soil compartments, and pre-calibration runs for other simulation models. One may also run the model to estimate the effect of various site management or design strategies on contaminant distribution in the environment. SESOIL can be used as a screening tool in performing exposure assessments. OTS used the model to predict the behavior of contaminants in soil compartments for analyzing and prioritizing chemical exposures. A number of studies have been conducted on the SESOIL model including sensitivity analysis, comparison with other models, and comparisons with field data (Bonazountas et al., 1982; Wagner et al., 1983; Hetrick, 1984; Kincaid et al., 1984; Watson and Brown, 1985; Hetrick et al., 1986; Melancon et al., 1986; Hetrick et al., 1988; Hetrick et al., 1989). SESOIL has been applied to: risk assessments concerning direct coal liquefaction (Walsh et al., 1984), incineration of hazardous waste (Holton et al., 1985; Travis et al., 1986), transport of benzene to groundwater (Tucker et al., 1986), soil cleanup levels in California (Odencrantz et al., 1991, 1992), and site sensitivity ranking for Wisconsin soils for the Wisconsin Department of Natural Resources (Ladwig et al., 1993)



The soil compartment in SESOIL extends from the surface through the unsaturated zone to the groundwater table. Typically, SESOIL is used to estimate the rate of migration of chemicals through soil and the concentration of the chemicals in soil layers following chemical release to the soil environment. SESOIL simulation of chemical persistence considers mobility, volatility, and degradation. The model performs calculations on an annual or monthly basis, and can simulate up to 999 years of chemical transport. The model requires several types of chemical- and site-specific data to estimate the concentration of the chemical in the soil, its rate of leaching toward groundwater, and the impact of other environmental pathways. The user is required to provide chemical properties and release rates, and soil and climate data. This Appendix along with the SEVIEW User’s Guide are designed to provide users of SESOIL with the information needed to efficiently and appropriately run the model and interpret the results.



(�3.��, ��*�� SESOIL is a one-dimensional vertical transport model for the unsaturated soil zone. SESOIL can consider only one chemical at a time and the model is based on mass balance and equilibrium partitioning of the chemical between different phases (dissolved, sorbed, vapor, and pure). The SESOIL model was designed to perform long-term simulations of chemical transport and transformations in the soil. The model uses theoretically derived equations to represent water transport, sediment transport on the land surface, contaminant transformation, and migration of the contaminant to the atmosphere and groundwater. Climatic data, compartment geometry, and soil and chemical property data are the major components used in the equations. The expression “long term” applies to both annual and monthly simulations in SESOIL, and is used in contrast to “short-term” models which employ a storm-by-storm resolution. Some soil models are designed to estimate contaminant distribution in the soil after each major storm event, and determine chemical concentrations in the soil on a daily basis (e.g., see Patterson et al., 1984). These models are data intensive, requiring, for example, hourly rainfall input and daily maximum and minimum temperatures. SESOIL, on the other hand, estimates contaminant distribution in the soil column and on the watershed after a “season”, which can be defined by the user as a year or a month. This is accomplished using a statistical water balance analysis and a washload routine statistically driven within the season. This approach saves time for the user by reducing the amount of data that must be provided, and also reduces computer time and resource requirements since fewer computations are required. Two operation options are available for running SESOIL: annual estimates (Option A) requiring annual climatic data, and monthly estimates (Option M) requiring monthly data. It is recommended that the monthly option always be selected as it will provide a better estimate of chemical movement through the soil. Option A will not be discussed further in this report with the exception of the hydrologic cycle, which implements the annual algorithm as described below. The annual option has not been changed from the original model, and those users interested in the annual option are referred to the report by Bonazountas and Wagner (1984).

When used within SEVIEW, all SESOIL runs are performed using the monthly option.

The processes modeled by SESOIL are categorized into three cycles: hydrology, sediment, and contaminant transport. Each cycle is a separate sub-model within the SESOIL code. Most mathematical environmental simulation models may be categorized as stochastic or deterministic models. Both the stochastic and deterministic models are theoretically derived. Stochastic models incorporate the concept of probability or some other measure of uncertainty, while deterministic models describe the system in terms of cause/effect relationships. SESOIL employs a stochastic approach for the hydrologic and washload cycles, and a deterministic approach for the pollutant transport cycle.



A2.1 The Soil Compartment

In SESOIL, the soil compartment (or column) is a cell extending from the surface through the unsaturated zone to the upper level of the saturated soil zone, also referred to as the aquifer or groundwater table. While SESOIL estimates the contaminant mass entering groundwater, the saturated zone is not modeled. The output from SESOIL can be used for generating input values for groundwater transport models to simulate chemical movement in the saturated zone.

SEVIEW provides a link to the AT123D and BIOSCREEN saturated zone transport and fate models.

The soil compartment is treated differently by the hydrologic cycle and the pollutant cycle in SESOIL. In the hydrologic cycle, the whole soil column is treated as a single homogeneous compartment extending from the land surface to the water table. The pollutant cycle breaks the soil column into several compartments, also called layers. The layers in the pollutant cycle can be further broken up into sub-layers. Each soil layer (sub-layer) is considered as a compartment with a set volume and the total soil column is treated as a series of interconnected layers (sub-layers). Each layer (sub-layer) can receive and release contaminants to and from adjacent layers (sub-layers).

The dimensions of the soil compartment are defined by the user. The width and length of the column are defined as the area of application of contaminant released to the soil, and the depth to the groundwater is determined from the total thickness of user-defined soil layers that are used in the pollutant cycle. The soil column can be represented in 2, 3, or 4 distinct layers. Up to 10 sub-layers can be specified for each layer, each having the same soil properties as the layer in which they reside.

There is no optimal areal size for the soil layers (sub-layers); the dimensions of the soil column can be specified to cover any area from one square centimeter to several square kilometers. The area of the compartments is important for mass balance, but in terms of contaminant concentrations the area of the soil column is irrelevant since it is constant for all layers (sub-layers). Note that the equations in SESOIL have been normalized to an area of one square centimeter.

Depending on the application, layer thicknesses can range from a shallow root zone of 5-25 centimeters, to a deep layer of more than 10 meters. It is suggested that the minimum thickness of a layer is one centimeter. When a contaminant enters a layer or sub-layer, the model assumes instantaneous and uniform distribution of the chemical throughout that layer or sub-layer. The model performs mass balance calculations over each entire soil layer (sub-layer); there is no concentration gradient within a layer (sub-layer). For a given amount of chemical released, the larger the layer (sub-layer), the lower the calculated chemical concentration. For this reason, SESOIL was discretized to allow as many as ten sub-layers in each of the four possible major layers. Thus, the user may define as many as 40 smaller compartments using these sub-layers. The result is an increase in the resolution of the model.



A2.2 SESOIL Cycles

Contaminant transport and fate in the unsaturated soil zone is controlled by complex processes affected by chemical, soil, and hydrogeological properties. In SESOIL, these processes are included in one of three cycles: the hydrologic cycle (moisture movement or flow through the compartment), the sediment or washload cycle (soil erosion), and the pollutant fate cycle (contaminant transport and fate). SESOIL integrates the three sub-models, in to one. The specific processes associated with each cycle are accounted for in the sub-models. The cycles and their associated processes are summarized in Table 16. Figure A2.1 shows a schematic of the soil column.

Table 16 SESOIL Cycles

Hydrologic Cycle • Rainfall • Infiltration • Groundwater runoff (recharge) • Surface runoff • Capillary rise • Evapotranspiration • Soil moisture retention (storage)

Sediment Cycle • Sediment washload (erosion due to storms)

Pollutant Fate Cycle • Advection • Cation exchange • Diffusion (air phase) • Volatilization • Sorption • Hydrolysis • Washload • Surface runoff • Leaching to groundwater • Metal complexation • Chemical degradation/decay

The hydrologic cycle is completed first in SESOIL, followed by the sediment cycle, and these results are used in the pollutant fate cycle. The hydrologic cycle is based on a statistical, dynamic formulation of a vertical water budget. It has been adapted to account for either yearly or monthly simulations and for moisture variations in the soil. The hydrologic cycle controls the sediment cycle, which is a theoretical monthly washload routine. The pollutant cycle simulates transport and transformation processes in three phases present in the soil compartment: soil-air or gaseous phase, soil-moisture phase, and adsorbed or soil-solids phase. The three major cycles are summarized in the sections that follow.



Figure A2.1 Schematic of the Monthly Hydrologic Cycle

Precipitation

� � � � � � �

Surface Water Runoff �

Evapotranspiration � � � � � �

� � � �

Soil Surface

(Erosion) � � � � � � � � � � �

� � � � �

Soil Moisture Retention

� � � �

� � � � � �

� SESOIL Compartment Groundwater Table

� � � � �

Groundwater Runoff

(Groundwater Recharge)

A2.3 Hydrologic Cycle

The hydrologic cycle is one-dimensional (considers vertical movement only) and focuses on the role of soil moisture (or interstitial pore water) in the soil compartment. The hydrologic cycle sub-model calculates results for the hydrology of a site and passes these results to both the sediment washload cycle and the pollutant fate cycle. The hydrologic cycle used in SESOIL is an adaptation of the water balance dynamics theory of Eagleson (1978). The theory can be described as a dimensionless analytical representation of an annual water balance. It is itself a model based on simplified models of interacting hydraulic processes, including terms for the climate, soil, and vegetation. These processes are coupled through statistically based modeling. A schematic of the hydrologic cycle is presented in Figure A2.1.



It is beyond the scope of this guide to present the detailed physics and mathematical expressions of the model. The hydrologic cycle is thoroughly described by Eagleson (1978) and summarized by Bonazountas and Wagner (1984), and is based on the water balance equations shown below. All of these parameters are expected or mean annual values, and in SESOIL they are expressed in centimeters.

P E MR S G Y− − = + = (A1)

I P S= − (A2)

Where:

Parameter Description P Precipitation E Evapotranspiration

MR Moisture retention S Surface runoff I Infiltration Y Yield G Groundwater runoff or recharge (includes term for capillary rise)

Precipitation is represented by Poisson arrivals of rectangular gamma-distributed intensity pulses that have random depth and duration. Infiltration is described by the Philip equation (Philip, 1969), which assumes the medium to be effectively semi-infinite, and the internal soil moisture content at the beginning of each storm and inter-storm period to be uniform at its long-term average. Percolation to the groundwater is assumed to be steady throughout each time step of the simulation, at a rate determined by the long-term average soil moisture content. Capillary rise from the water table is assumed to be steady throughout the time period and to take place to a dry surface. The work of Penman (1963), Van den Honert (1948), and Cowan (1965) is employed in calculating evapotranspiration (Eagleson, 1978). Surface runoff is derived from the distribution of rainfall intensity and duration, and by use of the Philip infiltration equation. The effects of moisture storage are included in the monthly option in SESOIL, based on the work of Metzger and Eagleson (1980). Eagleson's theory assumes a one-dimensional vertical analysis in which all processes are stationary in the long-term average. The expression “long term” applies to both annual and monthly simulations in SESOIL, and is used in contrast to “short-term” models which employ a storm-by-storm resolution. Also, Eagleson's approach assumes that the soil is homogeneous and that the soil column is semi-infinite in relation to the surface processes. Thus, in the hydrologic cycle of SESOIL, the entire unsaturated soil zone is conceptualized as a single layer (or compartment) and the prediction for soil water content is an average value for the entire unsaturated zone.



While the user can provide varying permeability values as input for each of the four major soil layers for the pollutant cycle in SESOIL, the hydrologic cycle will compute and use the depth-weighted average permeability according to the formula:

KddK

zi

ii

n=

−�

1

(A2)

Where:

Parameter Description Kz Vertical averaged permeability (cm2), Ki Permeability of layer i (cm2), d Depth from surface to groundwater (cm), di Thickness of layer i (cm)

Thus, the user should exercise care when applying SESOIL to sites with large vertical variations in soil properties. The average permeability calculated by Equation A2 in the hydrologic cycle may not be what the user intended and the resulting computed average soil moisture content may not be valid. There is no explicit consideration of snow and ice, which are entered as precipitation. The model assumes that the water table elevation is constant with no change in groundwater storage from year to year. Bonazountas et al. (1984) adopted this theory for both annual and monthly simulations. The process in Equations A1 and A2 are written in terms of the soil moisture content, and solution of the equations is accomplished by iterating on soil moisture until the calculated value for precipitation is within 1.0% of the input value. When this iteration is complete, the components such as infiltration, evapotranspiration, etc., in Equations A1 and A2 are also established. SESOIL uses this procedure in both the annual and monthly routines. The monthly routine is an extension of the annual routine; both are discussed further below.

A2.3.1 Annual Cycle

The annual water balance routine is based on Eagleson's (1978) theory. It encompasses one year, so multiple years have to be simulated as separate cycles. This routine simply determines the soil moisture content based on solution to Equations A1 and A2 using annual climatic parameters. When the value for soil moisture content is arrived at through the iteration technique, the various processes described in Equations A1 and A2 are established. The theoretical basis for the annual dynamic hydrologic cycle used in SESOIL has been validated by Eagleson (1978). Annual model predictions were compared with empirical observations for five years of precipitation data at both a subhumid and arid climate location, with close agreement.

The storage effects in the soil are not considered in the annual option.



A2.3.2 Monthly Cycle

The monthly water balance routine is based on the same theory as the annual routine, with modifications made to the details of moisture transfer from month-to-month (handling of moisture storage), and the radiation effects. The initial value for soil moisture content is calculated in SESOIL by summing the appropriate monthly climatic input data (for the first year) to obtain annual values and using the annual cycle algorithm. For each month the values for precipitation, mean storm number, and mean length of the rain season are multiplied by 12 in order to obtain "annual" values. Equations A1 and A2 are solved to compute the soil moisture content. Results for the components (infiltration, evapotranspiration, etc.) are divided by 12 to attain average monthly values. Note that if long-term average climatic data are used as input for each year (input for each month is the same from year to year), one would expect that the results for the hydrology for each month would be identical from year to year. However, since the initial soil moisture content is computed as stated above for the first month (of the first year), this value will be different than the soil moisture calculated for the twelfth month that is used for the first month of the following year. Thus, hydrology results will not be identical for the first two years, however, they will be identical thereafter. The monthly cycle in SESOIL does account for the change in moisture storage from month to month, incorporating the work of Metzger and Eagleson (1980). Also, the SESOIL evapotranspiration algorithm has been modified from the original work of Eagleson (1978) to include seasonal changes in average monthly radiation (radiation was a constant function of latitude before). Hetrick (1984) observed that hydrology predictions of the original SESOIL were insensitive to seasonal changes in meteorological data. To model the hydrology more realistically, an algorithm from the AGTEHM model (Hetrick et al., 1982) which computes daily potential radiation (incoming radiation for cloudless skies) for a given latitude and Julian date (December 31 = 365) is now used. The middle day of the month is used in the algorithm and the effect of cloud cover is calculated with the expression (Hetrick et al., 1982):

( )[ ]S S C kC= − +1 (A4)


S Average monthly radiation, S Potential radiation, C Fraction of sky covered by clouds, and K Transmission factor of cloud cover.

The value for k used in the models 0.32, suggested by Hetrick et al. (1982). Since latitude and monthly cloud cover are required input for SESOIL, no new input data are needed to support this modification. There are now more pronounced monthly changes in evapotranspiration predictions (see Hetrick et al., 1986).



Although SESOIL does produce monthly results for soil moisture content of the root zone, defined in the model as the first 100 cm depth from the surface, this option has not been fully developed. Thus, values for soil moisture for the root zone will usually be identical to those for the entire soil column, and only very dry climates may cause a difference (M. Bonazountas, personal communication, 1986).

SESOIL model predictions (using the monthly option) of watershed hydrologic components have been compared with those of the more data intensive terrestrial ecosystem hydrology model AGTEHM (Hetrick et. al., 1982) as well as to empirical measurements at a deciduous forest watershed and a grassland watershed (see Hetrick et al., 1986). Although there were some differences in monthly results between the two models, good agreement was obtained between model predictions for annual values of infiltration, evapotranspiration, surface runoff, and groundwater runoff (recharge). Also, SESOIL model predictions compared well with the empirical measurements at the forest stand and the grassland watersheds.

A2.3.3 Hydrologic Model Calibration

Calibration of unsaturated soil zone models can be uncertain and difficult because climate, soil moisture, soil infiltration and percolation are strongly interrelated parameters that are difficult and expensive to measure in the field. However, if at all possible, input parameters for any unsaturated soil zone model should be calibrated so that hydrologic predictions agree with observations. In SESOIL, all input parameters required for the hydrologic cycle can be estimated from field studies with the exception of the soil pore disconnectedness index. This parameter is defined as the exponent relating the “wetting” or “drying” time-dependent permeability of a soil to its saturated permeability (Eagleson, 1978; Eagleson and Tellers, 1982). Brooks and Corey (1966) presented the following relationship:

( ) ( )K S K S c= 1 (A5) Where:

Parameter Description K(1) Saturated hydraulic conductivity (cm/s), K(S) Hydraulic conductivity at S (cm/s),

S Percent saturation, c Soil pore disconnectedness index.

This parameter is not commonly found in the literature. Default values for soil pore disconnectedness index suggested by Eagleson (1978) and Bonazountas and Wagner (1981, 1984) are: clay 12; silty clay loam 10; clay loam 7.5; silt loam 5.5; sandy loam 6; sandy clay loam 4; and sand 3.7 (see Section 6.5). However, when data are available, this parameter should be varied first to optimize agreement between SESOIL results and hydrologic measurements. It should be noted that most unsaturated soil zone models require detailed data (which are difficult to obtain), such as soil moisture characteristic curves. The “one variable” approach of Eagleson (1978) simplifies the data estimation process and reduces computational time.



Other sensitive parameters for the hydrologic cycle are the effective porosity and the intrinsic permeability (e.g., see Hetrick et al., 1986, 1989). While other parameters can be varied when calibrating the model to measured hydrologic data, it is recommended that the user vary the soil pore disconnectedness index first, followed by the permeability and/or porosity. See Section 6.5 for additional information on required soil property parameters.

A2.4 Sediment Washload Cycle

The SESOIL sediment cycle is optional.

In contaminant transport models, estimates of erosion and sediment yield on watersheds may be needed in order to compute the removal of sorbed chemicals on eroded sediments. A major factor in this process is the surface runoff, rainwater which does not infiltrate the soil and may carry dissolved contaminant. Surface runoff is computed as part of the hydrologic cycle. Erosion is a function of the rate of surface runoff and several other factors. These factors include the impact of raindrops which detaches soil particles and keeps them in motion as overland flow, surface features such as vegetation and roughness, and infiltration capacity. Because of the difficulty in directly measuring washload using water quality monitoring techniques, estimation techniques and models are widely employed.

If contaminant erosion (surface runoff) is considered negligible, the washload cycle can be neglected. If the option is used, SESOIL employs EROS, a theoretical sediment yield model (Foster et al., 1980), which is part of CREAMS model (Knisel, 1980; Foster et al., 1980). The erosion component considers the basic processes of soil detachment, transport, and deposition. The EROS model uses separate theoretically derived equations for soil detachment and sediment transport. Separate equations are needed for these two processes because the relationship of the detachment process to erosion is different than the relationship between erosion and transport.

For the detachment process, the model employs the Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1978), modified by Foster et al. (1980) for single storm events. The USLE is applicable for predictions of annual sediment erosion originating mainly from small watersheds which are subject to sheet and rill erosion. Detachment of soil particles occurs when the sediment load already in the overland flow is less than the sediment capacity of this flow. The equation takes into account soil erodibility (the rate of soil loss per storm), which varies for different soil types and texture classes. The USLE considers topography, since both the length and the steepness of the land slope affect the rate of rain-induced soil erosion. Also, the land cover (e.g. vegetation) and the roughness of the soil surface affect the rate of erosion and the rate of overland transport. The USLE includes a parameter called “Manning's n”, or roughness coefficient, to model these influences.

To model the sediment transport capacity for overland flow, EROS incorporates the Yalin Transport Equation (Yalin, 1963), modified for non-uniform sediment with a mixture of particle sizes and densities. The model estimates the distribution of sediment particles transported as sand, silt, and clay, and the fraction of organic matter in the eroded sediment. SESOIL computations of sediment transport are performed for each particle size type, beginning at the upper end of a slope and routing sediment down slope.



The EROS model in SESOIL accounts for several surface features which may divert and slow the overland flow, allowing settling and deposition of the washload. These include vegetation, which slows the flow and filters out particles, and topography, which includes surface characteristics such as roughness and the existence of small depressions. Change in slope and loss of water through infiltration into the soil will reduce the flow rate and encourage settling of soil particles. Organic matter is distributed among the particle types based on the proportion of primary clay in each type (Foster et al., 1980). Soil receiving the deposited sediment is referred to as enriched. EROS computes sediment enrichment based on the ratio of the surface area of the sediment and organic matter to that of the surface area of the residual soil (Knisel et al., 1983).

A2.4.1 Implementation in SESOIL

The EROS model uses characteristic rainfall and runoff factors for a storm to compute erosion and sediment transport for that storm (Foster et al., 1980). Hydrologic input to the erosion component consists of rainfall volume, rainfall erosivity, runoff volume, and the peak rate of runoff for each storm event. These terms drive soil detachment and subsequent transport by overland flow. Note that input data for the hydrologic cycle of SESOIL includes total monthly precipitation, the number of storms per month, and the mean duration of each rainfall event. Since SESOIL provides only monthly estimates of hydrologic parameters and in order to couple the SESOIL and EROS models, a statistical method is used to generate the amount of rainfall and duration of each storm for every rainfall event during the month. This algorithm employs a model featuring probability distributions in order to estimate the individual storm parameters (Eagleson, 1978; Grayman and Eagleson, 1969).

The washload cycle has been implemented with two subroutines in addition to the EROS; model PARAM and STORM, which take the input data for and results generated by the hydrologic cycle and adapt them for use. The PARAM subroutine supports EROS by first retrieving the hydrologic input data (e.g. the number of storm events per month and the depth of rainfall) read by SESOIL and then setting specific parameters applicable to the STORM and EROS subroutines. The STORM subroutine then uses the PARAM results and statistically generates information about each storm using the algorithm mentioned above. Thus, the coupled SESOIL EROS model does not require any additional hydrologic input parameters for individual storms. However, it should be recognized that estimates of rainfall for each storm may be quite different than the actual values.

Additional data needed for the sediment cycle include the washload area, the fraction of sand, silt and clay in the soil, the average slope, slope length of the representative overland flow profile, the soil erodibility factor, the soil loss ratio, the contouring factor, and Manning's n coefficient for soil cover and surface roughness. Example values for these parameters can be found in the CREAMS documentation (Knisel, 1980; Foster et al., 1980). Note that the washload area should be less than or equal to the pollutant application area.

EROS takes the information generated by both the PARAM and STORM subroutines and computes estimates of the sediment yield for each month. Information from the sediment cycle, along with information from the hydrologic cycle, is then provided to the pollutant fate cycle, which will be discussed in the next subsection.



The coupled SESOIL EROS model was evaluated by comparing predictions to published measured data (Hetrick and Travis, 1988). Two cornfield watersheds and one grassland watershed were included in the study. The sites differed in their management practices, soil type, ground cover, and meteorology. The model predictions were in fair to good agreement with observed data from the three watersheds, except for months where surface runoff came from one or two high intensity storms (Hetrick and Travis, 1988).

A2.5 Pollutant Fate Cycle

The pollutant fate cycle focuses on the various contaminant transport and transformation processes which may occur in the soil. These processes are summarized in Table 16, and are discussed in more detail in the subsections that follow. The pollutant fate cycle uses calculated results from the hydrologic cycle and the sediment washload cycle. Information from these cycles is automatically provided to the pollutant fate cycle. In SESOIL, the ultimate fate and distribution of the contaminant is controlled by the processes interrelated by the mass balance Equation A6 below. The processes are selectively employed and combined by the pollutant fate cycle based on the chemical properties and the simulation scenario specified by the user. The actual quantity or mass of contaminant taking part any one process depends on the competition among all the processes for available contaminant mass. Contaminant availability for participation in these processes, and the contaminant rate of migration to the groundwater, depends on its partitioning in the soil between the gas (soil air), dissolved (soil moisture), and solid (adsorbed to soil) phases.

A2.5.1 Foundation

In SESOIL, any layer or sub-layer can receive contamination, store it, and export it to other sub-compartments. Downward movement of a contaminant occurs only with the soil moisture, while upward movement can occur only by vapor phase diffusion. Like the hydrologic cycle, the pollutant fate cycle is based on a mass balance equation (Equation A6) that tracks the contaminant as it moves in the soil moisture between sub-compartments. Upon reaching and entering a layer or sub-layer, the model assumes instantaneous uniform distribution of the contaminant throughout that layer or sub-layer. The mass balance equation is:

( ) ( ) ( ) ( ) ( )O t l t T t R t M t− + = + +1 (A6)

Where:

Parameter Description ( )O t − 1 Amount of contaminant originally in the soil compartment at the time t-

1 (µg/cm2),

( )l t Amount of contaminant entering the soil compartment during a time step (µg/cm2),

( )T t Amount of contaminant transformed within the soil compartment during the time step (µg/cm2),

( )R t Amount of contaminant remaining in the soil compartment at time t (µg/cm2),

( )M t Amount of contaminant migrating out of the soil compartment during the time step (µg/cm2).



The fate of the contaminant in the soil column includes both transport and transformation processes, which depend on the chemical's partitioning among the three phases: soil air, soil moisture, and soil solids. The three phases are assumed to be in equilibrium with each other at all times (see Figure A2.2), and the partitioning is a function of user-supplied chemical-specific partition coefficients and rate constants. Once the concentration in one phase is known, the concentrations in the other phases can be calculated. The pollutant cycle of SESOIL is based on the chemical concentration in the soil water. That is, all the processes are written in terms of the contaminant concentration in soil water and the model iterates on the soil moisture concentration until the system defined by Equation A6 balances.

Figure A2.2 Schematic of Chemical Phases in the Soil Matrix

Volatilization � � � � �

Soil Surface

Upper Soil Layer (or Upper Most Sub-Layer)

Chemical Load to Soil Column � � � � �

Diffusion Upwards

� � � � �

Middle Soil Layers and Soil Sub-Layers

� � � � �

Downward Transport

Diffusion Upwards

� � � � �

� SESOIL Compartment

Lower Soil Layer (or Lower Most Sub-Layer)

� � � � �

Downward Transport

� � � � �

Groundwater Table

� � � � � Leaching to Groundwater



The contaminant concentration in soil air is calculated via the modified Henry's law:

( )CcH

R Tsa =+ 273

(A7)

Where:

Parameter Description Csa Contaminant concentration in soil air (µg/ml), c Contaminant concentration in soil water (µg/ml), H Henry’s law constant (m3 atm/mol), R Gas constant [8.2 E 10-5 m3 atm/(mol º K)], and T Soil temperature (º C).

The concentration adsorbed to the soil is calculated using the Freundlich isotherm (note that a cation exchange option, discussed later, is available in SESOIL),

s K cdn=1

(A8) Where:

Parameter Description s Contaminant adsorbed concentration (µg/g),

Kd Contaminant distribution coefficient (µg/g)/ (µg/ml), c Contaminant concentration in soil water (µg/ml), n Freundlich exponent.

The total concentration of the contaminant in the soil is computed as:

c f c c so a sa b= + +θ ρ (A9)

Where:

Parameter Description Co Overall (total) contaminant concentration (µg/cm3), fa f − θ = the air-filled porosity (ml/ml),

Csa Contaminant concentration in soil air (µg/ml), f Soil porosity (ml/ml), θ Soil water content (ml/ml), c Contaminant concentration in soil water (µg/ml),

ρ b Soil bulk density (g/cm3), and

s Adsorbed contaminant concentration (µg/g).



In SESOIL, each soil layer (sub-layer) has a set volume and the total soil column is treated as a series of interconnected layers. Each layer (sub-layer) has its own mass balance equation (Equation A6) and can receive and release contamination to and from adjacent layers (sub-layers). Again, the individual fate processes that compose the SESOIL mass balance equations (e.g., volatilization, degradation) are functions of the contaminant concentration in the soil water of each zone and a variety of first-order rate constants, partitioning coefficients, and other constants. An iterative solution procedure is used to solve the system (the iteration parameter is the soil pore disconnectedness index). See Bonazountas and Wagner (1984) for the numerical solution procedure. The pollutant cycle equations are formulated on a monthly basis and results are given for each month simulated. However, to account for the dynamic processes in the model more accurately, an explicit time step of 1 day is used in the equations. The monthly output represents the summation of results from each day. In the event that the dissolved concentration exceeds the aqueous solubility of the contaminant, the dissolved concentration is assumed to equal the aqueous solubility. That is, if during solution of the mass balance equation for any one layer, the dissolved concentration exceeds the solubility of the chemical, the iteration is stopped for that time step and the solubility is used as the dissolved concentration. The adsorbed and soil-air concentrations are calculated using the chemical partitioning equations as before (Equations A7 and A8). To maintain the mass balance, the remaining contamination is assumed to remain in a pure phase (undissolved). Transport of the pure phase is not considered, but the mass of the chemical in the pure phase is used as input to that same layer in the next time step. Simulation continues until the pure phase eventually disappears. The pure phase capability was not part of the original model and was added to SESOIL by Hetrick et al. (1989). The discussion in the subsections that follow introduces the user to major algorithms and processes simulated in the pollutant cycle of SESOIL.

A2.5.2 The Contaminant Depth Algorithm

The pollutant cycle in SESOIL is based on the contaminant concentration in soil moisture. In theory, a non-reactive dissolved contaminant originating in any unsaturated soil layer will travel to another soil layer or to the groundwater at the same speed as the moisture mass originating in the same soil layer. The movement of a reactive contaminant however, will be retarded in relation to the movement of the bulk moisture mass due to vapor phase partitioning and the adsorption of the contaminant on the soil particles. If it is assumed that no adsorption occurs, and the vapor phase is negligible, the contaminant will move at the same rate as water through the soil. Originally, only the advective velocity was used in SESOIL to determine the depth the contaminant reached during a time step. The depth (D) was calculated as:



DJ tw c=θ

(A10)

Where:

Parameter Description D Contaminant depth, Jw Water velocity (cm/s), tc Advection time (s), and θ Soil water content (cm3/cm3)

This approach allows all chemicals to reach the groundwater at the same time; irrespective of their chemical sorption characteristics. To account for retardation, SESOIL now uses the following equation to calculate the depth reached by a chemical with a linear equilibrium partitioning between its vapor, liquid, and adsorbed phases (Jury et al., 1984):

( )D

J t

Kf H

R T

w c

b da

=+ +

+θ ρ

273

(A11)

Where:

Parameter Description D contaminant depth, Jw Water velocity (cm/s), tc Advection time (s), and θ Soil water content (cm3/cm3) ρ b Soil bulk density (g/cm3)

Kd Chemical distribution coefficient (µg/g)/ (µg/ml), fa f − θ = the air-filled porosity (ml/ml), H Henry’s law constant (m3 atm/mol), R Gas constant [8.2 X 10-5 m3 atm/(mol º K)], and T Soil temperature (º C).

SESOIL calculates the flux Jw for each layer using the infiltration rate and groundwater runoff (recharge) rate computed by the hydrologic cycle, and the depths and permeabilities input by the user. Note that a different permeability can be input for each of the four major soil layers. While the hydrologic cycle will use the depth weighted mean average of layer permeabilities according to Equation A2, the pollutant cycle does take into account the separate permeability for each layer in computing Jw at the layer boundaries according to the following equation:



( )J G I Gd

dkKw z

j i

z

, = + − �

��

�

��

�

�

��

��

�

�� (A12)

Where:

Parameter Description Jw,z Infiltration rate at depth z, which will be the boundary between two

major layers (cm/s), G Groundwater runoff (recharge) (cm/s) I Infiltration at surface (cm/s) dj Depth of soil column below depth z (cm), d Depth of soil column from surface to groundwater table (cm), Kz Intrinsic permeability (cm2), defined by Equation A2, and ki The vertical-averaged permeability for layer 1 (cm2); is computed

using Equation A2 except d in the numerator of Equation A2 is the sum of the layer depths above depth z and the summation in the denominator is from layer 1 to layer i.

The user is allowed two options for loading of a contaminant:

1. A spill loading where all the contamination is entered at the soil surface in the first time step of the month when the loading takes place, or

2. A steady application where the contaminant load is distributed evenly for each time step during the month at which the loading is specified.

Option 1 allows loading at the soil surface only (layer 1, sub-layer 1), whereas option 2 will allow loading in one or more of the four major layers. If sub-layers are specified, the loading will always be entered into the first (top) sub-layer of the major layer. While a contaminant can be loaded in each of the four major layers, the contamination can not be loaded into each sub-layer of a major layer to get a specific initial concentration distribution for the major layer. If there is a spill loading or if the contaminant is entered as a steady application in layer 1 (sub-layer 1), then the depth of the contaminant front is calculated using Equation A11 starting from the surface. If a steady loading is specified in layers 2, 3, and/or 4, then the depth of the contaminant front is assumed to begin at the middle of the lowest layer at which contaminant is loaded (sub-layer 1 of that layer if sub-layers are included) and Equation A11 is used to compute the depth of the contaminant front from that point. Subsequently, the contaminant is not allowed to enter a layer/sub-layer until the depth of the contaminant front has reached the top of that layer/sub-layer. When the contaminant depth reaches the groundwater table, contamination leaves the unsaturated zone by simply multiplying the groundwater runoff (recharge) rate by the concentration in the soil moisture.



Although a spill loading can not be used in SESOIL for layers 2, 3, or 4, an initial soil-sorbed concentration can still be approximated for these layers. See Section 6.7.3 for more information.

A2.5.3 Volatilization/Diffusion

In SESOIL, volatilization/diffusion includes movement of the contaminant from the soil surface to the atmosphere and from lower soil layers to upper ones. Note that vapor phase diffusion in SESOIL operates in the upward direction only. The rate of diffusion for a chemical is determined by the properties of the chemical, the soil properties, and environmental conditions. The volatilization/diffusion model in SESOIL is based on the model of Farmer et al. (1980) and Millington and Quirk (1961) and is a discretized version of Fick's first law over space, assuming vapor phase diffusion as the rate controlling process. That is, the same equation is used for volatilization to the atmosphere as is used for diffusion from lower layers to upper ones. The vapor phase diffusion flux through the soil Ja (µg/cm2s) is described as:

J Dff

dCdza a

a sa= −�

�

��

�

�

��

103

2 (A13)

Where:

Parameter Description Ja Vapor phase diffusion flux through the soil (µg/cm2s), Da Vapor diffusion coefficient of the compound in air (cm2/s), fa f − θ = the air-filled porosity (ml/ml), f Soil porosity (ml/ml), d Depth of soil column from surface to groundwater table (cm),

Csa Contaminant concentration in soil air (µg/ml) (from Equation A7), and dz Contaminant depth from the ground surface.

The volatilization algorithm in the original version of SESOIL allowed contaminant in the second (or lower) layer to volatilize directly to the atmosphere. This algorithm was modified by Hetrick et al. (1989). The contaminant can volatilize directly to the atmosphere from the surface layer, but if the chemical is in the second or lower layer, and the concentration in that layer is greater than the layer above it, then the chemical will diffuse into the upper layer rather than volatilize directly into the atmosphere.

An option the user has in the volatilization algorithm is to “turn off” the calculation by use of an input index parameter (for each layer). For example, if the index is set to 0.0 for each layer, the contaminant would not be allowed to diffuse upward or volatilize to the atmosphere; only downward movement of the contaminant with the soil moisture would occur. Also, if data are available, this index parameter can be varied to calibrate calculations to the measurements.



A2.5.4 Sorption Adsorption/Desorption And Cation Exchange

SESOIL includes two partitioning processes for movement of a contaminant from soil moisture to soil air or soil solids. These are the sorption process and the cation exchange mechanism. The sorption process may be defined as the adhesion of contaminant molecules or ions to the surface of soil solids. Most sorption processes are reversible; adsorption describing the movement of contaminant onto soil solids and desorption being the partitioning of the chemical from solid into the liquid or gas phase (Lyman et al., 1982). Adsorption and desorption are usually assumed to be occurring in equilibrium and are therefore modeled as a single process (Bonazountas et al., 1984). Adsorption is assumed to occur rapidly relative to the migration of the contamination in soil moisture; it can drastically retard contaminant migration through the soil column. SESOIL employs the general Freundlich equation (see Equation A8 above) to model soil sorption processes. The equation correlates adsorbed concentration with the dissolved concentration of the contaminant, by means of an adsorption coefficient and the Freundlich parameter. This equation has been found to most nearly approximate the adsorption of many contaminants, especially organic chemicals, and a large amount of data have been generated and are available in the literature (see Bonazountas and Wagner, 1984; Fairbridge and Finke, 1979; Lyman et al., 1982). For most organic chemicals, adsorption occurs mainly on the organic carbon particles within the soil (Lyman et al., 1982). The organic carbon partition coefficient (Koc) for organic chemicals can be measured or estimated (Lyman et al., 1982). Koc is converted to the distribution coefficient (Kd) by multiplying by the fraction of organic carbon in the soil. Values for the Freundlich exponent can be found in the literature. They generally range between 0.9 and 1.4, although values can be found as low as 0.3 and as high as 1.7. In the absence of data, a value of 1.0 is recommended since no estimation techniques for this parameter have yet been developed. Note that using 1.0 for the Freundlich exponent assumes a linear model for sorption (see Equation A8). The user is cautioned regarding indiscriminately using literature values for the distribution coefficient Kd or the Freundlich exponent, or estimation methods for Kd. There can be much variability in the values that are estimated or found in the literature compared to actual measurements for a site. For examples, refer to the study of Melancon et al. (1986). Another option for modeling adsorption in SESOIL uses the cation exchange capacity (CEC). Cation exchange occurs when positively charged atoms or molecules (cations such as heavy metals) are exchanged with the cations of minerals and other soil constituents. CEC is a measure amount of cations per unit of soil that are available for exchange with the contaminant.



The cation exchange algorithm in SESOIL is very simple and estimates the maximum amount of contaminant that can be adsorbed. The calculation of the contaminant immobilized by cation exchange is given by (from Bonazountas and Wagner, 1984):

MCEC a CECMWTVAL

= × × (A14)

Where:

Parameter Description MCEC Maximum contaminant cation exchanged by the soil (µg/g soil),

a Units coefficient = 10, CEC Cation exchange capacity of the soil (meg/100g of dry weight soil), MWT Molecular weight of the contaminant cation (g/mol), VAL Valence of the cation (-)

The cation exchange algorithm has been verified to be computationally correct in SESOIL, but it has not been validated with measured data.

With clay soil, the exchanged ion is often calcium, and clay soils tend to have the highest cation exchange capacity. Note that the CEC value of a soil increases with increase in pH, but pH is not included in the CEC algorithm in SESOIL. The CEC value must be adjusted manually to include effects due to pH. In SESOIL, cation exchange computed by Equation A14 is assumed to occur instantaneously, and irreversibly. Once maximum adsorption via exchange has been reached, no additional adsorption will be calculated. The process is also assumed to take precedence over all other soil processes in competition for the contaminant cation. The use of the cation exchange subroutines is optional. If it is used, Equation A8 should not be used [i.e., model inputs for the organic carbon adsorption coefficient (Koc) and soil distribution coefficient (Kd), should be 0.0] unless the user has selected the model inputs in such a way as to avoid double accounting. It is up to the user to be sure that cation exchange is the predominant adsorption mechanism at the modeled site. This determination includes considerations of leachate characteristics such as pH, ionic strength, and the presence and concentration of other cations. The other cations, often found in landfill leachate and aqueous industrial wastes, may have higher affinity for exchange with soil cations, and may effectively block exchange between the contaminant and the soil cations. In addition, the speciation of the contaminant should be considered (Bonazountas and Wagner, 1984).

A2.5.5 Degradation: Biodegradation And Hydrolysis

The pollutant cycle of SESOIL contains two transformation routines which can be used to estimate contaminant degradation in the soil. Biodegradation is the biologic breakdown of organic chemicals, most often by microorganisms. Hydrolysis is a chemical reaction of the pollutant with water. Both processes result in the loss of the original contaminant and the creation of new chemicals. The SESOIL model accounts for the mass of contaminant lost via



degradation but does not keep track of any degradation products. The user is responsible for knowing what the degradation products will be and their potential significance. The biodegradation process is usually a significant loss mechanism in soil systems since soil environments have a diverse microbial population and a large variety of food sources and habitats (Hamaker, 1972). Many environmental factors affect the rate of biodegradation in soil, including pH, moisture content of the soil, temperature, redox potential, availability of nutrients, oxygen content of the soil air, concentration of the chemical, presence of appropriate microorganisms, and presence of other compounds that may be preferred substrates. However, SESOIL does not consider these factors. Biodegradation in SESOIL is handled as primary degradation, which is defined as any structural transformation in the parent compound which results in a change in the chemical's identity. It is estimated using the chemical's rate of decay in both the dissolved and adsorbed phases according to the first-order rate equation:

( )P C k S k Ad td dl b ds s= +θ ρ ∆ (A15)

Where:

Parameter Description Pd Decayed contaminant mass during time step ∆t (µg). kdl Biodegradation rate of the compound in the liquid phase (day-1) kds Biodegradation rate of the compound in the solid phase (day-1) A Area of the contaminant application (cm3) ds Depth of the soil sub-layer (cm) ∆t Time step (day), c Contaminant concentration in soil water (µg/ml), θ Soil water content (ml/ml), and s Adsorbed contaminant concentration (µg/g).

Note that c, θ, and s are functions of time in the SESOIL model. The use of a first-order rate equation is typical for fate and transport models and generally is an adequate representation of biodegradation for many chemicals. However, due to the many factors affecting biodegradation, in some cases a first-order rate may not be applicable to the site field conditions and a zero-order or a second- or higher-order rate might be more appropriate. The biodegradation algorithm in SESOIL that is described by Equation A15 can not handle these cases. The user is cautioned regarding the use of literature values for the biodegradation rates since these values are quite variable and in many cases are not applicable to site field conditions. In most cases, biodegradation rates are very site-specific and uncertainty in these rates must be recognized. The user-supplied first-order decay rate constants (for



moisture and solids) should be values measured for the contaminant in a soil culture test under conditions similar to the site being modeled. The SESOIL hydrolysis algorithm allows the simulation of neutral, acid- or base-catalyzed reactions and assumes that both dissolved and adsorbed contaminants are susceptible to hydrolysis (Lyman et al., 1982). Since hydrolysis is the reaction of the contaminant with water, this reaction may occur at any depth as the contaminant moves through the soil column. The hydrolysis subroutine requires user-supplied rate constants for the neutral, acid and base hydrolysis reactions of the contaminant, and the pH for each soil layer. The model does not correct for the temperature of the modeled soil.

The hydrolysis algorithm has been verified but has not been validated. As for the biodegradation process, the algorithm for hydrolysis uses Equation A15 except the rates kdl and kds are both replaced by the rate constant kh defined as (from Bonazountas and Wagner, 1984):

[ ] [ ]k k k H k OHh o H OH= + ++ − (A16)

Where:

Parameter Description kh Hydrolysis rate constant (day-1), ko Rate constant for neutral hydrolysis (day-1), kH Rate constant for acid-catalyzed hydrolysis (days-1 mol-1 liter),

[H+] 10-pH, the hydrogen ion concentration (mol/l), kOH Rate constant for base-catalyzed hydrolysis (days-1 mol-1 liter), and

[OH-] 10pH-14, the hydroxyl ion concentration (mol/l). If cation exchange is considered, the following formula is used:

P MCECk Ad td h b s= ρ ∆ (A17) Where:

Parameter Description MCEC Maximum contaminant cation exchanged by the soil (µg/g soil),

kh Hydrolysis rate constant (day-1), ρ b Soil bulk density (g/cm3),

A Area of the contaminant application (cm3), ds Depth of the soil sub-layer (cm), and ∆t Time step (day).



Extrapolating hydrolysis rates measured in a laboratory to the environment increases the uncertainty of model results if the hydrolysis rate is not corrected for the influences of temperature, adsorption, the soil ionic strength, and the possible catalytic effect of dissolved material or solid surfaces. Since there are usually large uncertainties in hydrolysis rates, the SESOIL model results for hydrolysis should be considered only as approximations. The rate of hydrolysis for various organic chemicals may vary over more than 14 orders of magnitude. In addition, the hydrolysis routine does not consider the influence of ionic strength or the presence of other dissolved organics on the hydrolysis rate of the contaminant.

A2.5.6 Metal Complexation

Complexation, also called chelation, is defined here as a transformation process. In SESOIL, complexation incorporates the contaminant as part of a larger molecule and results in the binding of the contaminant to the soil. For example, metal cations (e.g. copper, lead, iron, zinc, cadmium) combine with organic or other nonmetallic molecules (ligands) to form stable complexes. The complex that is formed will generally prevent the metal from undergoing other reactions or interactions of the free ion.

The complexation routine has been verified but has not been validated. The pollutant fate cycle incorporates a simplified representation of the complexation process as a removal process. It is only available for scenarios in which the contaminant is a heavy metal. The model assumes a reversible process in which a metal ion is complexed by a specified soluble organic ligand to form a complex which is soluble, non-absorbable, and non-migrating. Possible ligands are humic acid, fulvic acid, and low molecular weight carboxylic acids, which are commonly found in landfill leachate (Bonazountas and Wagner, 1984). It is the responsibility of the user to determine whether this process is likely to occur in the scenario being modeled, and to supply the appropriate information. The complexation subroutine employs a nonlinear equation which must be solved numerically. It uses the same iterative procedure as the general pollutant cycle for monthly simulations. Required data include the stability (or dissociation) constant for the specific complex, and the mole ratio of ligand to metal. Also required are the molecular weights of the metallic contaminant and the organic ligand. Equations used by this subroutine are based on the work of Giesy and Alberts (1984), Brinkman and Bellama (1978), and Sposito (1981). The model does not consider competition with metal ions in the soil which may have higher affinity for the ligand. Note that if the user chooses to model both cation exchange and metal complexation, the cation exchange process is assumed to occur first; ions involved in cation exchange are then unavailable for complexation. The general adsorption processes are modeled as being competitive with the complexation process (Bonazountas and Wagner. 1984).



A2.5.7 Contamination In Surface Runoff And Washload

Contaminant mass can be removed from the soil area being simulated by SESOIL via surface runoff and washload. The contamination in surface runoff is simply the surface runoff computed in the hydrologic cycle (for each month) multiplied by the contaminant concentration in the soil moisture of the surface layer (for each time step). The result of this calculation is multiplied by the index of contaminant transport in surface runoff (ISRM), which controls the amount of chemical partitioned into runoff. There is no basis for estimating the index of contaminant transport in surface runoff; it can be set to 0.0 to “turn off” the contaminant participation in runoff, or it can be used essentially as a fitting parameter if data are available. In a calibration/validation exercise used to predict atrazine runoff at a site in Watkinsville, Georgia, the index of contaminant transport in surface runoff was found to be 0.06 (see Hetrick et al., 1989).

See Section 6.7.3 for additional information on the index of contaminant transport in surface runoff (ISRM).

Contaminant loss via washload is computed by taking the sediment yield from the washload cycle multiplied by the adsorbed contaminant concentration in the surface layer. While studies have been conducted comparing results of sediment yield with field data (Hetrick and Travis, 1988), contaminant loss via washload has not been validated in SESOIL.

A2.5.8 Soil Temperature

The original SESOIL model assumed that soil temperature was equal to the user-supplied air temperature. The model was modified by Hetrick et al. (1989) to predict soil temperature from air temperature according to the following (Toy et al., 1978):

Summer: Y = 16.115 + 0.856X, Fall: Y = 1.578 + 1.023X, Winter: Y = 15.322 + 0.656X, Spring: Y = 0.179 + 1.052X,

Where:

Parameter Description Y Mean monthly soil temperature (°F). X Mean monthly air temperature (°F).

These regression equations are very crude and not depth dependent. However, further complexity is not warranted since soil temperature is used only in Equation A7 and does not significantly affect results. It should be noted that some chemical parameters and processes are dependent on temperature (for example, solubility, Henry's law constant, and rate constants for biodegradation and hydrolysis). No explicit consideration of these effects is included in SESOIL, and the user should adjust the input values for such parameters if temperature effects are judged to be important.



A2.5.9 Pollutant Cycle Evaluation

There are several approaches used to evaluate the reliability and usefulness of an environmental model, such as verification, calibration, sensitivity analysis, uncertainty analysis, and validation. Verification establishes that results from each of the algorithms of the model are correct. Calibration is the process of adjusting selected model parameters within an accepted range until the differences between model predictions and field observations are within selected criteria of performance (Donnigan and Dean, 1985). Sensitivity analysis focuses on the relative impact each parameter or term has on the model output, in order to determine the effect of data quality on output reliability. Uncertainty analysis seeks to quantify the uncertainty in the model output as a function of uncertainty in both model input and model operations. Validation also compares measured with predicted results, but includes analysis of the theoretical foundations of the model, focusing on the model's performance in simulating actual behavior of the chemical in the environment under study. (Note that the term validation has often been broadly used to mean a variety of things, including all five of the techniques mentioned above.) A number of calibration, validation, and sensitivity studies have been performed on the SESOIL model. The model has been verified by extensive testing using extreme ranges of input data. Studies of the hydrologic and washload cycles have already been discussed above (see Sections A2.3 and A2.4). The following discusses the kinds of evaluations that have been performed on the pollutant cycle of the SESOIL model. Note that model validation is a continuing process; no model is ever completely validated. To assess SESOIL’s predictive capabilities for contaminant movement, a contaminant transport and validation study was performed by Arthur D, Little, Inc. under contract to EPA (Bonazountas et al., 1982). The application/validation study was conducted on two field sites, one in Kansas and one in Montana. SESOIL results were compared to data for the metals chromium, copper, nickel, and sodium at the Kansas site and the organics naphthalene and anthracene at the Montana site. Results showed reasonable agreement between predictions and measurements, although the concentrations of the metals were consistently underestimated, and the rate of metal movement at the Kansas site was consistently overestimated. At the Montana site, the concentrations of the organics were overestimated by SESOIL. Bonazountas et al. (1982) state that the over estimations for the organics were probably due to the fact that biodegradation was not considered in the simulations. Note that this study was done with the original SESOIL model, not the modified model that is described herein. Hetrick et al. (1989) compared predictions of the improved version of SESOIL with empirical data from a laboratory study involving six organic chemicals (Melancon et al., 1986) and from three different field studies invoking the application of aldicarb to two field plots (Homsby et al., 1983; R. L. Jones, 1986; Jones et al., 1983, 1985) and atrazine to a single-field watershed (Smith et al., 1978). Results for several measures of contaminant transport were compared including the location of chemical peak vs. time, the time-dependent amount of contaminant leached to groundwater, the depth distribution of the contaminant at various times, the mass of the chemical degraded, and the amount



of contaminant in surface runoff. This study showed that SESOIL predictions were in good agreement with observed data for both the laboratory study and the field studies. SESOIL does a good job of predicting the leading edge of the chemical profile (Hetrick et. al., 1989), due mainly to the improvement of the contaminant depth algorithm to include the chemical sorption characteristics (see Section A2.5.2 above). Also, when a split-sample calibration/validation procedure was used on 3 years of data from the single-field watershed, SESOIL did a good job of predicting the amount of chemical in the runoff. The model was less effective in predicting actual concentration profiles; the simulated concentrations near the soil surface under estimated the measurements in most cases. One explanation is that SESOIL does not consider the potential upward movement of the chemical with the upward movement of water due to soil evaporation losses. SESOIL is a useful screening-level chemical migration and fate model. The model is relatively easy to use, the input data are straight forward to compile, and most of the model parameters can be readily estimated or obtained. Sensitivity analysis studies with SESOIL can be done efficiently. SESOIL can be applied to generic environmental scenarios for purposes of evaluating the general behavior of chemicals. Care should be taken when applying SESOIL to sites with large vertical variations in soil properties since the hydrologic cycle assumes a homogeneous soil profile. Only one value for the soil moisture content is computed for the entire soil column. If different permeabilities are input for each soil layer, the soil moisture content calculated in the hydrologic cycle using the vertically-averaged permeability (Equation A2) may not be valid for the entire soil column. Thus, the user is warned that even though the model can accept different permeabilities for each layer, the effects of variable permeability are not fully accounted for by the model. It is recommended that predictions for the hydrology at a given site be calibrated to agree with known measurements. Caution should be used when making conclusions based on modeling results when little hydrologic data exist against which to calibrate predictions. In these cases, it is recommended that the user employ sensitivity analysis or evaluate results obtained by assigning distributions to the input parameters (e.g., see Gardner, 1984; O'Neill et al., 1982; Hetrick et al., 1991). However, when properly used, SESOIL is an effective screening-level tool in assessing chemical movement in soils.



( 3.��*��

This section provides a description of the SESOIL input parameters. SESOIL uses ASCII text files to store the information used in the model scenarios. These files must be formatted so that the SESOIL program correctly read the data. A description of the FORTRAN read format is also provided.

SESOIL Climate Data Parameters

Line 1

NRE Climate Data Set Title IYRS 5 6 54 59

Parameter Format Description

NRE I5 Index number for the climate data set TITLE A48 Climate data set title IYRS I5 Number of years of climate data in the data set

Skip Line 2 Lines 3 to 11

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep 8 14 20 26 32 38 44 50 56 62 68 74 80 Line Parameter Format Description

3 TA F6.2 Monthly mean air temperature (Celsius) 4 NN F6.2 Monthly mean cloud cover 5 S F6.2 Monthly mean relative humidity 6 A F6.2 Monthly short wave albedo fraction 7 REP F6.2 Monthly mean evapotranspiration rate (cm/day) 8 MPM F6.2 Monthly precipitation (cm) 9 MTR F6.2 Monthly mean duration of individual storms (days) 10 MN F6.2 Monthly number of storm events 11 MT F6.2 Monthly length of rainy season (days)

Line 12

NRE 5 Parameter Format Description

NRE I5 End of climate data file when NRE = 999



SESOIL Chemical Data Parameters Line 1

NCH Chemical Data Set Title 5 6 54


NCH I5 Index number for the chemical data set TITLE A48 Chemical data set title

Line 2

SL DA H KOC K 38 45 52 59 66 73 Parameter Format Description

SL F7.2 Solubility in water (µg/ml) DA F7.2 Air diffusion coefficient (cm2/sec) H F7.2 Henry’s Law constant (m3-atm/mol)

KOC F7.2 Organic carbon adsorption coefficient (µg/g)/( µg/ml) K F7.2 Soil partition coefficient (µg/g)/(µg/ml)

Line 3

MWT VAL KNH KBH KAH 38 45 52 59 66 73 Parameter Format Description

MWT F7.2 Molecular weight (g/mole) VAL F7.2 Valence of the compound KNH F7.2 Neutral hydrolysis rate constant (1/day) KBH F7.2 Base hydrolysis rate constant (l/mol/day) KAH F7.2 Acid hydrolysis rate constant (l/mol/day)



Line 4

KDEL KDES SK B MWTLIG DW 38 45 52 59 66 73 80 Parameter Format Description

KDEL F7.2 Liquid phase biodegradation rate (1/day) KDES F7.2 Solid phase biodegradation rate (1/day)

SK F7.2 Ligand stability (dissociation) constant B F7.2 Moles Ligand per mole compound

MWTLIG F7.2 Molecular weight of ligand (g/mol) DW F7.2 Water diffusion coefficient (cm2/sec)

Line 5

NCH 5 Parameter Format Description

NCH I5 End of chemical data file when NCH = 999



SESOIL Soil Data Parameters Line 1

NSO Soil Data Set Title 5 6 54


NSO I5 Index number for the soil data set TITLE A48 Soil data set title

Line 2

RS K1 C N OC 38 45 52 59 66 73 Parameter Format Description

RS F7.2 Bulk density (g/cm3) K1 F7.2 Intrinsic permeability (cm2) C F7.2 Soil pore disconnectedness index N F7.2 Effective porosity

OC F7.2 Organic carbon content (percent) Line 3

CEC FRN 38 45 52 Parameter Format Description

CEC F7.2 Cation exchange capacity (meg/100g) FRN F7.2 Freundlich exponent

Line 4

NSO 5


NSO I5 End of climate data file when NSO = 999



SESOIL Washload Data Parameters Line 1

NWS Washload Data Set Title IYRS 5 6 54 59

Parameter Format Description NWS I5 Index number for the washload data set

TITLE A48 Washload data set title IYRS I5 Number of years of washload in the data set

Line 2

AWR SLT SND CLY SLEN SLP 38 45 52 59 66 73 80

Parameter Format Description ARW F7.2 Washload area (cm2) SLT F7.2 Silt fraction SND F7.2 Sand fraction CLY F7.2 Clay fraction SLEN F7.2 Slope length (cm) SLP F7.2 Average land slope (cm/cm)

Skip line 3 Lines 4 to 7

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep 8 14 20 26 32 38 44 50 56 62 68 74 80

Line Parameter Format Description 4 KSOIL F6.2 Soil erodibility factor (tons/acre/english EI) 5 CFACT F6.2 Soil loss ratio 6 PFACT F6.2 Contouring factor (unitless) 7 NFACT F6.2 Manning’s coefficient (unitless)

Line 8

NWS 5

Parameter Format Description NWS I5 End of washload data file when NWS = 999



SESOIL Execution Data File Parameters

RUN OPTN CLIM SOIL CHEM WASH APPL YRS

5 6 10 15 20 25 30 35 40


RUN I5 Incremental number for the model run OPTN A4 Simulation option (the monthly option, “M”, is used for all cases) CLIM I5 The index number for the climate data file for the model run SOIL I5 The index number for the soil data file for the model run

CHEM I5 The index number for the chemical data file for the model run WASH I5 The index number for the washload data file for the model run APPL I5 The index number for the application data file for the model run YRS I5 The number of years to be simulated by the model run



SESOIL Application Data Parameters Line 1

NAP Application Data Set Title 5 6 54


NAP I5 Index number for the application data set TITLE A48 Application data set title

Line 2

ILYS IYRS AR L ISPILL 38 45 52 59 66 70

Parameter Format Description ILYS F7.2 Number of soil layers IYRS F7.2 Number of years of annual data in the application file AR F7.2 Application area (cm2) L F7.2 Latitude of site (degrees)

ISPILL I3 Spill index Line 3

D1 D2 D3 D4 NSUB1 NSUB2 NSUB3 NSUB4 38 45 52 59 66 70 73 76 79 Parameter Format Description

D1 F7.2 Upper soil layer thickness (cm) D2 F7.2 Second soil layer thickness (cm) D3 F7.2 Third soil layer thickness (cm) D4 F7.2 Lower soil layer thickness (cm)

NSUB1 I3 Number of sub-layers in upper soil layer NSUB2 I3 Number of sub-layers in second soil layer NSUB3 I3 Number of sub-layers in third soil layer NSUB4 I3 Number of sub-layers in lower soil layer



Line 4

PH1 PH2 PH3 PH4 38 45 52 59 66 Parameter Format Description

PH1 F7.2 pH of upper soil layer PH2 F7.2 pH of second soil layer PH3 F7.2 pH of third soil layer PH4 F7.2 pH of lower soil layer

Line 5

K11 K12 K13 K14 38 45 52 59 66 Parameter Format Description

K11 F7.2 Permeability of the upper soil layer (cm2) K12 F7.2 Permeability of second soil layer (cm2) K13 F7.2 Permeability of third soil layer (cm2) K14 F7.2 Permeability of lower soil layer (cm2)

Line 6

KDEL2 KDEL3 KDEL4 38 45 52 59 Parameter Format Description

KDEL2 F7.2 Ratio of KDEL (liquid phase biodegradation) layer 2 to 1 KDEL3 F7.2 Ratio of KDEL (liquid phase biodegradation) layer 3 to 1 KDEL4 F7.2 Ratio of KDEL (liquid phase biodegradation) layer 4 to 1

Line 7

KDES2 KDES3 KDES4 38 45 52 59 Parameter Format Description

KDES2 F7.2 Ratio of KDES (solid phase biodegradation) layer 2 to 1 KDES3 F7.2 Ratio of KDES (solid phase biodegradation) layer 3 to 1 KDES4 F7.2 Ratio of KDES (solid phase biodegradation) layer 4 to 1



Line 8

OC2 OC3 OC4 38 45 52 59 Parameter Format Description

OC2 F7.2 Ratio of OC (organic carbon content) layer 2 to 1 OC3 F7.2 Ratio of OC (organic carbon content) layer 3 to 1 OC4 F7.2 Ratio of OC (organic carbon content) layer 4 to 1

Line 9

CEC2 CEC3 CEC4 38 45 52 59 Parameter Format Description

CEC2 F7.2 Ratio of CEC (cation exchange capacity) layer 2 to 1 CEC3 F7.2 Ratio of CEC (cation exchange capacity) layer 3 to 1 CEC4 F7.2 Ratio of CEC (cation exchange capacity) layer 4 to 1

Line 10

FRN2 FRN3 FRN4 38 45 52 59 Parameter Format Description

FRN2 F7.2 Ratio of FRN (Freundlich exponent) layer 2 to 1 FRN3 F7.2 Ratio of FRN (Freundlich exponent) layer 3 to 1 FRN4 F7.2 Ratio of FRN (Freundlich exponent) layer 4 to 1

Line 11

ADS2 ADS3 ADS4 38 45 52 59 Parameter Format Description

ADS2 F7.2 Ratio of ADS (layer 2, organic carbon adsorption coefficient) to K (organic carbon adsorption coefficient from the chemical file, layer 1)





Lines 13 to 63

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep 8 14 20 26 32 38 44 50 56 62 68 74 80 Parameter Format Description

POLIN# F6.2 Monthly contaminant load (µg/cm2), for layer number # TRANS# F6.2 Monthly mass transformed by other process (µg/cm2), for layer

number # SINK# F6.2 Monthly mass removed by some other processes (µg/cm2), for

layer number # LIG# F6.2 Monthly input ligand mass (µg/cm2) , for layer number #

VOLF# F6.2 Index of volatilization, for layer number # ISMR F6.2 Index of contaminant transport in surface runoff ASL F6.2 Ratio of the contaminant concentration in precipitation to the

maximum water solubility Lines 65

SATCON HYDRA THICKS WIDTH BACKCA 8 14 20 26 32 38 Parameter Format Description SATCON F6.2 Saturated horizontal hydraulic conductivity (cm/sec). HYDRA F6.2 The slope of the potentiometric surface (ft/ft). THICKS F6.2 The thickness of the groundwater mixing zone (cm). WIDTH F6.2 The width of the contaminant release (cm).

BACKCA F6.2 Upgradient background groundwater contaminant concentration (µg/ml).

Lines 67 to 70

Sub- Layer

1

Sub- Layer

2

Sub- Layer

3

Sub- Layer

4

Sub- Layer

5

Sub- Layer

6

Sub- Layer

7

Sub- Layer

8

Sub- Layer

9

Sub- Layer

10 8 14 20 26 32 38 44 50 56 62 68 Parameter Format Description CONCIN1# F6.2 Initial layer 1 sub-layer contaminant load concentrations in

ppm. CONCIN2# F6.2 Initial layer 2 sub-layer contaminant load concentrations in

ppm.



CONCIN3# F6.2 Initial layer 3 sub-layer contaminant load concentrations in ppm.

CONCIN4# F6.2 Initial layer 4 sub-layer contaminant load concentrations in ppm.

Line 71

NAP 5


NAP I5 End of the application data file when NAP = 999

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�MILW_WI.CLM 1 MILWAUKEE WSO AP 1 **** YEAR 1 **** TA 10.50 2.94 -3.83 -7.39 -5.00 0.85 7.00 12.67 18.28 21.39 20.72 16.61 NN 0.46 0.60 0.62 0.55 0.53 0.50 0.47 0.41 0.36 0.30 0.34 0.41 S 0.73 0.75 0.76 0.72 0.72 0.72 0.69 0.69 0.70 0.72 0.76 0.76 A 0.17 0.21 0.30 0.33 0.30 0.29 0.19 0.17 0.17 0.17 0.17 0.17 REP 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 MPM 5.72 5.03 5.16 4.16 3.38 6.55 8.55 6.76 9.12 8.99 7.85 7.31 MTR 0.29 0.37 0.43 0.47 0.44 0.46 0.47 0.38 0.36 0.31 0.30 0.29 MN 4.02 4.50 4.38 3.48 3.00 5.05 6.31 5.88 6.05 5.40 5.62 4.55 MT 30.40 30.40 30.40 30.40 30.40 30.40 30.40 30.40 30.40 30.40 30.40 30.40 999 END OF FILE

BENZENE.CHM 1 Benzene - SL,DA,H,KOC,K 1780.00 0.0770.00555 31.00 0.0 - MWT,VAL,KNH,KBH,KAH 78.11 0.0 0.0 0.0 0.0 - KDEL,KDES,SK,B,MWTLIG,DW 0.0 0.0 0.0 0.0 0.09.80E-6 999 END OF FILE

SAND.SOI 1 Sand, Perm = 1.00E-3 cm/sec - RS,K1,C,N,OC 1.70 1.0E-8 4.00 0.25 0.50 - CEC,FRN 0.0 1.00 999 END OF FILE

SITEWASH.WSH 1 Site Sand Washload Data 1 ARW,SLT,SND,CLY,SLEN,SLP 100000. 0.15 0.75 0.101000.00 0.0100 **MONTHLY DATA** YR 1 KSOIL 0.10 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 CFACT 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 PFACT 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 NFACT 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 999 END OF FILE



DEFAULT.APL

1 SEVIEW Default Application Parameters -ILYS,IYRS,AR,L,ISPILL,ISUMRS,ICONC 4.00 2.001.00E+5 42.95 1 1 1 -D1,D2,D3,D4,NSUBL1 to NSUBL4 200.0 200.0 300.0 300.010 10 10 10 -PH1,PH2,PH3,PH4 7.00 7.00 7.00 7.00 -K11,K12,K13,K14 0.0 0.0 0.0 0.0 -KDEL MULTIPLIERS 1.00 1.00 1.00 -KDES MULTIPLIERS 1.00 1.00 1.00 -OC MULTIPLIERS 1.00 1.00 1.00 -CEC MULTIPLIERS 1.00 1.00 1.00 -FRN MULTIPLIERS 1.00 1.00 1.00 -ADS MULTIPLIERS 1.00 1.00 1.00 **** LAYER 1 ** YEAR 1 **** POLIN1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 ISRM 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ASL 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 **** LAYER 2 ** YEAR 1 **** POLIN2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF2 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 **** LAYER 3 ** YEAR 1 **** POLIN3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF3 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 **** LAYER 4 ** YEAR 1 **** POLIN4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF4 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 **** LAYER 1 ** YEAR 2 **** POLIN1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 ISRM 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ASL 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 **** LAYER 2 ** YEAR 2 **** POLIN2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF2 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 **** LAYER 3 ** YEAR 2 **** POLIN3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF3 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 **** LAYER 4 ** YEAR 2 **** POLIN4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRANS4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SINK4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 LIG4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 VOLF4 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 SUMMERS MODEL PARAMETERS FOLLOW (SATCON,HYDRA,THICKS,WIDTH,BACKCA) 1.0E-3 0.01 20.0 10.0 0.0 INITIAL CONTAMINANT CONCENTRATIONS FOLLOW CONCIN1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CONCIN20.9999 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CONCIN3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CONCIN4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 999 END OF FILE



(�3.��%�&3#(��-�� SERUN.BAT set fort22=C:\SEVIEW63\SITEWASH.WSH set fort2=C:\SEVIEW63\MILW_WI.CLM set fort3=C:\SEVIEW63\SAND.SOI set fort4=C:\SEVIEW63\BENZENE.CHM set fort20=C:\SEVIEW63\DEFAULT.APL sesoil<C:\SEVIEW63\EXEC020.EXC copy fort21 C:\SEVIEW63\RUN01.OUT del fort21 del serun.bat



(�3.�� , ��This section presents error or warning messages that are detected by the SESOIL code during operation. The messages are listed in alphabetical order and include a description of the message.

The “?????” indicate a number printed by SESOIL.

SESOIL Error Or Warning Message Description SESOIL Input File

ERROR, ILYS = ????? WHICH IS INCORRECT The number of layers given must be set to either 2, 3, or 4.

Application

ERROR, NSUBL1 = ????? WHICH IS INCORRECT The number of sub-layers in layer 1 must be at least 0 and less than or equal to 10.

Application


Application


Application

ERROR, NSUBLL = ????? WHICH IS INCORRECT The number of sub-layers in lowest layer must be at least 0 and less than or equal to 10.

Application

FATAL ERROR - AREA FOR WASHLOAD (ARW) MUST BE ON THE ORDER OF 10**4 OR MORE IS: ?????

The washload area is in error. Washload

FATAL ERROR - CLAY CONTENT (CLY) MUST BE BETWEEN 0 AND 1. IS: ?????

The clay fraction is in error. Washload

FATAL ERROR - CLOUD COVER (NN) MUST BE BETWEEN 0. AND 1.

The cloud cover must be a fraction.

Climate

FATAL ERROR - CLOUD COVER (NN) MUST BE BETWEEN 0. AND 1. IS: ?????

Cloud cover must be a fraction.

Annual

FATAL ERROR - LATITUDE (L) MUST BE LESS THAN 90 IS: ?????

Input for latitude of the site is incorrect.

Application

FATAL ERROR - LENGTH OF SEASON (MT) MUST BE LESS THAN 31

For monthly season simulation, length of season must be less than 31.

Climate

FATAL ERROR - SAND CONTENT (SND) MUST BE BETWEEN 0. AND 1. IS: ?????

Input for the sand fraction is in error.

Washload




FATAL ERROR - SILT CONTENT (SLT) MUST BE BETWEEN 0. AND 1. IS: ?????

Input for the silt fraction is in error.

Washload

FATAL ERROR - SOIL MOISTURE (SO) MUST BE BETWEEN 0. AND 100. IS: ?????

Input for soil moisture is incorrect.

Annual

FATAL ERROR - SOIL MOISTURE CALCULATED AS .LE. 0, CHECK FOR EVAPOTRANSPIRATION CLOSE TO OR EXCEEDING ANNUAL PRECIPITATION.

Check input data carefully. Climate, Soil, and

Application

FATAL ERROR - SOIL ORGANIC CARBON CONTENT (OC) MUST BE LESS THAN 100, IS: ?????

Input for organic carbon content is in error.

Soil

FATAL ERROR - SOIL POROSITY (N) MUST BE LESS THAN 1. IS: ????

Input for soil porosity is in error.

Soil

FATAL ERROR- HUMIDITY (S) MUST BE BETWEEN 0. AND 1. IS: ?????

Humidity must be a fraction. Annual

FATAL ERROR- HUMIDITY (S) MUST BE BETWEEN 0. AND 1. IS: ?????

Humidity must be a fraction. Climate

FATAL ERROR- LENGTH OF SEASON (MT) MUST BE LESS THAN 365 IS: ?????

The length of season must be 365 days or less.

Annual

SO OUT OF BOUNDS ***** CANNOT CONTINUE WITH THIS RUN

The SESOIL hydrologic cycle can not converge on soil moisture - check your input data carefully.

Climate, Soil, and

Application

WARNING - PROBLEM IN HYDRO CYCLE W EQUALS OR EXCEEDS EP, W SET TO EP

The velocity of the capillary rise (W), exceeds the evapotranspiration rate (EP). When this happens SESOIL sets W to 0.99 * EP. You should check the hydrologic results for reasonableness.

Climate, Soil, and

Application

WARNING - PROBLEM IN HYDRO CYCLE MN, MN LESS THAN 1., RAINFALL MAY NOT FOLLOW POISSON DISTRIBUTION (SEE WRR, P. 757, EQUATION (27)

The mean number of storm events for the month, is less than 1; check input (see Eagleson (1978), page 757 for details).

Climate

WARNING - PROBLEM IN HYDRO CYCLE: BETA GREATER THAN 0.5, RAINFALL MAY NOT FOLLOW POISSON DISTRIBUTION

Check input data cycle carefully for errors. Start with the duration of individual storms (MTR), the number of storm events per month (MN) and the length of the rainy season (MT) parameters first.

Climate




WARNING - PROBLEM IN HYDRO CYCLE: BETA/DELTA GREATER THAN 1., RAINFALL MAY NOT FOLLOW POISSON DISTRIBUTION (SEE WRR, P. 716, EQUATION (47))

Check the hydrologic cycle results for reasonableness. See Eagleson (1978), page 716, for details.

Climate

WARNING - PROBLEM IN HYDRO CYCLE: TIME BETWEEN STORMS LESS THAN 2 HRS. RAINFALL MAY NOT FOLLOW POISSON DISTRIBUTION (SEE WRR, P. 715, EQUATION (39))

Check input data carefully (see Eagleson (1978), page 715, for details)

Climate

WARNING - RAINFALL INPUT FLAG (ASL) IS USUALLY LESS THAN 1.

Check the values for the ratio of the contaminant concentration in precipitation to the maximum water solubility.

Application

WARNING - RAINFALL INPUT FLAG (ASL) IS USUALLY LESS THAN 1. IS: ?????

Check the values for the ratio of the contaminant concentration in precipitation to the maximum water solubility.

Annual

WARNING - RUNOFF FLAG (ISRA) IS USUALLY LESS THAN 1. IS: ?????

Input for surface runoff should be checked.

Annual

WARNING - RUNOFF FLAG (ISRM) IS USUALLY LESS THAN 1.

Input for surface runoff should be checked.

Application

WARNING - SOIL PERMEABILITY VARYS CONSIDERABLY AMONG LAYERS, SESOIL MAY NOT BE ACCURATE FOR SUCH AN INHOMOGENEOUS COLUMN

The SESOIL hydrologic cycle uses a single depth weighted average permeability value for the entire soil column. This message is printed whenever the average permeability is significantly different from the individual layer permeabilities.

Application

WARNING - SOLUBILITY ENTERED AS ZERO, SATURATION CHECKS MAY NOT WORK CORRECTLY

Check water solubility. Chemical

WARNING - VOLATILIZATION FLAG (VOLU) IS USUALLY LESS THAN 1. IS: ?????

The input for volatilization index should be checked.

Annual

WARNING - VOLATILIZATION FLAGS (VOL1, VOL2, VOL3, VOL4) ARE USUALLY LESS THAN OR EQUAL TO 1.

The inputs for volatilization index parameters (VOLF1, VOLF2, VOLF3 and VOLF4) should be checked.

Application

WARNING -SOIL PERMEABILITY (K1) IS USUALLY ON THE ORDER OF 10**-7 OR LESS, IS: ?????

Check the intrinsic permeability value.

Soil





Check the intrinsic permeability value for the upper soil layer.

Application


Check the intrinsic permeability value for the second soil layer.

Application


Check the intrinsic permeability value for the third soil layer.

Application


Check the intrinsic permeability value for the lower soil layer.

Application



("3.��%�!�� Bonazountas, M., J, Wagner, and B. Goodwin, Evaluation of Seasonal Soil/Groundwater Pollutant Pathways, EPA Contract No. 68-01-5949 (9), Arthur D. Little, Inc., Cambridge, Massachusetts, 1982. Bonazountas, M., and J. Wagner (Draft), SESOIL: A Seasonal Soil Compartment Model. Arthur D. Little, Inc., Cambridge, Massachusetts, prepared for the US. Environmental Protection Agency, Office of Toxic Substances, 1981, 1984. Bonazountas, M., D. H. Hetrick, P. T. Kostecki and E. J. Calabrese, SESOIL in Environmental Fate and Risk Modeling, 1997, Amherst Scientific Publishers, 661p. Brinkman, F. E. and J. M. Bellama (editors), Organometals and Organometalloids, Occurrence and Fate in the Environment, ACS Symposium Series 82, American Chemical Society, Washington, D.C., 1978. Brooks, R. H. and A. T. Corey, Properties of Porous Media Affecting Fluid Flow. Proc. ASCE Journal of the Irrigation and Drainage Division., No. IR 2, Paper 4855, 1966. Cowan, J. R., Transport of Water in the Soil-Plant-Atmosphere System. J. App. Ecology, Vol. 2, 1965. Donnigan and Dean, Environmental Exposures from Chemicals, Vol. 1. Edited by W. B. Neely and G. E. Blau, CRC Press, Boca Raton, Fla., p. 100, 1985. Eagleson, P. S., Climate, Soil, and Vegetation. Water Resources Research 14(5): 705-776, 1978. Eagleson, P. S. and T. E. Tellers, Ecological Optimality in Water-Limited Natural Soil-Vegetation Systems. 2. Tests and Applications. Water Resources Research 18 (2): 341-354, 1982. Fairbridge, R. W. and C. W. Finke, Jr. (editors), The Encyclopedia of Soil Science, Part 1. Stroudsburg, PA, Dowden, Hutchinson & Ross, Inc., 646 pp., 1979. Farmer, W. J., M. S. Yang, J, Letey, and W. F. Spencer, Hexachlorobenzene: Its Vapor Pressure and Vapor Phase Diffusion in Soil. Soil Sci. Soc. Am. J. 44, 676-680, 1980. Foster, G. R., L. J. Lane, J. D. Nowlin, J. M. Laflen, and R, A. Young, A Model to Estimate Sediment Yield from Field-Sized Areas: Development of Model. Purdue Journal No. 7781, 1980. Gardner, R. H., A Unified Approach to Sensitivity and Uncertainty Analysis. Proceedings of the Tenth IASTED International Symposium: Applied Simulation and Modeling, San Francisco, California, 1984.



Giesy. J. P. Jr., and J. J. Alberts, Trace Metal Speciation: The Interaction of Metals with Organic Constituents of Surface Waters. In Proc. of Workshop on The Effects of Trace Elements on Aquatic Ecosystems, Raleigh, North Carolina, March 23-24, B. J. Ward (editor) 1982. (published as EPRI EA3329, Feb 1984) Grayman, W. M. and P. S. Eagleson, Stream Flow Record Length for Modeling Catchment Dynamics. MIT Report No. 114, MIT Department of Civil Engineers, Cambridge, Massachusetts, 1969. Hamaker, J. W., Decomposition: Quantitative Aspects. In: Organic Chemicals in the Soil Environment, Vol. 1, C. A. I, Goring and J. W. Hamaker (editors), Marcel Dekker, New York, New York, 1972. Hetrick, D. M., J. T. Holdeman, and R, J. Luxmoore, AGTEHM: Documentation of Modifications to the Terrestrial Ecosystem Hydrology Model (TEHM) for Agricultural Applications. ORNUTM-7856, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 119 pp., 1982. Hetrick, D. M., Simulation of the Hydrologic Cycle for Watersheds. Paper presented at Ninth IASTED International Conference, Energy, Power, and Environmental Systems, San Francisco, California, 1984. Hetrick, D. M., C. C. Travis, P. S. Shirley, and E, L. Etnier, Model Predictions of Watershed Hydrologic Components: Comparison and Verification. Water Resources Bulletin, 22 (5), 803-810, 1986. Hetrick, D. M, and C. C. Travis, Model Predictions of Watershed Erosion Components, Water Resources Bulletin, 24 (2), 413-419, 1988. Hetrick, D. M., C. C. Travis, S. K. Leonard, and R. S. Kinerson, Qualitative Validation of Pollutant Transport Components of an Unsaturated Soil Zone Model (SESOIL). ORNL/TM-10672, Oak Ridge National Laboratory, Oak Ridge, TN, 42 pp., 1989. Hetrick, D. M., A. M. Jarabek, and C. C, Travis, Sensitivity Analysis for Physiologically Based Pharmackinetic Models. J. of Pharmackinetics and Biopharmaceutics, 19 (1) 1-20, 1991. Hetrick, D. M. and S. J. Scott, “The New SESOIL User’s Guide”, Wisconsin Department of Natural Resources, Madison, Wisconsin, 125 p., 1993 Holton, G, A., C. C. Travis, E. L. Etnier, F, R. O'Connell, D. M. Hetrick, and E. Dixon, Multi-Pathways Screening-Level Assessment of a Hazardous Waste Incineration Facility. ORNL/TM-8652, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 55 PPI 1984.



Holton, G. A., C. C. Travis, and E. L, Mnier, A Comparison of Human Exposure to PCB Emissions from Oceanic and Terrestrial Incineration. Hazardous Waste and Hazardous Materials, 2 (4), 453-471, 1985. Hornsby, A. G., P. S. C. Rao, W. B. Wheeler, P, Nkedi-Kizza, and R. L. Jones, Fate of Aldicarb in Florida Citrus Soils: Field and Laboratory Studies, In: Proc. of the NWACVU.S, EPA Conference on Characterization and Monitoring of the Vadose (Unsaturated) Zone, Las Vegas, NV, December 8-10, 0. M, Nielsen and M, Curl (editors), 936958, 1983. Jones, R. L., P. S. C. Rao, and A. G, Hornsby, Fate of Aldicarb in Florida Citrus Sail: 2. Model Evaluation. In: Proc. of the NWWA/U.S., EPA Conference on Characterization and Modeling of the Vadose (Unsaturated) Zone, Las Vegas, NV, December 8-10, D. M. Nielson and M. Curl (editors), 959-978, 1983. Jones, R. L., Field, laboratory, and Modeling Studies and the Degradation and Transport of Aldicarb Residues in Soil and Groundwater. Presented at ACS Symposium on Evaluation of Pesticides in Groundwater, Miami Beach, April 28 - May 1, 1985. Jones, R, L., Central California Studies on the Degradation and Movement of Aldicarb Residues, (Draft), 28 pp., 1986. Jury, W, A., W. J. Farmer, and W. F. Spencer, Behavior Assessment Model for Trace Organics in Soil: II. Chemical Classification and Parameter Sensitivity. J, Environ. Qual. 13(4), 567-572, 1984. Kincaid, C. T., J. R. Morery, S. B. Yabusaki, A. R. Felmy, and J. E. Rogers, Geohydrochemical Models for Solute Migration. Vol. 2: Preliminary Evaluation of Selected Computer Codes for Modeling Aqueous Solution and Solute Migration in Soils and Geologic Media. EA-3477, Electric Power Research Institute, Palo Alto, California, 1984. Knisel, W. G. (Editor), CREAMS: A Field-Scale Model for Chemicals, Runoff, and Erosion from Agricultural Management Systems. Conservation Research Report No. 26, U.S., Department of Agriculture, 1980. Knisel, W. G., G. R. Foster, and P. A. Leonard, CREAMS: A System for Evaluating Management Practices. Agricultural Management and Water Quality, by Schaller and Bailey, 1983. Ladwig, K. J. and Hensel, B. R., Groundwater Contamination Susceptibility Evaluation, SESOIL Modeling, Prepared for Wisconsin Department of Natural Resources, Madison, WI, 1993.



Lyman, W. J., W. F. Reehl, and D. H. Rosenblatt, Handbook of Chemical Property Estimation Methods, Environmental Behavior of Organic Compounds, McGraw-Hill Book Company, New York, New York, 1982. Melancon, S. M., J. E. Pollard, and S. C. Hern, Evaluation of SESOIL, PRZM, and PESTAN in a Laboratory Column Leaching Experiment. Environ. Toxicol. Chem, 5 (10), 865-878, 1986. Metzger, B. H. and P. S. Eagleson, The Effects of Annual Storage and Random Potential Evapotranspiration on the One-Dimensional Annual Water Balance. MIT Report No. 251. Massachusetts Institute of Technology, Department of Civil Engineering, Cambridge, Massachusetts 02139, 1980. Millington, R. J, and J. M. Quirk, Permeability of Porous Solids, Trans, Faraday Soc. 57, 1200-1207, 1961. Newell, C. J., McLeod R. K., Gonzales J. R., and Wilson J. T., BIOSCREEN Natural Attenuation Decision Support System, User’s Manual, Version 1.3, U.S. E.P.A. Cincinnati Ohio, 63pp, 1996. Odencrantz, J. E., J. M. Farr, and C. E. Robinson, Levine/Fricke, Inc., A Better Approach to Soil Cleanup Levels Determination. In: Transport Model Parameter Sensitivity for Soil Cleanup Level Determinations Using SESOIL and AT123D in the Context of the California Leaking Underground Fuel Tank Field Manual, Sixth Annual Conference on Hydrocarbon Contaminated Soils: Analysis, Fate, Environmental and Public Health, in Regulations, University of Massachusetts at Amherst, September, 1991. Odencrantz, J, E., J. M. Farr, and C. E. Robinson, Transport Model Parameter Sensitivity for Soil Cleanup Level Determinations Using SESOIL and AT123D in the Context of the California Leaking Underground Fuel Tank Field Manual. Journal of Soil Contamination, 1 (2), 159-182, 1992. O'Neill, R. V., R. H. Gardner, and J. H. Carney, Parameter Constraints in a Stream Ecosystem Model: Incorporation of A Priori Information in Monte Carlo Error Analysis. Ecol, Model. 16, 51-65, 1982. Patterson, M. R., T. J. Sworski, A. L. Sjoreen, M. G. Browman, C. C. Coutant, D. M. Hetrick, B. D. Murphy, and R. J. Raridon, A User's Manual for UTM-TOX, the Unified Transport Model. ORNL-6064, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 434 pp., 1984. Penman, H. L., Natural Evaporation from Open Water, Bare Soil, and Grass. Proc. Roy. Soc. (London), Series A, 193, 120-145, 1963. Philip, J. R., Theory of Infiltration. In Advances in Hydroscience, Vol. 5, edited by V. T. Chow, Academic Press, New York, New York, 1969.



Smith, C. N., G. W. Bailey, R. A. Leonard, and G. W. Langdale, Transport of Agricultural Chemicals from Small Upland Piedmont Watersheds. EPA-60013-78-056, IAG No, IAG-D6-0381, (Athens, GA: U.S. EPA and Watkinsville, GA: USDA), 364 pp., 1978. Sposito, G., Trace Metals in Contaminated Waters, Environ, Sci. Technol., Vol. 15, 396-403, 1981. Toy, T. J., A. J. Kuhaida, Jr., and B. E. Munson, The Prediction of Mean Monthly Soil Temperatures from Mean Monthly Air Temperature. Soil Sci., 126, 181-189, 1978. Travis, C. C., G. A. Holton, E. L. Etnier, C. Cook, F. R. O'Donnell, D. M. Hetrick, and E. Dixon, Assessment of Inhalation and Ingested Population Exposures from Incinerated Hazardous Wastes. Environment International, 12, 533-540, 1986. Tucker, W. A., C. Huang, and R. E. Dickinson, Environmental Fate and Transport. In: Benzene in Florida Groundwater, An Assessment of the Significance to Human Health. American Petroleum Institute, Washington, D. C., 79-122, 1986. Van den Honert, T. H., Water Transport in Plants as a Catenary Process. Discuss. Faraday Soc, 3, 1948. Wagner, J., M. Bonazountas, and M. Alsterberg, Potential Fate of Buried Halogenated Solvents via SESOIL. Arthur D. Little, Inc., Cambridge, Massachusetts, 52 pp., 1983. Walsh, P. J., L. W. Barnthouse, E. E. Calle, A. C. Cooper, E. D. Copenhaver, E. D. Dixon, C. S. Dudney, G. D. Griffin, D. M. Hetrick, G. A. Holton, T. D. Jones, B. D. Murphy, G. W. Suter, C. C. Travis, and M. Uziel, Health and Environmental Effects Document on Direct Coal Liquefaction - 1983. Prepared for Office of Health and Environmental Research and Office of Energy Research, Department of Energy, ORNL/TM-9287, Oak Ridge National Laboratory Oak Ridge, Tennessee, 130 pp., 1984. Watson, D. B. and S. M. Brown, Testing and Evaluation of the SESOIL Model, Anderson-Nichois and Co., Inc., Palo Alto, CA, 155 pp., 1985. Wischmeier, W. H. and D. D. Smith, Predicting Rainfall Erosion Losses from Cropland - A guide to Conservation Planning. Agricultural Handbook 537, U.S., Department of Agriculture, 58 pp., 1978. Yalin, Y. S., An Expression for Bedload Transportation, Journal of the Hydraulics Division. Proc. of the American Society of Civil Engineers, 89 (HY3), 221-250, 1963. Yeh, G. T., AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste Transport in the Aquifer System. ORNL-5602, Oak Ridge National Laboratory, Oak Ridge, TN 37831, 1981.



Appendix B

Introduction and Overview of the AT123D Model

Portions of this Appendix were originally presented as part of the “Analytical Transient 1-, 2-, and 3-Dimensional Simulation of

Waste Transport in the Aquifer System User’s Guide” prepared for the

Wisconsin Department of Natural Resources



#)3.�� (�)� *�

AT123D is an acronym for Analytical Transient 1-, 2-, and 3-Dimensional Simulation of Waste Transport in the Aquifer System. It is a generalized three-dimensional groundwater model developed by G. T. Yeh (1981) at Oak Ridge National Laboratory. Significant modifications were made by John Seymor (1982), Darryl Holman (1984) and Howard Trussell, (1986) of the University of Wisconsin-Madison. AT123D was further modified by Robert A. Schneiker (1997) at Environmental Software Consultants, Inc. The model was developed to estimate concentrations of contaminants transported, dispersed, degraded and sorbed in one-dimensional groundwater flow. The transport mechanisms simulated by AT123D include advection, dispersion, sorption, decay/biodegradation and heat losses to the atmosphere. Model results can be used to estimate how far a contaminant plume will migrate and can be compared to groundwater standards to evaluate risks at specific locations and times. Contaminant transport in AT123D can be modeled using one of two methods:

1. Contaminant transport without decay, and

2. Contaminant transport with biodegradation as a first-order decay process. The no biodegradation option is used to evaluate the transport and fate of non-degrading contaminants. Model results without biodegradation can also be compared to site conditions and/or modeling with biodegradation to evaluate the effects of remediation through natural attenuation (RNA).

When used with SEVIEW, AT123D produces monthly results and can simulate up to 1,000 years of contaminant transport. The AT123D program is written in FORTRAN. The results of a comparison between AT123D and analytical equations are presented in Section B3. A description of all AT123D input parameters including the data formats are presented in Section B4. An example AT123D input file is presented in Section B5. An example AT123D output file is presented in Section B6. A detailed description of the AT123D input parameters used in SEVIEW are presented in Section 8 of the SEVIEW User’s Guide.

There are a total of 450 AT123D run options. The run options are defined by the varying combinations of the three contaminant types, eight source configurations, three source release types, and four types of aquifer dimensions. There are 288 run options for the three-dimensional case, 72 for the two- dimensional case in the X-Y plane, 72 for the two- dimensional case in the X-Z plane, and 18 for the one- dimensional case in the longitudinal direction. A list of the run options is presented in Table 17 below.



Table 17 AT123D Run Options

Contaminant

Types Source

Configurations Releases

Type Aquifer

Dimensions Chemical Point source Instantaneous Infinite depth and

infinite width Heat Line source,

parallel to the x-, y-, or z-axis Finite Finite depth and

infinite width Radioactive Plane (area) source,

perpendicular to the x-, y-, or z-axis Continuous Infinite depth and

finite width Volume source Finite depth and

finite width

The AT123D model can simulate four types of groundwater boundary conditions. The boundary conditions modeled by AT123D are; specified head, specified flow, head-dependent flow and radiation boundaries. A description of these boundary conditions is presented in Section B2.2.

The initial load can now be established as either a concentration or a mass. As the equation governing contaminant transport and fate is linear, AT123D employs a superposition of simple, analytical (point source) solutions to generate solutions for various types of source releases and configurations, and aquifer dimensions. Line sources are simulated by superimposing an infinite number of point sources along a line. Area sources are simulated by superimposing an infinite number of line sources. Volume source loads are simulated by superimposing an infinite number of area sources. Superposition, for source configurations and boundary conditions and initial conditions, are represented by Green’s functions. Some of the solutions are in the form of an infinite series, whose terms must be evaluated and truncated at some finite point. A continuous source is evaluated by superimposing an infinite number of instantaneous source releases. The resulting spatial and temporal integrals of Green’s functions are evaluated numerically by Simpson’s rule. This means that AT123D performs numerous calculations to simulate contaminant transport and fate and borders on being a semi-analytical model.

B1.1 One- and Two-Dimensional Scenarios

AT123D can be used to model one-, two- and three-dimensional groundwater scenarios. To restrict AT123D to a one- or two-dimensional model the user must set the contaminant source width and/or depth to the width and/or depth of the aquifer. A description of this process is presented below.



B1.1.1 Two-Dimensional Scenarios

To restrict AT123D to a two-dimensional case the user must set the source width or depth to the width or depth of the aquifer. A two-dimensional model in the x-y plane is simulated by setting the starting coordinate of the source in the z-direction (RH1) to zero and the ending coordinate of the source in the z-direction (RH2) to the aquifer depth (DEPTH). A two-dimensional case in the x-z plane is simulated by setting the starting coordinate of the source in the y-direction (RB1) to zero and the ending coordinate of the source in the y-direction (RB2) to the aquifer width (WIDTH).

By setting the source coordinates along either the z- or y-axis to the aquifer depth or width, no variation in contaminant concentration in that direction can occur.

B1.1.2 One-Dimensional Scenarios

To limit AT123D to a one-dimensional case the user must set source width and depth to the width and depth of the aquifer. A one-dimensional model in the x-y plane is simulated by setting the starting and ending coordinates of the source in the y- and z-directions (RB1 and RH1) to zero. The user must also set the ending coordinate of the source in the y-direction (RB2) to the aquifer width (WIDTH) and the ending coordinate of the source in the z-direction (RH2) to the aquifer depth (DEPTH).

By setting the source distance along the y- and z-axis to the aquifer width and depth, no variation in concentration in those directions can occur.



#�3.��(�)� *�, ��*��

B2.1 Advection - Dispersion Equation

The AT123D model is based on the advection-dispersion equation which is used to determine the contaminant distribution in groundwater. Assuming incompressible flow the advection-dispersion equation is (Yeh, 1981):

( ) ( ) ( )∂∂

λ∂ ρ

∂λ ρ

n C

tn D C Cq M Kn C n C

C

tCe

e e eb s

b s= ∇ • ∇ − ∇ • +•

− − − +�

��

�

��

� (B1)

Where:

Parameter Description C Dissolved contaminant concentration Cs Adsorbed contaminant concentration

D Hydraulic dispersion coefficient tensor

K Chemical degradation rate M•. Contaminant source release rate ne Effective porosity �q Darcy’s velocity vector t Time ∇ Gradient (Del operator with respect to x, y, and z) λ Radioactive decay constant ρb Bulk density of the soil

By definition the ∇ is:

∇ =� � �i

xj

yk

z∂

∂∂

∂∂

∂+ +

�

��

�

��

The term on the left side of advection-dispersion equation represents the time rate of change of dissolved contaminant mass per unit volume of the aquifer. The first term on the right side of the equation represents the combined effects of hydraulic dispersion and molecular diffusion. The second term on the right side represents the advection of the contaminant. The third term represents the contaminant source load to the aquifer system. The fourth term on the right side of the equation accounts for the chemical and biological degradation of the contaminant, while the fifth term represents radioactive decay. The last two terms the equation, in parentheses, represent the effects of ion exchange and sorption.



The initial condition for Equation B1 is

( )C C x y z ti= =, , , 0 in R Where:

Parameter Description C Dissolved contaminant concentration Ci Initial contaminant concentration R A region with respect to x, y, and z (the region modeled) t Time x Longitudinal coordinate y Transfer coordinate z Vertical coordinate

This initial condition requires that the background concentration of the contaminant is known before the load is released into the aquifer.

B2.2 Boundary Conditions

AT123D can simulate four types of boundary conditions, depending on the physical situation being modeled. A description of these boundary conditions is presented in Table 18.

Table 18 AT123D Boundary Conditions

Boundary Condition Description Dirichlet Specified head. Neumann Specified flow. Cauchy or Mixed Type Head-dependent flow. Radiation Boundaries

B2.2.1 Dirichlet Boundary Conditions

The Dirichlet boundary condition defines a specific head boundary. Contaminant concentrations are specified along the boundary of the modeled region (S) or a portion (S1) as:



( )C C x y z t= 1 , , , in S1 Where:

Parameter Description C Dissolved contaminant concentration C1 Contaminant concentration on a portion of the boundary (S1) S The boundary of the region modeled R S1 A portion of the boundary of the region modeled (S) t Time x Longitudinal coordinate y Transfer coordinate z Vertical coordinate

The concentration (C1) is a given function of time and location on a portion of the boundary (S1).

B2.2.2 Neumann Boundary Conditions

The Neumann boundary condition defines a specific flow boundary. Where the contaminant concentration gradient is normal to the boundary of the region modeled (S) or a portion of the boundary (S2) of the boundary as:

( ) ( )− • ∇ • =n D C n q x y z te

�2 , , , on S2


C Dissolved contaminant concentration


∇ Gradient (Del operator with respect to x, y, and z) ne Effective porosity �n Unit vector normal to a portion of the boundary (S2) q2 Contaminant flux across the boundary at a given function of time and

location on a portion of the boundary (S2) S2 A portion of the boundary of the region modeled (S) t Time x Longitudinal coordinate y Transfer coordinate z Vertical coordinate



B2.2.3 Cauchy Boundary Conditions

The Cauchy boundary condition or mixed boundary condition is a head-dependent flow boundary. The Cauchy condition includes advective and dispersive transport through the boundary of the region modeled (S) or a portion of the boundary (S3) and may be written:

( ) ( )− • ∇ − • =n D C qC n q x y z te� �

3 , , , on S3


C Dissolved contaminant concentration


∇ Gradient (Del operator with respect to x, y, and z) ne Effective porosity �n Unit vector normal to a portion of the boundary (S2) �q Darcy’s velocity vector q3 Contaminant flux across the boundary at a given function of time and

location on S3 S3 A portion of the boundary of the region modeled (S) t Time x Longitudinal coordinate y Transfer coordinate z Vertical coordinate

B2.2.4 Radiation Boundary Conditions

AT123D includes a radiation boundary condition for simulations involving thermal conduction. The radiation boundary condition within AT123D is defined as:

n D C n n K Ce e e• ∇ • + =∗�0 on S4

Where:

Parameter Description C Initial temperature


∇ Gradient (Del operator with respect to x, y, and z) Ke

* Modified heat exchange coefficient

ne Effective porosity �n Unit vector normal to S4 S4 The soil-air interface portion of the boundary of the region modeled (S).



B2.3 Initial Conditions

To solve Equation B1, the initial and boundary conditions as defined above must be specified. Equation B1 is very difficult to solve analytically for typical groundwater situations. Assumptions must be made to simplify the aquifer geometry, boundary conditions, and the contaminant properties and load. These assumptions depend on the physical situation being modeled. Yeh (1981) made three assumptions to reduce Equation B1 to simplify the analytical solution.

1. The aquifer is assumed to be homogeneous and isotropic; thus, all of its properties (e.g., hydraulic conductivity, porosity, bulk density, aquifer thickness) are constant,

2. Groundwater flow is uniform along the positive x-axis (Figure B1), and

3. Sorption is in a state of instantaneous, linear, isothermal equilibrium so that S = KdC.

Dispersivities are an exception which are assumed constant throughout the aquifer (homogeneous), but may differ in the longitudinal (direction of flow), lateral (perpendicular to flow direction in the horizontal plane), and vertical (perpendicular to flow direction in the vertical plane) directions.

Figure B1: Sketch of source and aquifer dimensions. (after Yeh, 1981)

where

Parameter Description B Aquifer width H Aquifer depth L1 Starting coordinate of the source in the x-direction L2 Ending coordinate of the source in the x-direction B1 Starting coordinate of the source in the y-direction B2 Ending coordinate of the source in the y-direction H1 Starting coordinate of the source in the z-direction H2 Ending coordinate of the source in the z-direction



Using these assumptions, Equation B1 can be reduced to (Robertson, 1974):

( )∂∂

λC

tK C UC

KR

CM

n Rd e d

= ∇ • • ∇ − ∇ • − +�

��

�

�� +

•�

(B2)

Where:

Parameter Description C Dissolved contaminant concentration K Chemical degradation rate

K Retarded dispersion tensor

M•. Contaminant source release rate ne Effective porosity Rd Retardation factor t Time �

U Retarded seepage velocity vector ∇ Gradient (Del operator with respect to x, y, and z) λ Radioactive decay constant

The retardation factor RK

ndb d

e

= +1ρ

.

Where:

Parameter Description Kd Distribution coefficient ne Effective porosity ρb Bulk density of the soil Rd Retardation factor

The retarded dispersion tensor KDRd

=

Where:




Rd Retardation factor



The retarded seepage velocity �

�

Uqn

Re

d=�

��

�

�� / .

Where:

Parameter Description ne Effective porosity �q Darcy’s velocity vector Rd Retardation factor �

U Retarded seepage velocity vector

The solution of Equation B2, subject to the initial and boundary conditions can be written:

( ) ( )C x y z tM

n RGdR d GC K G nCdS d

Gqn R

dS dGqn R

dS de d

oRo

t

iR

dR

So

t

oe dSo

t

oe dSo

t

oo, , , =

•+ = − •∇ • − −�� τ τ τ τ τ0

1 2 3

12 3� (B3)

Where:

Parameter Description C Dissolved contaminant concentration Ci Initial contaminant concentration C1 Concentration on the boundary S1 G Green’s function


M•. Contaminant source release rate ne Effective porosity �n Unit vector normal to S2 q2 The contaminant flux across the boundary at a given function of time and

location on S2 q3 Contaminant flux across the boundary at a given function of time and

location on S3 R A region with respect to x, y, and z (region modeled) Ro A region with respect to ξ, η, and ζ S1 A portion of S S2 A portion of S S3 A portion of S So The boundary of the region modeled R t Time x Longitudinal coordinate y Transfer coordinate z Vertical coordinate ∇ Gradient (Del operator with respect to x, y, and z) τ Duration of the contaminant release

The “o” subscript refers to the performance of the operation with respect to ξ, η, and ζ rather than x, y, z.



Where G(x, y, z, t:ξ η ζ τ, , , ) is the Green’s function which satisfies the following:

( ) ( ) ( )limt G x y z→ = − − −τ δ ξ δ η δ ζ

G = 0 for t < τ G = 0 on S1

n D G ne o• ∇ • =�0 on S2

( )n D G qG ne o• ∇ + • =� �0 on S3

− • ∇ • + =∗D G n K G De

� on S4

and ( )− = ∇ • • ∇ + • ∇ − +�

��

�

��

∂∂ τ

λG

K G U GKR

Go od

� for t > τ

Where:

Parameter Description D Dispersion tension


δ Dirac Delta function G Green’s function K Chemical degradation rate Ke



ne Effective porosity �n Unit vector normal to S2 �q Darcy’s velocity vector Rd Retardation factor S1 Part of S S2 Part of S S3 Part of S S4 Part of S (soil-air interface portion of the boundary) t Time �

U Retarded seepage velocity vector x Longitudinal coordinate y Transverse coordinate z Vertical coordinate ∇ Gradient (Del operator with respect to x, y, and z) ∇o Del operator with respect to ξ, η, and ζ λ Radioactive decay constant τ Duration of the contaminant release ξ Longitudinal coordinate η Transverse coordinate ζ Vertical coordinate



Equation B3 represents the temporal and spatial distribution of the contaminant in terms of the source/sink term, M

• , the initial condition, Ci, and the boundary conditions, C1, q2, and q3. The only unknown is G, which is the Green’s function. Thus the initial-boundary in Equation l is reduced to a homogeneous problem Equation 4 for G.

For a discussion of Green’s functions, see De Wiest 1969. Green’s functions can be determined for many simple geometries, such as separable coordinate systems. For these simple geometries, Green’s function can be expressed as a product of three functions:

( ) ( ) ( ) ( )G x y z t G x t G y t G z t, , , : , , , , ; , , ; , , ; ,ξ η ζ τ ξ τ η τ ζ τ= 1 2 3

Parameter Description G Green’s function G1 Subgreen’s function G2 Subgreen’s function G3 Subgreen’s function t Time x Longitudinal coordinate y Transverse coordinate z Vertical coordinate τ Duration of the contaminant release ξ Longitudinal coordinate η Transverse coordinate ζ Vertical coordinate

The derivations for G1, G2 and G3 can be found in various references (see Yeh and Tsai, 1976, or Carslaw and Jaeger, 1959).

To solve Equation B3, it is assumed that no contaminant flows across the impervious boundaries and that all flow passes through open boundaries which are located at infinity. Thus C1 = 0, q2 = 0 and q3 = 0. Further, it is assumed that the initial (background) contaminant concentration, Ci = 0, Thus Equation B3 reduces to the following depending on the source duration: a) For continuous source or finite duration release and t < τ:

( ) ( )C x y z tM

n RF x y z t d

e dijk

o

t

, , , , , , ;=•

� τ τ



Where:

Parameter Description C Dissolved contaminant concentration

Fikj The integral of Green’s function over contaminant source space M•. Contaminant source release rate ne Effective porosity Rd Retardation factor t Time x Longitudinal coordinate y Transfer coordinate z Vertical coordinate τ Duration of the contaminant release

b) For finite duration source and t > τ:

( ) ( )C x y z tM

n RF x y z t d

e dijk

o

T

, , , , , , ;=•

� τ τ

c) For instantaneous source:

( ) ( )C x y z tM

n RF x y z t

e dijk, , , , , , ;= τ

Where:

Parameter Description M Total instantaneous contaminant mass released

Fijk is given by

F X Y Zijk i j k=

Where:

Parameter Description i l or 2 j l, 2, 3 or 4 k l, 2, 3 or 4 X1 A function defined below X2 A function defined below Y1 A function defined below Y2 A function defined below Y3 A function defined below Y4 A function defined below Z1 A function defined below Z2 A function defined below Z3 A function defined below Z4 A function defined below



The selection of which Xi, Yj, or Zk to use depends on the contaminant source and aquifer configurations. The ten Xi, Yj, or Zk functions are as follows: 1) For a point source in the x-direction:

( )( ) ( ){ }

( ) ( )XK t

x x U t

K tKR

txx

s

xx d1

21

4 4=

−−

− − −−

− +�

��

�

�� −

�

�

�

��π τ

ττ

λ τexp

2) For a line source in the x-direction:

( )( )

( )( )

( )X erfx L U t

K terf

x L U t

K t

KR

txx xx d

21 21

2 4 4=

− − −

−

�

�

��

�

�

��

−− − −

−

�

�

��

�

�

��

��

��

��

��• − +

�

��

�

�� −

�

�

��

ττ

ττ

λ τexp

3) For a finite width aquifer and point source in the y-direction:

( )YB B

i yB

i yB

iB

K ti

syy1

1

21 2= + ��

�� • �

��

�� • −�

��

�� −

�

�

��=

∞

� cos cos expπ π π τ

4) For a finite width aquifer and line source in the y-direction:

( )YB B

B Bi yB

Bi

i BB

i BB

iB

K ti

yy22 1

1

2 122= − + �

��

�� • �

��

�� − �

��

��

��

��

−��

�� −

�

�

��=

∞

� cos sin sin expπ

ππ π π τ

5) For a infinitely wide aquifer and point source in the y-direction:

( )( )

( )YK t

y yK t

yy

s

yy3

21

4 4=

−−

−−

�

�

��π τ τ

exp

6) For a infinitely wide aquifer and line source in the y-direction:

( ) ( )Y erf

y B

K terf

y B

K tyy yy

41 21

2 4 4=

−−

�

�

��

�

�

��

−−

−

�

�

��

�

�

��

�

�

�

��τ τ

7) For a finite depth aquifer and point source in the z-direction:

( ) ( ) ( )[ ]Z z z K ti i s i zzi

12

1

= • − −=

∞

�ψ ψ κ τexp

8) For a finite depth aquifer and line source in the z-direction:

( ) ( ) ( ) ( ) ( )[ ] ( )[ ]Z za

H HK

KH H K ti

i

ii i

e

zz ii i i zz

i2 2 1 2 1

2

1

=�

��

�

�� − − − ��

��

• − −∗

=

∞

�ψκ

κ κκ

κ κ κ τsin sin cos cos exp



9) For a infinitely deep aquifer and point source in the z-direction:

( )( )

( )( )

( ) ( ) ( )( )

( )ZK t

z zK t

z zK t

KK

KKK

tKK

z z erfcz z

K t

KK

K tzz

s

zz

s

zz

e

zzzz

e

zz

e

zzs

s

zz

e

zzzz3

2 2 21

4 4 4 4=

−−

−−

�

�

��

+ −+

−

�

�

��

��

��

��

��−

�

��

�

�� − +

�

��

�

�� +

�

�

�

��• +

−+ −

�

�

�

��

∗ ∗ ∗ ∗

π τ τ ττ

ττexp exp exp

10) For a infinitely deep aquifer and line source in the z-direction:

( ) ( ) ( ) ( )( )Z erf

z H

K terf

z H

K terf

z H

K terf

z H

K terf K

KK

tzz zz zz zz

zze

zz4

2 1 2 1

212 4 4 4 4

=+

−

�

�

�

��

−+

−

�

�

�

��

−−

−

�

�

�

��

+−

−

�

�

�

��

��

��

��

��−

�

��

�

�� −

�

�

�

��

∗

τ τ τ ττ

( )( )

( ) ( )( )

( )( ) ( )

•�

��

�

�� +

�

�

��•

+−

+�

��

�

�� −

�

�

�

��−

�

��

�

�� +

�

�

��•

+−

+�

��

�

�� −

�

�

�

��

��

��

��

��− +

−

�

�

�

��− −

−

�

�

�

��

��

��

��

�

∗ ∗ ∗ ∗

exp expKK

z H erfcz H

K t

KK

K tKK

z H erfcz H

K t

KK

K t erfz H

K terf

z H

K te

zz zz

e

zzzz

e

zz zz

e

zzzz

zz zz

22

11 2 1

4 4 4 4ττ

ττ

τ τ �

Where:

Parameter Description ai A coefficient defined below B Width of the aquifer L1 Starting coordinate of the source in the x-direction L2 Ending coordinate of the source in the x-direction B1 Starting coordinate of the source in the y-direction B2 Ending coordinate of the source in the y-direction H1 Starting coordinate of the source in the z-direction H2 Ending coordinate of the source in the z-direction K Chemical degradation rate Ke


Kxx X-component of the retarded dispersion tensor Kyy Y-component of the retarded dispersion tensor Kzz Z-component of the retarded dispersion tensor t Time U The magnitude of

�U the retarded seepage velocity vector

x Longitudinal coordinate xs X-coordinate of a point source y Transverse coordinate ys Y-coordinate of a point source z Vertical coordinate zs Z-coordinate of a point source λ Radioactive decay constant τ Duration of the contaminant release κi i-th eigenvalue defined below ψi i-th eigenfunction defined below erf Error function erfc Complimentary error function



The eigenfunction parameter ψi(z) is given by:

( ) ( ) ( )ψ κκ

κi i ie

zz iiz a z

KK

z= + ��

��

∗

cos sin

The eigenvalue parameter κi is given by:

( )tan κκie

zz i

HK

K=

∗

The parameter ai is given by:

a

HK

KK

K X

i

e

zz i

e

zz i

22

2

1

=

+�

��

�

�� +

�

��

�

��

��

��

��

��

∗ ∗

κ

Where:


H Depth of the aquifer

For non-heat flow cases, Ke∗ and κ π

i

iH

= − and aHi

2 2= .

For the three-dimensional cases, the applicable Xi, Yj and Zk are selected from the ten equations and multiplied together to obtain Fijk. For two-dimensional cases, the unused dimension’s coefficient is set equal to one (e.g., for a case involving the X-Z plane, Yj = 1). For one-dimensional cases, the two unused dimensions have their coefficients set equal to one (e.g., for a case involving only x, Yj = Zk = 1). For problems involving finite width aquifers, the Yj equations (using equations 3 and 4) converge very slowly for small values of Kyy (t-τ)/B2 (Yeh, 1981). This situation occurs when the aquifer is very wide and the contaminant concentrations during the initial time steps (t is small) are being calculated. For this case the program uses alternate Yj equations calculated by the method of images, to provide more rapid convergence. These equations are:

( )( ){ }

( )( ) ( ){ }

( )( ) ( ){ }

( )( ){ }

( )YK t

y y nB

K t

y y n B

K t

y y n B

K t

y y nB

K tyy

s

yy

s

yynn

s

yyn

s

yyn1

2 2

00

2

0

2

0

1

4

2

4

2 1

4

2 1

4

2

4=

−−

− +−

�

�

�

��+ −

− − −−

�

�

�

��+ −

− + −−

�

�

�

��+ −

− +−

�

�

�

��

��

��

�

��

��=

∞

=

∞

=

∞

=

∞

�� π τ τ τ τ τexp exp exp exp

and

( )( )

( )( )

( ) ( )( )

( ) ( )( )

( ) ( )( )

( ) ( )( )

( )( )

Y erfy B nB

K terf

y B nB

K terf

y B n B

K terf

y B n B

K terf

y B n B

K terf

y B n B

K terf

y B nB

K terf

yy yy yy yy yy yy yy

21 2 1 2 2 1 21

2

2

4

2

4

2 1

4

2 1

4

2 1

4

2 1

4

2

4=

− −

−

�

�

�

��−

− −

−

�

�

�

��+

− + −

−

�

�

�

��−

− + −

−

�

�

�

��+

+ + −

−

�

�

�

��−

+ + −

−

�

�

�

��+

+ −

−

�

�

�

��−

τ τ τ τ τ τ τ( )

( )y B nB

K tyyn

+ −

−

�

�

�

��

��

��

�

��

��=

∞

� 1

0

2

4 τ



Where:

Parameter Description B Width of the aquifer B1 Starting coordinate of the source in the y-direction B2 Ending coordinate of the source in the y-direction Kyy Y-component of the retarded dispersion tensor t Time Y Transverse coordinate Ys Y-coordinate of a point source τ Duration of the contaminant release

The integral of Green’s function, Fijk can have 32 different equations using the ten equations for Xi, Yj and Zk (32 is the number of permutations of 2 Xi, 4 Yj and 4 Zk). Substituting these 32 equations into the three equations for the source release (continuous or finite duration release with t < τ, finite duration release with t > τ, and instantaneous release), 96 equations are obtained. As these equations are applicable to 3 types of contaminants (chemical, thermal or radioactive), there are 288 options for the three-dimensional case. Similarly, there are 144 options for the two-dimensional case, 72 involving the x-y plane and 72 involving the x-z plane [2 Xi times 4 Yj (or 4 Zk) times 3 source release types times 3 contaminant types]. For the one- dimensional case, in the x-direction, there are 18 options (2 Xi times 3 source release types times 3 contaminant types). Thus, there are a total of 450 run options in the AT123D model. AT123D determines the concentration at (x, y, z, t) from a continuous or finite duration release by superimposing the contributions from instantaneous contaminant releases at τ (where 0 < τ < t). To carry out the integration necessary for computing concentrations resulting from continuous or finite duration source releases, AT123D uses Simpson’s rule to numerically calculate the time integral. A source release rate that varies through time is modeled as a sequence of finite duration releases of varying load.



# 3.��!� ��!�(�)� *�

This section presents the results of a verification of the AT123D using analytical equations. A total of four verification scenarios were performed (Yeh et al., 1987). Three of the solutions were for infinite aquifers with instantaneous source releases under uniform flow (point source with three dimensional mixing, infinite line source lying along the z-axis, and a line source lying along the y-axis with a finite width aquifer). The fourth solution was for a continuous point source with three-dimensional mixing.

Identical concentrations were determined using AT123D and the analytical equations, although some concentrations differ in the final decimal place due to different rounding techniques. Identical results are anticipated as AT123D uses analytical equations to determine the predicted groundwater concentrations.

B3.1 Solution for an Instantaneous Point Source

The following equation was used to determine groundwater contaminant concentrations for an instantaneous point source with uniform groundwater flow parallel to the x-axis. The source is at the origin (x, y and z equal 0), and in an infinite aquifer (semi-infinite in z-direction):

( )( )

( )C x y z t

M

n t D D D

x vt

D tyD t

zD t

e x y zx y x

, , , exp= −−

− −

��

��

�

��

��4 4 4 432

22 2

π

Where:

Parameter Description Units M Mass of contaminant introduced Grams Dx Dispersion coefficients in x direction Meters Dy Dispersion coefficients in y direction Meters Dz Dispersion coefficients in z direction Meters v Average linear velocity Meters/hour ne Aquifer porosity Fraction t Time after injection Hours

From Freeze, Cherry, 1979.

Data for the solution

Mass contaminant load is 25,000 grams. Porosity is 0.25. Dispersivities (α) are 5 meters, 0.5 meters, and 0.5 meters in the x, y, z directions, respectively. Hydraulic conductivity is 3.6 meters/hour with a gradient of 0.02 meters/meter.

Results

Identical groundwater contaminant concentrations were determined using the analytical equation and the AT123D model. A summary of the results is presented in Table 19.



Table 19 Analytical Solution for an Instantaneous Point Source

Time (hours)

x (meters)

y (meters)

z (meters)

Analytical Concentration

(mg/l)

AT123D Concentration

(mg/l) 24 10 0 0 206.25 206.25

11 0 0 195.82 195.82 12 0 0 183.24 183.24 13 0 0 169.01 169.01 14 0 0 153.65 153.65 15 0 0 137.67 137.67 16 0 0 121.59 121.59 17 0 0 105.84 105.84 18 0 0 90.81 90.81 19 0 0 76.79 76.79 20 0 0 64.00 64.00

24 10 0 0 206.25 206.25 10 1 0 191.86 191.86 10 2 0 154.86 154.86 10 3 0 107.56 107.56 10 4 0 64.82 64.82 10 5 0 33.81 33.81 10 6 0 15.26 15.26 10 7 0 5.96 5.96 10 8 0 2.01 2.01 10 9 0 0.59 0.59

24 10 0 0 206.25 206.25 10 0 1 191.86 191.86 10 0 2 154.86 154.86 10 0 3 107.56 107.56 10 0 4 64.82 64.82 10 0 5 33.81 33.81 10 0 6 15.26 15.26 10 0 7 5.96 5.96 10 0 8 2.01 2.01 10 0 9 0.59 0.59

24 10 0 0 206.25 206.25 26 10 0 0 187.89 187.89 28 10 0 0 171.33 171.33 30 10 0 0 156.44 156.44 32 10 0 0 143.05 143.05 34 10 0 0 131.03 131.03 36 10 0 0 120.21 120.21 38 10 0 0 110.47 110.47 40 10 0 0 101.68 101.68 42 10 0 0 93.74 93.74 44 10 0 0 86.55 86.55



B3.2 Solution for an Instantaneous Semi-Infinite Line Source

The following equation was used to determine groundwater concentrations for a semi-infinite line source parallel to the z-axis. The source length was established such that the z-dimension is neglected (0, ∞). The source is at x and y equal 0 and the source release starts at t equal to 0:

( ) ( )C x y z t

Mn t D D

x vt

D tyD te x y x y

, , , exp= −−

−

��

��

�

��

��4 4 4

22

π

From Carslaw, Jaeger, 1959, p 258.

Where:

Parameter Description Units M Mass of contaminant load per unit length of line source. Grams/meter Dx Dispersion coefficients in x direction Meters Dy Dispersion coefficients in y direction Meters Dz Dispersion coefficients in z direction Meters

v Average linear velocity Meters/hour

ne Aquifer porosity Fraction t Time after injection Hours

Within AT123D this scenario is simulated using a finite depth solution with a line source extending over the entire depth of aquifer.


Hydraulic conductivity and gradient are 1 meters/hour and 0.02 respectively. Porosity is 0.25. Longitudinal and transverse dispersivities are 5 meters and 0.5 meters, respectively. Contaminant mass load is 1000 grams/meter. In AT123D the line source length was set to 25 meters. This length is arbitrary as long as it results in 1000 grams/meter of mass released from the line source. Results

Identical groundwater contaminant concentrations were determined using the analytical equation and the AT123D model. However, some concentrations varied slightly due to different numerical rounding techniques. A summary of the results is presented in Table 20.



Table 20 Analytical Solution for an Instantaneous Semi-Infinite Line Source

Time

(hours) x

(meters) y

(meters) Analytical

Concentration (mg/l)


(mg/l) 96 10 0 25.31 25.31

11 0 24.40 24.40

12 0 23.21 23.21

13 0 21.80 21.80

14 0 20.21 20.21

15 0 18.49 18.49

16 0 16.70 16.70

17 0 14.89 14.89

18 0 13.10 13.10

19 0 11.38 11.38

20 0 9.76 9.76

96 10 0 25.31 25.31

10 0 23.72 23.72

10 0 19.51 19.51

10 0 14.09 14.09

10 0 8.93 8.93

10 0 4.97 4.97

10 0 2.43 2.43

10 0 1.04 1.04

10 0 0.39 0.39

10 0 0.13 0.13

72 10 0 29.90 29.90

78 10 0 28.81 28.81

84 10 0 27.65 27.65

90 10 0 26.48 26.48

96 10 0 25.31 25.31

102 10 0 24.16 24.17

108 10 0 23.05 23.05

114 10 0 21.98 21.98

120 10 0 20.95 20.95

126 10 0 19.97 19.97

132 10 0 19.04 19.04



B3.3 Solution for Instantaneous Line Source in a Finite Width Aquifer

The following equation was used to determine the groundwater concentrations for a line source along the y-axis at x and z equal to 0 in a semi-infinite depth aquifer. Groundwater mixing is in three-dimensions. This formula uses Green’s functions and the method of images.

( )C x y z tMn

FMn

X Y Ze

ijke

, , , = = • •

Where:

Parameter Description Units M Mass of contaminant load introduced/unit length of line source Grams

/meter X Instantaneous point source at x = 0 (infinite medium)

( )= −

−

��

��

�

��

��

14 4

2

πD t

x vt

D tx x

exp

Y Instantaneous line source in a finite aquifer

( ) ( ) ( ) ( )= − +��

�� − − +�

��

��

�

�

��+ + +�

��

�� − + +�

��

��

�

�

��+

− − +�

��

�

�� −

− − +�

��

�

��

�

�

��+

+ − +�

��

�

�� −

− − +�

��

�

��

�

�

��

��

��

��

��=

∞12

2 2 2 2 2 1 2 1 2 1 2 11 2 2 1 1 2 2 1

0

erfy B nB

Aerf

y B nBA

erfy B nB

Aerf

y B nBA

erfy B n B

Aerf

y B n BA

erfy B n B

Aerf

y B n BAn

�

Z Instantaneous point source at z = 0 (semi-infinite depth)

= − ��

��

24 4

2

πD tzD tz z

exp

A 4D ty

Carslaw, Jaeger, 1959, p 358 and J. A. Hoopes for Yeh, (from Yeh et al., 1987)


Hydraulic conductivity and gradient, porosity, and mass/unit length of the line source are 1.0 m/hr and 0.02, 25%, and 1000 grams/meter respectively. Dispersivities are 5 m, 0.5m and 0.5 m in the x, y, and z directions respectively. The aquifer width, B, is 100 m. End points of the line source are B1 = -12.5 m and B2 = 12.5 m. Results




Table 21 Analytical Solution for an Instantaneous Line Source in a Finite Width Aquifer

Time

(hours) x

(meters) y

(meters) z

(meters) Analytical

Concentration (mg/l)


(mg/l) 96 10 0 0 101.24 101.24

11 0 0 97.59 97.59 12 0 0 92.86 92.86 13 0 0 87.21 87.21 14 0 0 80.84 80.85 15 0 0 73.97 73.98 16 0 0 66.81 66.81 17 0 0 59.56 59.57 18 0 0 52.41 52.42 19 0 0 45.53 45.53 20 0 0 39.03 39.03

96 10 0 0 101.24 101.24 10 3 0 101.21 101.21 10 6 0 100.28 100.28 10 9 0 90.78 90.79 10 12 0 57.87 57.87 10 15 0 18.58 18.58 10 18 0 2.39 2.39 10 21 0 0.11 0.11 10 24 0 0.00 0.00 10 27 0 0.00 0.00

96 10 0 0 101.24 101.24 10 0 1 94.86 94.86 10 0 2 78.03 78.03 10 0 3 56.35 56.35 10 0 4 35.73 35.73 10 0 5 19.88 19.88 10 0 6 9.72 9.72 10 0 7 4.17 4.17 10 0 8 1.57 1.57 10 0 9 0.52 0.52 72 10 0 0 119.60 119.60 78 10 0 0 115.23 115.24 84 10 0 0 110.61 110.62 90 10 0 0 105.92 105.92 96 10 0 0 101.24 101.24

102 10 0 0 96.66 96.65 108 10 0 0 92.21 92.20 114 10 0 0 87.92 87.92 120 10 0 0 83.81 83.80 126 10 0 0 79.88 79.87 132 10 0 0 76.13 76.13



B3.4 Solution for a Continuous Point Source in a Finite Depth Aquifer

The following equation was used to determine groundwater concentrations for a continuous point source at x, y and z equal to 0. The release was initiated at t equal to 0. The aquifer is infinite in x- and y-dimensions, and semi-infinite in z-dimension. Groundwater flow is uniform and is parallel to x-axis.

( )( )

C x y z t

MvD

R x

n R D Derfc

R vtD t

vRD

erfcR vt

D tx

e y z x x x

, , ,exp

exp= •− −�

�

�� −�

�

��

+�

��

�

�� • +�

��

�

��

��

��

��

��

•

22

8 4 4π

From Yeh et al., 1987. Where

Parameter Description Units M•

Contaminant mass flow rate Grams/hour

R xDD

yDD

zx

y

x

z

2 2 2

12

+ +�

��

�

��

Data for the solution Contaminant mass flow rate is 25 g/hr. Porosity is 25%. Dispersivities are 5 m, 0.5 m and 0.5 m in the x, y, and z directions respectively. Hydraulic conductivity is 1.0 m/hr, while the gradient is 0.02. Results




Table 22 Analytical Solution for a Continuous Point Source

Time (hours)

x (meters)

y (meters)

z (meters)

Analytical Concentration

(mg/l)


(mg/l) 96 10 0 0 22.16 22.16

120 10 0 0 25.93 25.93 144 10 0 0 28.74 28.74 168 10 0 0 30.89 30.89 192 10 0 0 32.54 32.54 216 10 0 0 33.84 33.84 240 10 0 0 34.87 34.87 264 10 0 0 35.69 35.69 288 10 0 0 36.36 36.36 312 10 0 0 36.91 36.91 336 10 0 0 37.36 37.36 240 5 0 0 76.15 76.16

6 0 0 62.61 62.61 7 0 0 52.84 52.84 8 0 0 45.43 45.43 9 0 0 39.60 39.60 10 0 0 34.87 34.87 11 0 0 30.93 30.93 12 0 0 27.60 27.60 13 0 0 24.74 24.74 14 0 0 22.24 22.24

240 10 0 0 34.87 34.87 10 1 0 31.30 31.30 10 2 0 23.42 23.42 10 3 0 15.58 15.59 10 4 0 9.68 9.68 10 5 0 5.75 5.75 10 6 0 3.29 3.29 10 7 0 1.83 1.83 10 8 0 0.98 0.98 10 9 0 0.51 0.51

240 10 0 0 34.87 34.87 10 0 1 31.30 31.30 10 0 2 23.42 23.42 10 0 3 15.58 15.59 10 0 4 9.68 9.68 10 0 5 5.75 5.75 10 0 6 3.29 3.29 10 0 7 1.83 1.83 10 0 8 0.98 0.98 10 0 9 0.51 0.51



#�3.��(�)� *�*��

This appendix provides a description of the AT123D input parameters. AT123D uses ASCII text files to store the information used in the model scenarios. These files must be formatted so that the AT123D program correctly read the data. A description of the FORTRAN read format is also provided.

Title Line 1

TITLE 80


TITLE A80 The title for the model scenario.

Basic Integer Parameters Line 2

NX NY NZ NROOT NBGTI NEDTI NPRINT INSTAN 5 10 15 20 25 30 35 40

IBUG NSOURS INTER ICASE IDEP IWID ROC RKOC 45 50 55 60 65 66 73 80 Parameter Format Description

NX I5 Number of points in the x-direction (parallel to flow) where the concentration is desired. (Maximum = 15).

NY I5 Number of points in the y-direction (perpendicular to flow in horizontal plane) where the concentration is desired. (Maximum = 10)

NZ I5 Number of points in the z-direction (perpendicular to flow in the vertical plane) where the concentration is desired. (Maximum = 10)

An array of points for solution (NX, NY, NZ) is formed by these first three values. In other words, for each point in the x-direction, a solution will be generated for all possible x, y, z combinations using that x (e.g., if NX = NY = NZ = 3, then final concentrations will be calculated for 27 points.)



Parameter Format Description NROOT I5 Number of eigenvalues required for series evaluation. The number

of eigenvalues may not exceed 1000. NROOT represents the maximum number of terms that will be calculated for a series solution before truncation occurs. Start with 500 and increase it to a 1000 if a warning message is printed out with the solution.

NBGTI I5 Starting time step where the solution is desired.

As AT123D counting loops start with 1 not 0, a 1 must be added to the values for NBGTI and NEDTI. For example, if you wanted a solution from year 10 to year 20, NBGTI should be set to 121 months and NEDTI should be set to 241 months.

NEDTI I5 Ending time step where the solution is desired.

NPRINT I5 Print out time step in terms of DT. INSTAN I5 Integer parameter indicating if the contaminant release is

instantaneous or continuous; = 0 for instantaneous release (slug), = 1 for continuous release.

NSOURS I5 Integer parameter indicating if the source release is constant or changing over time; = 0 for constant source, > 0 for varying sources.

NSOURS must be set to the total number of contaminant releases.

INTER I5 Integer parameter indicating if intermittent solutions between NBGTI and NEDTI are to be printed: = 0 for No, = 1 for Yes.

ICASE I5 Integer parameter indicating the type of contaminant to be simulated: 1 for thermal, 2 for chemical and 3 for radio active.

IWID I5 Integer parameter indicating if the aquifer is infinite or not in the y-direction; = 0 for Yes, = 1 for No.

IDEP I5 Integer parameter indicating if the aquifer is infinitely deep or not; = 0 for Yes, = 1 for No.

IBUG I1 Integer parameter indicating if the diagnostic check is desired or not; no = 0, 1 for yes.

ROC F7.2 Organic carbon content (percent) RKOC F7.2 Organic carbon adsorption coefficient (µg/g)/( µg/ml)

IBUG is typically set to 0.



Aquifer Size and Source Size Line 3 DEPTH WIDTH RL1 RL2 RB1 RB2 RH1 RH2 10 20 30 40 50 60 70 80 Parameter Format Description

DEPTH F10.0 Aquifer depth (meters). WIDTH F10.0 Aquifer width (meters).

RL1 F10.0 Beginning coordinate of the source load in the x-direction (meters). RL2 F10.0 Ending coordinate of the source load in the x-direction (meters).

RB1 F10.0 Beginning coordinate of the source load in the y direction (meters). RB2 F10.0 Ending coordinate of the source load in the y direction (meters). RH1 F10.0 Beginning coordinate of the source load in the z-direction (meters).

RH2 F10.0 Ending coordinate of the source load in the z direction (meters).

The F 10.0 format can read either exponential or real numeric formats.

Soil and Waste Properties Line 4

POR HCOND HGRAD AELONG ATRANV AVERTI AKD CONC 10 20 30 40 50 60 70 80 Parameter Format Description

POR F10.0 Porosity of the soil (decimal, dimensionless). HCOND F10.0 Hydraulic conductivity (meters/hour). HGRAD F10.0 Hydraulic gradient (meters/meters).

AELONG F10.0 Longitudinal dispersivity (meters). ATRANV F10.0 Transverse dispersivity (meters). AVERTI F10.0 Vertical dispersivity (meters).

AKD F10.0 Distribution coefficient, Kd (m3/kg). CONC F10.0 Initial contaminant concentration, (mg/L).



Additional Soil and Waste Properties and Some Real Number Parameters Line 5 AMTAU RAMADA RHOB RHOW ACCU DT TDISP Q

10 20 30 40 50 60 70 80 Parameter Format Description AMTAU F10.0 Molecular diffusion coefficient times tortuosity (m2/hr).

RAMADA F10.0 Decay constant (per hour). RHOB F10.0 Bulk density of the soil (kg/m3). RHOW F10.0 Density of water (kg/m3).

ACCU F10.0 Error tolerance if steady-state solution is desired (Note: 0.001 is a reasonable value for ACCU).

DT F10.0 Time step size for calculating the solution (hours). TDISP F10.0 Total length of time over which the contaminant is to be released

into the aquifer (hours)

Q F10.0 Constant rate of contaminant release in kg/hr, kcal/hr, or CI/hr, or the total instantaneous release in kcal, kg, or CI.

X-Axis Coordinates Line 6 The number of lines in the file depends on the number of points in the x-direction (NX). There may be up to eight x-coordinate values on a line. XDIM(1) XDIM(2) XDIM(3) XDIM(4) XDIM(5) XDIM(6) XDIM(7) XDIM(8) 10 20 30 40 50 60 70 80 Parameter Format Description XDIM(I) F10.0 X-coordinate of the I-th point in the x-direction (direction of

flow), where a concentration will be determined (meters).



Y-Axis Coordinates The number of lines in the file depends on the number of points in the y-direction (NY). There may be up to eight y-coordinate values on a line. YDIM(1) YDIM(2) YDIM(3) YDIM(4) YDIM(5) YDIM(6) YDIM(7) YDIM(8) 10 20 30 40 50 60 70 80 Parameter Format Description YDIM(I) F10.0 Y-coordinate of the I-th point in the y-direction (horizontally

perpendicular to flow), where a concentration will be determined (meters).

Z-Axis Coordinate The number of lines in the file depends on the number of points in the z-direction (NZ). There may be up to eight z-coordinate values on a line. ZDIM(1) ZDIM(2) ZDIM(3) ZDIM(4) ZDIM(5) ZDIM(6) ZDIM(7) ZDIM(8) 10 20 30 40 50 60 70 80 Parameter Format Description ZDIM(I) F10.0 Z-coordinate of the I-th point in the z-direction (vertically

perpendicular to flow), where a concentration will be determined (meters).

Variable Source Release Time Steps Used to define the number of varying contaminant loads (not used in constant release scenarios). The number of lines depends on the total number of contaminant loads (NSOURS). There may be up to 16 time step values on a line. ITS(1) ITS(2) ITS(3) . . . . ITS(NSOURS)

5 10 15 Parameter Format Description

ITS(I) I5 Integer number for the I-th time step number (in terms of DT) at which the release rate changes. Begin with 1 (remember AT123D loops start at 1, not 0), and continue with an integer in each field of 5 spaces, There should be a total of NSOURS ITS(I) entries.



Variable Source Release Rates

Used to specify the varying contaminant release loads (not used in constant release scenarios). The number of lines depends on the total number of contaminant loads (NSOURS). There may be up to six contaminant load values on a line. QSA(1) QSA(2) QSA(3) . . . . QSA(NSOURS) 12 24 36 Parameter Format Description

QSA(I) F12.0 Waste release rate at time step corresponding to the variable source release time step [ITS(I)]

Use same units as the constant release rate (Q) in kg/hr, kcal/hr, or CI/hr.

There must be as many variable source release rates [QSA(I)'s] as variable source release time steps [ITS(I)'s] and NSOURS entries.



#�3.��(�)� *��4��*��-��RUN01.ATI Benzene in Sand 7 5 2500 25 2411 1 2401 2 0 005.00E-13.10E+1 0.0 0.0-1.581E+00 1.581E+00-1.581E+00 1.581E+00 0.0 0.0 2.500E-01 3.600E-02 0.003 2.16 0.2 0.02 1.550E-04 .0000E+00 3.528E-06 0.000E+00 1.700E+03 .1000E+04 0.010.7300E+03 1.752E+050.7300E+03 0.0 5.0 10.0 15.0 20.0 25.0 30.0 -10.0 -5.0 0.0 5.0 10.0 0.0 1.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.061E-09 3.764E-08 4.469E-08 4.058E-08 2.573E-08 3.576E-08 3.971E-08 3.021E-08 3.831E-08 3.961E-08 3.305E-08 3.063E-08 2.465E-08 2.784E-08 3.169E-08 2.839E-08 1.791E-08 2.480E-08 2.746E-08 2.086E-08 2.639E-08 2.726E-08 2.271E-08 2.102E-08 1.691E-08 1.909E-08 2.171E-08 1.945E-08 1.227E-08 1.698E-08 1.879E-08 1.427E-08 1.805E-08 1.863E-08 1.553E-08 1.436E-08 1.156E-08 1.304E-08 1.484E-08 1.329E-08 8.386E-09 1.160E-08 1.284E-08 9.750E-09 1.233E-08 1.273E-08 1.061E-08 9.821E-09 7.901E-09 8.916E-09 1.014E-08 9.082E-09 5.730E-09 7.928E-09 8.775E-09 6.661E-09 8.428E-09 8.701E-09 7.250E-09 6.710E-09 5.398E-09 6.091E-09 6.930E-09 6.205E-09 3.915E-09 5.417E-09 5.995E-09 4.552E-09 5.758E-09 5.945E-09 4.954E-09 4.584E-09 3.689E-09 4.163E-09 4.735E-09 4.239E-09 2.675E-09 3.701E-09 4.097E-09 3.110E-09 3.935E-09 4.063E-09 3.384E-09 3.132E-09 2.520E-09 2.843E-09 3.235E-09 2.897E-09 1.827E-09 2.530E-09 2.800E-09 2.126E-09 2.689E-09 2.775E-09 2.313E-09 2.141E-09 1.721E-09 1.943E-09 2.210E-09 1.979E-09 1.249E-09 1.728E-09 1.913E-09 1.452E-09 1.836E-09 1.897E-09 1.580E-09 1.463E-09 1.176E-09 1.328E-09 1.510E-09 1.352E-09 8.534E-10 1.181E-09 1.307E-09 9.923E-10 1.255E-09 1.296E-09 1.080E-09 9.995E-10 8.041E-10 9.073E-10 1.032E-09 9.242E-10 5.831E-10 8.069E-10 8.931E-10 6.780E-10 8.579E-10 8.856E-10 7.379E-10 6.830E-10 5.494E-10 6.200E-10 7.053E-10 6.315E-10 3.984E-10 5.513E-10 6.102E-10 4.632E-10 5.861E-10 6.050E-10 5.042E-10 4.667E-10 3.754E-10 4.236E-10 4.819E-10 4.315E-10 2.721E-10 3.767E-10 4.169E-10 3.165E-10 4.005E-10 4.134E-10 3.445E-10 3.189E-10 2.564E-10 2.894E-10 3.291E-10 2.947E-10 1.860E-10 2.573E-10 2.849E-10 2.163E-10 2.735E-10 2.824E-10 2.353E-10 2.178E-10 1.752E-10 1.976E-10 2.249E-10 2.013E-10 1.270E-10 1.758E-10 1.946E-10 1.476E-10 1.868E-10 1.928E-10 1.608E-10 1.487E-10 1.196E-10 1.350E-10 1.536E-10 1.375E-10 8.679E-11 1.201E-10 1.329E-10 1.009E-10 1.276E-10 1.317E-10 1.098E-10 1.016E-10 8.175E-11 9.224E-11 1.049E-10 9.395E-11 5.927E-11 8.202E-11 9.078E-11 6.891E-11 8.719E-11 9.000E-11 7.498E-11 6.941E-11 5.582E-11 6.300E-11 7.165E-11 6.416E-11 4.047E-11 5.601E-11 6.198E-11 4.705E-11 5.953E-11 6.143E-11 5.119E-11 4.738E-11



#�3.��(�)� *��4��-�� ************************************************************************** ***** ***** ***** A T 1 2 3 D ***** ***** ***** ***** AT123D Version 6.2 -- March, 2005 ***** ***** Copyright 2005 Environmental Software Consultants, Inc. ***** ***** ***** ***** ***** ***** Developed by: G. T. Yeh, 1979 ***** ***** Oak Ridge National Laboratory ***** ***** Oak Ridge, Tennessee, 37830 ***** ***** ***** ************************************************************************** ***** ***** ***** Modified by : John Seymor, 1982 ***** ***** and : Darryl Holman, 1984 ***** ***** University of Wisconsin-Madison ***** ***** Department of Engineering & Applied Science ***** ***** ***** ************************************************************************** ***** ***** ***** Modified by : Howard Trussell, 1986 ***** ***** Department of Civil & Environmental Engineering ***** ***** University of Wisconsin-Madison ***** ***** ***** ***** ***** ************************************************************************** ***** ***** ***** Modified by: Robert A. Schneiker, 1999-2005 ***** ***** Environmental Software Consultants, Inc. ***** ***** P.O. Box 2622 ***** ***** Madison, Wisconsin 53701-2622 ***** ***** Phone: (608) 240-9878 ***** ***** FAX: (608) 241-3991 ***** ***** ***** ************************************************************************** ***** Modified by: Robert A. Schneiker, October 2001 ***** ***** TO FIX STEADY STATE SOLUTION ERROR ***** ***** ***** ************************************************************************** Benzene in Sand NO. OF POINTS IN X-DIRECTION ...................... 7 NO. OF POINTS IN Y-DIRECTION ...................... 5 NO. OF POINTS IN Z-DIRECTION ...................... 2 NO. OF ROOTS & NO. OF SERIES TERMS ................ 500 NO. OF BEGINNING TIME STEPS ....................... 25 NO. OF ENDING TIME STEP ........................... 241 NO. OF TIME INTERVALS FOR PRINTED OUT SOLUTION .... 48 INSTANTANEOUS SOURCE CONTROL = 0 FOR INSTANT SOURCE 1 SOURCE CONDITION CONTROL = 0 FOR STEADY SOURCE .... 240 INTERMITTENT OUTPUT CONTROL = 0 NO SUCH OUTPUT .... 1 CASE CONTROL =1 THERMAL, = 2 FOR CHEMICAL, = 3 RAD 2 SOIL ORGANIC CARBON CONTENT (OC) .................. 0.50000 ORGANIC CARBON ADSORPTION COEFFICIENT (KOC) ....... 0.3100E+02 INITIAL CONTAMINANT LOAD (MG/KG) .................. 0.0000E+00 INITIAL CONTAMINANT LOAD (KG) ..................... 0.7300E+03 AQUIFER DEPTH, = 0.0 FOR INFINITE DEEP (METERS) ... 0.00000 AQUIFER WIDTH, = 0.0 FOR INFINITE WIDE (METERS) ... 0.00000 BEGIN POINT OF X-SOURCE LOCATION (METERS) ......... -1.58100 END POINT OF X-SOURCE LOCATION (METERS) ........... 1.58100 BEGIN POINT OF Y-SOURCE LOCATION (METERS) ......... -1.58100 END POINT OF Y-SOURCE LOCATION (METERS) ........... 1.58100 BEGIN POINT OF Z-SOURCE LOCATION (METERS) ......... 0.00000



END POINT OF Z-SOURCE LOCATION (METERS) ........... 0.00000 POROSITY .......................................... 0.25000 HYDRAULIC CONDUCTIVITY (METER/HOUR) ............... 0.03600 HYDRAULIC GRADIENT ................................ 0.00300 LONGITUDINAL DISPERSIVITY (METER) ................. 2.16000 LATERAL DISPERSIVITY (METER) ...................... 0.20000 VERTICAL DISPERSIVITY (METER) ..................... 0.02000 DISTRIBUTION COEFFICIENT, KD (M**3/KG) ............ 0.00016 SOURCE CONCENTRATION (mg/L) ....................... 0.00000 MOLECULAR DIFFUSION MULTIPLY BY TORTUOSITY(M**2/HR) 0.3528E-05 DECAY CONSTANT (PER HOUR) ......................... 0.0000E+00 BULK DENSITY OF THE SOIL (KG/M**3) ................ 0.1700E+04 DENSITY OF WATER (KG/M**3) ........................ 0.1000E+04 ACCURACY TOLERANCE FOR REACHING STEADY STATE ...... 0.1000E-01 TIME INTERVAL SIZE FOR THE DESIRED SOLUTION (HR) .. 0.7300E+03 DISCHARGE TIME (HR) ............................... 0.1752E+06 WASTE RELEASE RATE (KCAL/HR), (KG/HR), OR (CI/HR) . 0.7300E+03 X COORDINATES ... 0.00 5.00 10.00 15.00 20.00 25.00 30.00 Y COORDINATES ... -10.00 -5.00 0.00 5.00 10.00 Z COORDINATES ... 0.00 1.00 LIST OF TRANSIENT SOURCE RELEASE RATE 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.1061E-08 0.3764E-07 0.4469E-07 0.4058E-07 0.2573E-07 0.3576E-07 0.3971E-07 0.3021E-07 0.3831E-07 0.3961E-07 0.3305E-07 0.3063E-07 0.2465E-07 0.2784E-07 0.3169E-07 0.2839E-07 0.1791E-07 0.2480E-07 0.2746E-07 0.2086E-07 0.2639E-07 0.2726E-07 0.2271E-07 0.2102E-07 0.1691E-07 0.1909E-07 0.2171E-07 0.1945E-07 0.1227E-07 0.1698E-07 0.1879E-07 0.1427E-07 0.1805E-07 0.1863E-07 0.1553E-07 0.1436E-07 0.1156E-07 0.1304E-07 0.1484E-07 0.1329E-07 0.8386E-08 0.1160E-07 0.1284E-07 0.9750E-08 0.1233E-07 0.1273E-07 0.1061E-07 0.9821E-08 0.7901E-08 0.8916E-08 0.1014E-07 0.9082E-08 0.5730E-08 0.7928E-08 0.8775E-08 0.6661E-08 0.8428E-08 0.8701E-08 0.7250E-08 0.6710E-08 0.5398E-08 0.6091E-08 0.6930E-08 0.6205E-08 0.3915E-08 0.5417E-08 0.5995E-08 0.4552E-08 0.5758E-08 0.5945E-08 0.4954E-08 0.4584E-08 0.3689E-08 0.4163E-08 0.4735E-08 0.4239E-08 0.2675E-08 0.3701E-08 0.4097E-08 0.3110E-08 0.3935E-08 0.4063E-08 0.3384E-08 0.3132E-08 0.2520E-08 0.2843E-08 0.3235E-08 0.2897E-08 0.1827E-08 0.2530E-08 0.2800E-08 0.2126E-08 0.2689E-08 0.2775E-08 0.2313E-08 0.2141E-08 0.1721E-08 0.1943E-08 0.2210E-08 0.1979E-08 0.1249E-08 0.1728E-08 0.1913E-08 0.1452E-08 0.1836E-08 0.1897E-08 0.1580E-08 0.1463E-08 0.1176E-08 0.1328E-08 0.1510E-08 0.1352E-08 0.8534E-09 0.1181E-08 0.1307E-08 0.9923E-09 0.1255E-08 0.1296E-08 0.1080E-08 0.9995E-09 0.8041E-09 0.9073E-09 0.1032E-08 0.9242E-09 0.5831E-09 0.8069E-09 0.8931E-09 0.6780E-09 0.8579E-09 0.8856E-09 0.7379E-09 0.6830E-09 0.5494E-09 0.6200E-09 0.7053E-09 0.6315E-09 0.3984E-09 0.5513E-09 0.6102E-09 0.4632E-09 0.5861E-09 0.6050E-09 0.5042E-09 0.4667E-09 0.3754E-09 0.4236E-09 0.4819E-09 0.4315E-09 0.2721E-09 0.3767E-09 0.4169E-09 0.3165E-09 0.4005E-09 0.4134E-09 0.3445E-09 0.3189E-09 0.2564E-09 0.2894E-09 0.3291E-09 0.2947E-09 0.1860E-09 0.2573E-09 0.2849E-09 0.2163E-09 0.2735E-09 0.2824E-09 0.2353E-09 0.2178E-09 0.1752E-09 0.1976E-09 0.2249E-09 0.2013E-09 0.1270E-09 0.1758E-09 0.1946E-09 0.1476E-09 0.1868E-09 0.1928E-09 0.1608E-09 0.1487E-09 0.1196E-09 0.1350E-09 0.1536E-09 0.1375E-09 0.8679E-10 0.1201E-09 0.1329E-09 0.1009E-09 0.1276E-09 0.1317E-09 0.1098E-09 0.1016E-09 0.8175E-10 0.9224E-10 0.1049E-09 0.9395E-10 0.5927E-10 0.8202E-10 0.9078E-10 0.6891E-10 0.8719E-10 0.9000E-10 0.7498E-10 0.6941E-10



0.5582E-10 0.6300E-10 0.7165E-10 0.6416E-10 0.4047E-10 0.5601E-10 0.6198E-10 0.4705E-10 0.5953E-10 0.6143E-10 0.5119E-10 0.4738E-10 0.4738E-10 RETARDATION FACTOR ................................ 0.2054E+01 RETARDED DARCY VELOCITY (M/HR) .................... 0.2103E-03 RETARDED LONGITUDINAL DISPERSION COEF. (M**2/HR) .. 0.4612E-03 RETARDED LATERAL DISPERSION COEFFICIENT (M**2/HR) . 0.4893E-04 RETARDED VERTICAL DISPERSION COEFFICIENT (M**2/HR) 0.1108E-04 DISTRIBUTION OF CHEMICALS IN PPM AT 730.00 DAYS Z = 0.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 -5.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 5.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 10.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 Z = 1.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 -5.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 5.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 10.00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 DISTRIBUTION OF CHEMICALS IN PPM AT 2190.00 DAYS Z = 0.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.510E-08 0.103E-07 0.913E-08 0.365E-08 0.663E-09 0.555E-10 0.215E-11 -5.00 0.252E-03 0.461E-03 0.335E-03 0.108E-03 0.164E-04 0.119E-05 0.416E-07 0.00 0.558E-01 0.327E-01 0.133E-01 0.326E-02 0.425E-03 0.283E-04 0.933E-06 5.00 0.252E-03 0.461E-03 0.335E-03 0.108E-03 0.164E-04 0.119E-05 0.416E-07 10.00 0.510E-08 0.103E-07 0.913E-08 0.365E-08 0.663E-09 0.555E-10 0.215E-11 Z = 1.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.253E-08 0.509E-08 0.455E-08 0.183E-08 0.334E-09 0.281E-10 0.110E-11 -5.00 0.108E-03 0.201E-03 0.153E-03 0.514E-04 0.801E-05 0.593E-06 0.209E-07 0.00 0.597E-02 0.925E-02 0.532E-02 0.147E-02 0.203E-03 0.139E-04 0.466E-06 5.00 0.108E-03 0.201E-03 0.153E-03 0.514E-04 0.801E-05 0.593E-06 0.209E-07 10.00 0.253E-08 0.509E-08 0.455E-08 0.183E-08 0.334E-09 0.281E-10 0.110E-11 DISTRIBUTION OF CHEMICALS IN PPM AT 3650.00 DAYS Z = 0.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.938E-06 0.232E-05 0.373E-05 0.393E-05 0.276E-05 0.130E-05 0.414E-06 -5.00 0.397E-03 0.917E-03 0.127E-02 0.115E-02 0.701E-03 0.295E-03 0.863E-04 0.00 0.150E-01 0.138E-01 0.122E-01 0.882E-02 0.475E-02 0.185E-02 0.514E-03 5.00 0.397E-03 0.917E-03 0.127E-02 0.115E-02 0.701E-03 0.295E-03 0.863E-04 10.00 0.938E-06 0.232E-05 0.373E-05 0.393E-05 0.276E-05 0.130E-05 0.414E-06 Z = 1.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00



-10.00 0.649E-06 0.161E-05 0.259E-05 0.275E-05 0.194E-05 0.915E-06 0.293E-06 -5.00 0.247E-03 0.581E-03 0.832E-03 0.770E-03 0.480E-03 0.205E-03 0.604E-04 0.00 0.312E-02 0.630E-02 0.721E-02 0.568E-02 0.319E-02 0.127E-02 0.358E-03 5.00 0.247E-03 0.581E-03 0.832E-03 0.770E-03 0.480E-03 0.205E-03 0.604E-04 10.00 0.649E-06 0.161E-05 0.259E-05 0.275E-05 0.194E-05 0.915E-06 0.293E-06 DISTRIBUTION OF CHEMICALS IN PPM AT 5110.00 DAYS Z = 0.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.326E-05 0.866E-05 0.171E-04 0.253E-04 0.283E-04 0.242E-04 0.158E-04 -5.00 0.239E-03 0.606E-03 0.107E-02 0.141E-02 0.141E-02 0.110E-02 0.671E-03 0.00 0.386E-02 0.455E-02 0.565E-02 0.621E-02 0.562E-02 0.411E-02 0.240E-02 5.00 0.239E-03 0.606E-03 0.107E-02 0.141E-02 0.141E-02 0.110E-02 0.671E-03 10.00 0.326E-05 0.866E-05 0.171E-04 0.253E-04 0.283E-04 0.242E-04 0.158E-04 Z = 1.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.253E-05 0.673E-05 0.133E-04 0.198E-04 0.222E-04 0.190E-04 0.125E-04 -5.00 0.172E-03 0.441E-03 0.798E-03 0.107E-02 0.109E-02 0.855E-03 0.525E-03 0.00 0.113E-02 0.256E-02 0.387E-02 0.455E-02 0.426E-02 0.317E-02 0.187E-02 5.00 0.172E-03 0.441E-03 0.798E-03 0.107E-02 0.109E-02 0.855E-03 0.525E-03 10.00 0.253E-05 0.673E-05 0.133E-04 0.198E-04 0.222E-04 0.190E-04 0.125E-04 STEADY STATE SOLUTION HAS NOT BEEN REACHED BEFORE FINAL SIMULATING TIME DISTRIBUTION OF CHEMICALS IN PPM AT 6570.00 DAYS Z = 0.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.390E-05 0.108E-04 0.237E-04 0.419E-04 0.596E-04 0.691E-04 0.655E-04 -5.00 0.110E-03 0.293E-03 0.593E-03 0.952E-03 0.124E-02 0.134E-02 0.120E-02 0.00 0.993E-03 0.142E-02 0.218E-02 0.305E-02 0.368E-02 0.376E-02 0.324E-02 5.00 0.110E-03 0.293E-03 0.593E-03 0.952E-03 0.124E-02 0.134E-02 0.120E-02 10.00 0.390E-05 0.108E-04 0.237E-04 0.419E-04 0.596E-04 0.691E-04 0.655E-04 Z = 1.00 X Y 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -10.00 0.322E-05 0.890E-05 0.196E-04 0.347E-04 0.496E-04 0.576E-04 0.548E-04 -5.00 0.856E-04 0.230E-03 0.473E-03 0.770E-03 0.102E-02 0.111E-02 0.994E-03 0.00 0.373E-03 0.910E-03 0.163E-02 0.240E-02 0.297E-02 0.308E-02 0.268E-02 5.00 0.856E-04 0.230E-03 0.473E-03 0.770E-03 0.102E-02 0.111E-02 0.994E-03 10.00 0.322E-05 0.890E-05 0.196E-04 0.347E-04 0.496E-04 0.576E-04 0.548E-04



#"3.��(�)� *�%�!�� Anderson, M. P. and Woessner, 1992. Applied Groundwater Modeling, Academic Press, San Diego, CA. Bear, J., S. B. Milovan, and R. R. Randall, Fundamentals of Ground-Water Modeling, U. S. Environmental Protection Agency, Office of Research and Development and the Office of Solid Waste and Emergency Response, 1992, 11p. EPA/540/S-92-005. Bonazountas, M., D. H. Hetrick, P. T. Kostecki and E. J. Calabrese, SESOIL in Environmental Fate and Risk Modeling, 1997, Amherst Scientific Publishers, 661p. De Wiest, Roger J. M., Flow Through Porous Media, Academic Press, New York, 1969, pp. 401-454. Domenico, P. A., and G. A. Robins, “A New Method of Contaminant Plume Analysis,” Groundwater, Vol. 23, No. 4, July-Aug., 1985. Howard, P. H., R. S. Boethling, W. F. Jarvis, W. M. Meylan, and E. M. Michalenko, 1991. Handbook of Environmental Degradation Rates, Lewis Publishers, Inc., Chelsea, MI. Robertson, J. B., “Digital Modeling of Radioactive and Chemical Waste Transport in the Snake River Plain Aquifer at the National Reactor Testing Station, Idaho,” U.S.G.S., Open-File Report IDO-22054, 1974. Yeh, G. T., “AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste Transport in the Aquifer System,” Oak Ridge National Laboratory, Environmental Sciences Division, Publication No. 1439, March, 1981. Yeh, G. T., H. Trussel and J. Hoopes “AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste Transport in the Aquifer System,” Wisconsin Department of Natural Resources, 1987. Yeh, G. T., Y. J. Tsai, “Analytical Three-Dimensional Transient Modeling of Effluent Discharges,” Water Resources Research, Vol. 12, No. 3, pp. 533-540, June, 1976.



Appendix C

SEVIEW Text Editor Commands



$)3.�� 4��$��

Command <Alt> SEVIEW Menu

Commands

Function

File Commands <ESCAPE> File Close

Double click on file handle

Closes the file and exits the SEVIEW editor without savings any changes. Will prompt you if you want to discard the changes.

<F5> File Save Saves the file and exits the SEVIEW editor. File Save As... Saves the file with a new name.

Cursor Movement Commands

<��> The arrow keys move the cursor within the document.

<Control + �> Moves the cursor one word to the right. <Control + �> Moves the cursor one word to the left. <Page Down> Moves the cursor down one page.

<Page Up> Moves the cursor up one page. <Home> Moves the cursor to the start of the line. <End> Moves the cursor to the end of the line.

<Control + Home>

or <Control + Page

Up>

Moves the cursor to the start of the document.

<Control + Page Down>

Moves the cursor to the end of the document.

Edit Go to Line Moves cursor to specified line number. Block Commands

<Shift + Cursor Movement

Commands>

Highlights text to be copied or deleted

Edit Select All Highlights the entire document. Block Copy Commands

<Control + C> Edit Copy Copies the selected block to the clipboard. <Control + X> Edit Cut Copies the selected block to the clipboard

and deletes the highlighted text. <Control + V> Edit Paste Copies the contents of the clipboard to the

document.



SEVIEW Text Editor Commands (Continued)

Command <Alt>

SEVIEW Menu Commands

Function

Delete Commands

<Delete> Deletes the current character. Undo / Redo Command

<Control + Z> Edit Undo Undo - Un does the last command and restores the document.

<Control + R> Edit Redo Redo - Restores the previous Undo command.

Insert / Type Over Commands

<Insert> Toggles between insert and type over mode. OVR is displayed near the lower right portion of the screen.

Find / Replace Commands

<Control + F> Edit Find Finds a specified text string with the document.

<Control + G> Find Again Repeats the previous Find command.



Appendix D

SEVIEW Technical Support



*)3.�� 2�� ESCI will provide 30 days of free technical support to registered users. The 30 days of support begins when you receive your SEVIEW activation key. After the 30 days of free support registered users may obtain additional technical support.

D1.1 Technical Support

ESCI provides a one or two-year support plan. This plan includes the following services:

• Priority response

• Discount pricing on continued support

• Special mailings, including discounts on products and services

ESCI support is available for $500 per year (or $900 for two years).

D1.2 Contacting Technical Support

Environmental Software Consultants, Incorporated (ESCI) provides technical support for the SEVIEW data management program. If you have difficulty installing SEVIEW or have questions regarding the program, please consult this User’s Guide for assistance. If after consulting the User’s Guide you are still experiencing problems, contact our Technical Support Department. We will gladly assist you in the operation or configuration of the SEVIEW program. Please have the following information available.

• Version numbers of SEVIEW, SESOIL, AT123D, BIOSCREEN and Windows.

• Amount of RAM and free disk space.

• A brief description of the problem, including any error messages.

• Procedures necessary to duplicate the problem.

Technical support is available to registered users from 9:00 AM to 4:00 PM (Central Standard Time) Monday through Friday at (608) 240-9878. Technical support will be provided free for 30 days following the installation of SEVIEW.

Written correspondence may sent to our Technical Support Department at:

Environmental Software Consultants, Inc. P.O. Box 2622 Madison, Wisconsin 53701-2622

You may also fax your request for technical support to ESCI at (608) 241-3991. Please follow the guidelines presented above in any correspondence.

A feedback form is included in Appendix E. ESCI would appreciate any feedback registered users may have concerning the software, including additional features you want to see in future versions.



Appendix E

SEVIEW Feedback Form



�)3.�� -��1 5�-�� Please complete and return this for to Environmental Software Consultants, Inc. Attach additional pages if necessary. Mail to: Environmental Software Consultants Incorporated P.O. Box 2622 Madison, Wisconsin 53701-2622 Date: Name: Company Name: Company Address: Data Entry Problems Please describe the problem you found. Indicate what you were doing when you discovered the problem. Documentation Please provide the SEVIEW User’s Guide page number and describe any problems or errors you find. Additional Documentation or Features You Would Like to See Please describe the additional features you would like to see included in the Documentation/Manual. Additional Comments



�&*�6�

.

.ATI.............................................................................. 70

.ATO..................................................................150, 163

.OUT.............................................. 51, 52, 63, 150, 163

.SSF........................................................................59, 61

A

ADS ON SOIL.........................................................155 ADSORBED............................................................156 Adsorption ... 18, 89, 92, 93, 104, 113, 140, 189, 193,

194, 197, 202, 209, 251 Air diffusion coefficient ...........................92, 202, 203 Air temperature........................................................... 89 Annual cycle.............................................................182 Application........26, 54, 82, 93, 97, 99, 102, 103, 104,

105, 108, 109, 112, 117, 127, 132, 140, 151, 154, 177, 185, 191, 195, 196, 199, 206, 207, 211

Application area .......................................................207 Aquifer depth...........................................135, 232, 252 Aquifer thickness .....................................................129 Aquifer width...........................................134, 232, 252 Area 19, 40, 41, 42, 53, 105, 109, 114, 125, 135, 137,

139, 153, 154, 160, 177, 185, 198, 205, 207, 215, 226

ASCII ......................... 53, 60, 61, 62, 72, 73, 150, 163 AT123D14, 15, 16, 17, 18, 19, 20, 21, 22, 26, 28, 35,

36, 37, 38, 39, 40, 41, 42, 44, 49, 52, 53, 55, 56, 62, 63, 64, 68, 70, 71, 72, 73, 77, 78, 79, 82, 83, 96, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 163, 164, 166, 167, 169, 171, 172, 177, 222, 223, 224, 225, 226, 227, 228, 229, 231, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 254, 256, 257, 261, 266

AT123D output file..............................................39, 40

B

Biodegradation .....18, 89, 93, 95, 112, 123, 194, 195, 196, 198, 199, 203, 208

Biodegradation rate..................................................195 BIOSCREEN3, 14, 16, 17, 19, 20, 22, 26, 45, 46, 47,

48, 49, 51, 56, 75, 76, 121, 122, 123, 124, 125, 126, 129, 134, 169, 171, 177, 222, 266

Bulk density................... 133, 166, 204, 228, 233, 253

C

Calibration....................................... 183, 198, 199, 200 Cation exchange...93, 94, 96, 97, 102, 103, 112, 113,

155, 178, 188, 193, 194, 196, 197, 204, 209 Chemical .........................................................26, 56, 62

Chemical input file .....................62, 89, 111, 156, 217 CHKDSK ................................................................. 169 Clay fraction............................................................. 205 Climate.........................................................................26 Climate input file .............................................215, 216 Cloud cover .............................................................. 215 Complexation.....................93, 96, 116, 178, 197, 198 COMPLEXED ........................................................ 155 Concentration initial ................................................ 191 Concentration input ....................................................26 Contaminant depth..........................152, 156, 190, 192 Contaminant load.................................... 115, 117, 139 Corrupt files.............................................................. 169 Current directory................................... 50, 51, 62, 124

D

Data set menu.................................................56, 57, 58 Database..........................................................59, 62, 74 dBASE.................................................................... 6, 59 Default directory.................................................. 50, 51 Default Directory................................................. 50, 51 DEGRAD MOIS..................................................... 155 DEGRAD SOIL ...................................................... 155 DIFFUSED UP..................................................70, 155 Dilution factor .......................................................... 127 Disconnectedness..................................................... 100 Dispersivity............................................................... 134 Distribution coefficient........................... 166, 233, 252 DOS.................................6, 49, 55, 56, 63, 75, 77, 169

E

Effective porosity.101, 166, 167, 204, 228, 230, 231, 233, 234, 235, 237

Ending time step ...................................................... 251 Excel..........................6, 16, 58, 59, 60, 61, 72, 73, 121 Execution SESOIL file ........................................... 206

F

Find command ...................................................80, 264 Font...............................................................................52 FoxPro.................................................. 6, 59, 61, 72, 73 FREE LIGAND....................................................... 156 Freundlich exponent.......97, 103, 112, 113, 188, 193,

204, 209

G

Graphs.............................................................19, 20, 53 GWR. RUNOFF..................................... 124, 126, 155

H

Henry’s Law constant .................................18, 89, 202



Hydraulic conductivity...166, 183, 242, 244, 246, 248, 252

Hydraulic gradient.......................... 127, 129, 166, 252 HYDROL CEC........................................................155 HYDROL MOIS .....................................................155 HYDROL SOIL.......................................................155 Hydrologic cycle ..103, 117, 151, 152, 153, 154, 156,

159, 174, 176, 177, 178, 179, 180, 181, 183, 184, 185, 186, 190, 198, 200, 217

Hydrologic Cycle Report ..............................30, 31, 32 Hydrolysis ..89, 94, 111, 155, 178, 194, 196, 197, 198,

202

I

IMMOBIL CEC.......................................................155 IN SOIL AIR......................................................57, 155 IN SOIL MOI...........................................................155 IN WASHLD ...........................................................155 Installing SEVIEW.................................................... 22 Intrinsic permeability................................99, 191, 204

L

Lost data....................................................................169 LOTUS...............................................58, 59, 61, 72, 73 LOWER SOIL ZONE.......................................57, 155

M

Mass balance ............................................................158 Mass balance report .................20, 28, 29, 49, 70, 158 Mass input............................................58, 70, 152, 156 Microsoft Excel.....................................16, 59, 60, 121 Microsoft Graph...................................................19, 54 Microsoft Word.......................................19, 54, 59, 74 MOISTURE .....................................................156, 216 Molecular weight ....................... 92, 93, 194, 202, 203 Monthly cycle...........................................................182 Multiplan....................................................................... 6

N

Navigator.........................................................21, 40, 49

O

Organic carbon adsorption coefficient...................202 Organic carbon content ...........................................204 Organic carbon ratio ................................................112 OTHER SINKS .......................................................155 OTHER TRANS......................................................155

P

pH .................................. 108, 111, 194, 195, 196, 208 Pollutant depth............... 115, 156, 190, 191, 192, 200 Pollutant fate cycle....... 103, 104, 151, 177, 178, 181,

187, 189, 190, 194, 197, 199 PURE PHASE..................................................155, 156

Q

Quit SEVIEW ...................... 29, 34, 35, 40, 43, 44, 48

R

Relative Humidity.......................................................86 Run AT123D.....................................36, 37, 38, 39, 77 Run SESOIL ....21, 23, 26, 28, 36, 37, 38, 39, 45, 55,

63, 77

S

Sand fraction............................................................. 205 SCANDISK .......................................................22, 169 SED. FRAC CLAY.........................................153, 154 SED. FRAC OC ...................................................... 154 SED. FRAC SAND................................................. 154 SED. FRAC SILT ................................................... 154 SESOIL data sets 49, 51, 52, 56, 57, 58, 60, 159, 162 SESOIL input..14, 33, 38, 53, 62, 63, 65, 80, 82, 151 SESOIL output file 28, 29, 31, 32, 33, 47, 49, 50, 51,

52, 56, 57, 62, 150, 151, 157, 158, 159, 162, 163 SESOIL process..............................56, 58, 70, 71, 158 SEVIEW spreadsheet.......... 49, 56, 57, 58, 59, 60, 62 Silt fraction ............................................................... 205 Soil.......................................................... 26, 56, 57, 162 SOIL AIR ..................................................57, 155, 156 Soil compartment.... 15, 109, 174, 177, 178, 179, 186 Soil input file ...2, 26, 56, 57, 62, 93, 97, 99, 108, 162 Soil temperature................................86, 188, 190, 198 Spill index................................................................. 207 Starting time step ..................................................... 251 Summation utility .......................................................57 SUR. RUNOFF ...................................... 153, 155, 159 Symphony.......................................................61, 72, 73 System requirements ..................................................22

T

Technical Support............................................265, 266 TOTAL INPUT...................................... 154, 155, 158 Transfer data.............................................49, 51, 56, 57 Typographical conventions .......................................20

V

VisiCalc ..........................................................61, 72, 73 Visual FoxPro ..................................... 6, 59, 61, 72, 73 Volatilization...92, 116, 174, 178, 187, 189, 192, 210 VOLATILIZED ...................................................... 155

W

Washload . 74, 82, 105, 106, 107, 151, 176, 178, 184, 185, 198, 205, 206, 215

Washload cycle....151, 152, 153, 176, 178, 179, 184, 185, 186, 198, 199

Washload input file......................................26, 74, 215 Water balance..60, 159, 174, 176, 179, 180, 181, 182 Water diffusion coefficient .......................96, 130, 141

BIOSCREENNatural Attenuation DecisionSupport System

User�s ManualVersion 1.3

United StatesEnvironmental ProtectionAgency

Office of Research andDevelopmentWashington DC 20460

EPA/600/R-96/087August 1996

BIOSCREEN

Natural Attenuation Decision Support System

User�s ManualVersion 1.3

by

Charles J. Newell and R. Kevin McLeodGroundwater Services, Inc.

Houston, Texas

James R. GonzalesTechnology Transfer Division

Air Force Center for Environmental ExcellenceBrooks AFB, San Antonio, Texas

IAG #RW57936164

Project Officer

John T. WilsonSubsurface Protection and Remediation DivisionNational Risk Management Research Laboratory

Ada, Oklahoma 74820

NATIONAL RISK MANAGEMENT RESEARCH LABORATORYOFFICE OF RESEARCH AND DEVELOPMENT

U.S. ENVIRONMENTAL PROTECTION AGENCYCINCINNATI, OHIO 45268

EPA/600/R-96/087

August 1996

NOTICE

The information in this document was developed through a collaboration between the U.S.EPA (Subsurface Protection and Remediation Division, National Risk Management ResearchLaboratory, Robert S. Kerr Environmental Research Center, Ada, Oklahoma [RSKERC]) and theU.S. Air Force (U.S. Air Force Center for Environmental Excellence, Brooks Air Force Base,Texas). EPA staff contributed conceptual guidance in the development of the BIOSCREENmathematical model. To illustrate the appropriate application of BIOSCREEN, EPA contributedfield data generated by EPA staff supported by ManTech Environmental Research Services Corp,the in-house analytical support contractor at the RSKERC. The computer code for BIOSCREENwas developed by Ground Water Services, Inc. through a contract with the U.S. Air Force. GroundWater Services, Inc. also provided field data to illustrate the application of the model.

All data generated by EPA staff or by ManTech Environmental Research Services Corp werecollected following procedures described in the field sampling Quality Assurance Plan for an in-house research project on natural attenuation, and the analytical Quality Assurance Plan for ManTechEnvironmental Research Services Corp.

An extensive investment in site characterization and mathematical modeling is often necessaryto establish the contribution of natural attenuation at a particular site. BIOSCREEN is offered as ascreening tool to determine whether it is appropriate to invest in a full-scale evaluation of naturalattenuation at a particular site. Because BIOSCREEN incorporates a number of simplifyingassumptions, it is not a substitute for the detailed mathematical models that are necessary for makingfinal regulatory decisions at complex sites.

BIOSCREEN and its User�s Manual have undergone external and internal peer reviewconducted by the U.S. EPA and the U.S. Air Force. However, BIOSCREEN is made available onan as-is basis without guarantee or warranty of any kind, express or implied. Neither the UnitedStates Government (U.S. EPA or U.S. Air Force), Ground Water Services, Inc., any of the authorsnor reviewers accept any liability resulting from the use of BIOSCREEN or its documentation.Implementation of BIOSCREEN and interpretation of the predictions of the model are the soleresponsibility of the user.

ii

FOREWORD

The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation�sland, air, and water resources. Under a mandate of national environmental laws, the Agency strivesto formulate and implement actions leading to a compatible balance between human activities andthe ability of natural systems to support and nurture life. To meet these mandates, EPA�s researchprogram is providing data and technical support for solving environmental problems today andbuilding a science knowledge base necessary to manage our ecological resources wisely, understandhow pollutants affect our health, and prevent or reduce environmental risks in the future.

The National Risk Management Research Laboratory is the Agency�s center for investigationof technological and management approaches for reducing risks from threats to human health andthe environment. The focus of the Laboratory�s research program is on methods for the preventionand control of pollution to air, land, water, and subsurface resources; protection of water quality inpublic water systems; remediation of contaminated sites and ground water; and prevention andcontrol of indoor air pollution. The goal of this research effort is to catalyze development andimplementation of innovative, cost-effective environmental technologies; develop scientific andengineering information needed by EPA to support regulatory and policy decisions; and providetechnical support and information transfer to ensure effective implementation of environmentalregulations and strategies.

This screening tool will allow ground water remediation managers to identify sites wherenatural attenuation is most likely to be protective of human health and the environment. It will alsoallow regulators to carry out an independent assessment of treatability studies and remedialinvestigations that propose the use of natural attenuation.

Clinton W. Hall, DirectorSubsurface Protection and Remediation DivisionNational Risk Management Research Laboratory

iii

iv

SEVIEW Integrated Contaminant Transport and Fate Modeling System

SESOIL Link

This BIOSCREEN User’s Manual has been modified by Environmental Software Consultants Incorporated (ESCI) to include a description of the SESOIL-BIOSCREEN link within the SEVIEW Integrated Contaminant Transport and Fate Modeling System program. The changes to the original BIOSCREEN document are limited to a brief description of the BIOSCREEN parameters linked to SESOIL. A discussion of the linked SESOIL parameters was added to the BIOSCREEN data entry descriptions on pages 15, 16, 19, 20, 21, 28, 29 and 32. Additional information regarding the link to SESOIL is provided in the SEVIEW Version 5.0 User’s Guide.

BIOSCREEN is a public domain software program however, the SEVIEW Integrated Contaminant Transport and Fate Modeling System software program is only available from ESCI, is protected by the copyright laws that pertain to computer software. It is illegal to make copies of the software except for your own backup purposes, without written permission from ESCI. In particular, it is illegal to give or sell a copy of the SEVIEW software to another individual or entity.

v

TABLE OF CONTENTS

BIOSCREEN Natural Attenuation Decision Support SystemAir Force Center for Environmental Excellence Technology Transfer Division

INTRODUCTION ........................................................................................................................................................... 1

INTENDED USES FOR BIOSCREEN ..................................................................................................................1

FUNDAMENTALS OF NATURAL ATTENUATION ................................................................................2

Biodegradation Modeling ................................................................................................................................................ 2

The Air Force Natural Attenuation Initiative .............................................................................................................3

Relative Importance of Different Electron Acceptors................................................................................................4

Preferred Reactions by Energy Potential............................................................................................................4

Distribution of Electron Acceptors at Sites ........................................................................................................5

Kinetics of Aerobic and Anaerobic Reactions ...................................................................................................6

Biodegradation Capacity ..............................................................................................................................................10

BIOSCREEN CONCEPTS ........................................................................................................................................12

BIOSCREEN Model Types ..........................................................................................................................................12

Which Kinetic Model Should One Use in BIOSCREEN?......................................................................................14

BIOSCREEN DATA ENTRY ..................................................................................................................................14

1. HYDROGEOLOGIC DATA ....................................................................................................................15

2. DISPERSIVITY ................................................................................................................................................17

3. ADSORPTION DATA................................................................................................................................19

4. BIODEGRADATION DATA ..................................................................................................................21

5. GENERAL DATA .........................................................................................................................................26

6. SOURCE DATA.............................................................................................................................................27

7. FIELD DATA FOR COMPARISON ....................................................................................................33

ANALYZING BIOSCREEN OUTPUT...............................................................................................................33

Centerline Output.........................................................................................................................................................33

Array Output.................................................................................................................................................................33

Calculating the Mass Balance .................................................................................................................................34

BIOSCREEN TROUBLESHOOTING TIPS.....................................................................................................37

Minimum System Requirements ................................................................................................................................37

Spreadsheet-Related Problems .................................................................................................................................37

Common Error Messages ...........................................................................................................................................37

REFERENCES .................................................................................................................................................................39

APPENDICES

A.1 DOMENICO ANALYTICAL MODEL .......................................................................................................41

A.2 INSTANTANEOUS REACTION - SUPERPOSITION ALGORITHM .............................................43

A.3 DERIVATION OF SOURCE HALF-LIFE ..................................................................................................45

A.4 DISPERSIVITY ESTIMATES.........................................................................................................................47

A.5 ACKNOWLEDGMENTS ................................................................................................................................50

A.6 BIOSCREEN EXAMPLES ...............................................................................................................................51

BIOSCREEN User’s Manual June 1996

1

INTRODUCTION

BIOSCREEN is an easy-to-use screening model which simulates remediation through natural

attenuation (RNA) of dissolved hydrocarbons at petroleum fuel release sites. The software,

programmed in the Microsoft ÿ Excel spreadsheet environment and based on the Domenico

analytical solute transport model, has the ability to simulate advection, dispersion,

adsorption, and aerobic decay as well as anaerobic reactions that have been shown to be the

dominant biodegradation processes at many petroleum release sites. BIOSCREEN includes

three different model types:

1) Solute transport without decay,

2) Solute transport with biodegradation modeled as a first-order decay process (simple, lumped-parameterapproach),

3) Solute transport with biodegradation modeled as an "instantaneous" biodegradation reaction (approachused by BIOPLUME models).

The model is designed to simulate biodegradation by both aerobic and anaerobic reactions. It

was developed for the Air Force Center for Environmental Excellence (AFCEE) Technology

Transfer Division at Brooks Air Force Base by Groundwater Services, Inc., Houston, Texas.

INTENDED USES FOR BIOSCREEN

BIOSCREEN attempts to answer two fundamental questions regarding RNA:

1. How far will the dissolved contaminant plume extend if no engineered controlsor further source zone reduction measures are implemented?

BIOSCREEN uses an analytical solute transport model with two options for simulating

in-situ biodegradation: first-order decay and instantaneous reaction. The model will

predict the maximum extent of plume migration, which may then be compared to the

distance to potential points of exposure (e.g., drinking water wells, groundwater

discharge areas, or property boundaries). Analytical groundwater transport models

have seen wide application for this purpose (e.g., ASTM 1995), and experience has

shown such models can produce reliable results when site conditions in the plume area

are relatively uniform.

2. How long will the plume persist until natural attenuation processes cause it todissipate?

BIOSCREEN uses a simple mass balance approach based on the mass of dissolvable

hydrocarbons in the source zone and the rate of hydrocarbons leaving the source zone to

estimate the source zone concentration vs. time. Because an exponential decay in source

zone concentration is assumed, the predicted plume lifetimes can be large, usually

ranging from 5 to 500 years. Note: This is an unverified relationship as there are few

data showing source concentrations vs. long time periods, and the results should be

considered order-of-magnitude estimates of the time required to dissipate the plume.

BIOSCREEN is intended to be used in two ways:

1. As a screening model to determine if RNA is feasible at a site.

In this case, BIOSCREEN is used early in the remedial investigation to determine if an

RNA field program should be implemented to quantify the natural attenuation


2

occurring at a site. Some data, such as electron acceptor concentrations, may not be

available, so typical values are used. In addition, the model can be used to help

develop long-term monitoring plans for RNA projects.

2. As the primary RNA groundwater model at smaller sites.

The Air Force Intrinsic Remediation Protocol Wiedemeier, Wilson, et al ., 1995)

describes how groundwater models may be used to help verify that natural attenuation

is occurring and to help predict how far plumes might extend under an RNA scenario.

At large, high-effort sites such as Superfund and RCRA sites, a more sophisticated

model such as BIOPLUME is probably more appropriate. At less complicated, lower-

effort sites such as service stations, BIOSCREEN may be sufficient to complete the

RNA study. (Note: “Intrinsic remediation” is a risk-based strategy that relies on

RNA).

BIOSCREEN has the following limitations:

1. As an analytical model, BIOSCREEN assumes simple groundwater flowconditions.

The model should not be applied where pumping systems create a complicated flow

field. In addition, the model should not be applied where vertical flow gradients

affect contaminant transport.

2. As an screening tool, BIOSCREEN only approximates more complicatedprocesses that occur in the field.

The model should not be applied where extremely detailed, accurate results that

closely match site conditions are required. More comprehensive numerical models

should be applied in these cases.

FUNDAMENTALS OF NATURAL ATTENUATION

Biodegradation Modeling

Naturally occurring biological processes can significantly enhance the rate of organic mass

removal from contaminated aquifers. Biodegradation research performed by Rice University,

government agencies, and other research groups has identified several main themes that are

crucial for future studies of natural attenuation:

1. The relative importance of groundwater transport vs. microbial kinetics is a key

consideration for developing workable biodegradation expressions in models. Results

from the United Creosote site (Texas) and the Traverse City Fuel Spill site (Michigan)

indicate that biodegradation is better represented as a macro-scale wastewater

treatment-type process than as a micro-scale study of microbial reactions.

2. The distribution and avai labi l i ty of electron acceptors control the rate of in-situ

biodegradation for most petroleum release site plumes. Other factors (e.g., population

of microbes, pH, temperature, etc.) rarely limit the amount of biodegradation occurring

at these sites.

These themes are supported by the following literature. Borden et a l . (1986) developed the

BIOPLUME model, which simulates aerobic biodegradation as an “instantaneous” microbial

reaction that is limited by the amount of electron acceptor, oxygen, that is available. In other


3

words, the microbial reaction is assumed to occur at a much faster rate than the time required

for the aquifer to replenish the amount of oxygen in the plume. Although the time required for

the biomass to aerobically degrade the dissolved hydrocarbons is on the order of days, the

overall time to flush a plume with fresh groundwater is on the order of years or tens of years.

Borden e t a l . (1986) incorporated a simplifying assumption that the microbial kinetics are

instantaneous into the USGS two-dimensional solute transport model (Konikow and

Bredehoeft, 1978) using a simple superposition algorithm. The resulting model, BIOPLUME,

was able to simulate solute transport and fate under the effects of instantaneous, oxygen-

limited in-situ biodegradation.

Rifai and Bedient (1990) extended this approach and developed the BIOPLUME II model,

which simulates the transport of two plumes: an oxygen plume and a contaminant plume. The

two plumes are allowed to react, and the ratio of oxygen to contaminant consumed by the

reaction is determined from an appropriate stoichiometric model. The BIOPLUME II model is

documented with a detailed user's manual (Rifai et al., 1987) and is currently being used by EPA

regional offices, U.S. Air Force facilities, and by consulting firms. Borden et al . (1986) applied

the BIOPLUME concepts to the Conroe Superfund site; Rifai et al. (1988) and Rifai et al . (1991)

applied the BIOPLUME II model to a jet fuel spill at a Coast Guard facility in Michigan.

Many other studies using the BIOPLUME II model have been presented in recent literature.

The BIOPLUME II model has increased the understanding of biodegradation and natural

attenuation by simulating the effects of adsorption, dispersion, and aerobic biodegradation

processes in one model. It incorporates a simplified mechanism (first-order decay) for handling

other degradation processes, but does not address specific anaerobic decay reactions. Early

conceptual models of natural attenuation were based on the assumption that the anaerobic

degradation pathways were too slow to have any meaningful effect on the overall natural

attenuation rate at most sites. Accordingly, most field programs focused only on the distribution

of oxygen and contaminants, and did not measure the indicators of anaerobic activity such as

depletion of anaerobic electron acceptors or accumulation of anaerobic metabolic by-products.

The Air Force Natural Attenuation Initiative

Over the past several years, the high cost and poor performance of many pump-and-treat

remediation systems have led many researchers to consider RNA as an alternative technology

for groundwater remediation. A detailed understanding of natural attenuation processes is

needed to support the development of this remediation approach. Researchers associated with

the U.S. EPA's R.S. Kerr Environmental Research Laboratory (now the Subsurface Protection

and Remediation Division of the National Risk Management Laboratory) have suggested that

anaerobic pathways could be a significant, or even the dominant, degradation mechanism at

many petroleum fuel sites (Wilson, 1994). The natural attenuation initiative, developed by the

AFCEE Technology Transfer Division, was designed to investigate how natural attenuation

processes affect the migration of plumes at petroleum release sites. Under the guidance of Lt.

Col. Ross Miller, a three-pronged technology development effort was launched in 1993 which

will ultimately consist of the following elements:

1) Field data collected at over 30 sites around the country (Wiedemeier, Miller, et al.,

1995) analyzing aerobic and anaerobic processes.

2) A Technical Protocol, outlining the approach, data collection techniques, and da ta

analysis methods required for conducting an Air Force RNA Study (Wiedemeier,

Wilson, et al., 1995).

3) Two RNA modeling tools: the BIOPLUME III model being developed by Dr. Hanadi

Rifai at Rice University (Rifai et al., 1995), and the BIOSCREEN model developed by


4

Groundwater Services, Inc. (BIOPLUME III, a more sophisticated biodegradation

model than BIOSCREEN, employs particle tracking of both hydrocarbon and alternate

electron acceptors using a numerical solver. The model employs sequential degradation

of the biodegradation reactions based on zero order, first order, instantaneous, or Monod

kinetics).

Relative Importance of Different Electron Acceptors

The Intrinsic Remediation Technical Protocol and modeling tools focus on evaluating both

aerobic (in the presence of oxygen) and anaerobic (without oxygen) degradation processes. In

the presence of organic substrate and dissolved oxygen, microorganisms capable of aerobic

metabolism will predominate over anaerobic forms. However, dissolved oxygen is rapidly

consumed in the interior of contaminant plumes, converting these areas into anoxic (low-oxygen)

zones. Under these conditions, anaerobic bacteria begin to utilize other electron acceptors to

metabolize dissolved hydrocarbons. The principal factors influencing the utilization of the

various electron acceptors by fuel-hydrocarbon-degrading bacteria include: 1) the relative

biochemical energy provided by the reaction, 2) the availability of individual or specific

electron acceptors at a particular site, and 3) the kinetics (rate) of the microbial reaction

associated with the different electron acceptors.

Preferred Reactions by Energy Potential

Biologically mediated degradation reactions are reduction/oxidation (redox) reactions,

involving the transfer of electrons from the organic contaminant compound to an electron

acceptor. Oxygen is the electron acceptor for aerobic metabolism, whereas nitrate, ferric iron,

sulfate, and carbon dioxide can serve as electron acceptors for alternative anaerobic pathways.

This transfer of electrons releases energy which is utilized for microbial cell maintenance and

growth. The biochemical energy associated with alternative degradation pathways can be

represented by the redox potential of the alternative electron acceptors: the more positive the

redox potential, the more energetically favorable the reaction. With everything else being

equal, organisms with more efficient modes of metabolism grow faster and therefore dominate

over less efficient forms.

ElectronAcceptor

Type ofReaction

MetabolicBy-Product

ReactionPreference

Oxygen Aerobic CO 2 Most Preferred

Nitrate Anaerobic N 2, CO2

Ferric Iron(solid)

Anaerobic Ferrous Iron

(dissolved)

Sulfate Anaerobic H 2S

Carbon Dioxide Anaerobic Methane Least Preferred

Based solely on thermodynamic considerations, the most energetically preferred reaction

should proceed in the plume until all of the required electron acceptor is depleted. At that

point, the next most-preferred reaction should begin and continue until that electron acceptor is

consumed, leading to a pattern where preferred electron acceptors are consumed one at a time, in

sequence. Based on this principle, one would expect to observe monitoring well data with "no

detect" results for the more energetic electron acceptors, such as oxygen and nitrate, in locations


5

where evidence of less energetic reactions is observed (e.g. monitoring well data indicating the

presence of ferrous iron).

In practice, however, it is unusual to collect samples from monitoring wells that are completely

depleted in one or more electron acceptors. Two processes are probably responsible for this

observation:

1. Alternative biochemical mechanisms exhibiting very similar energy potentials (such

as aerobic oxidation and nitrate reduction) may occur concurrently when the preferred

electron acceptor is reduced in concentration, rather than fully depleted. Facultative

aerobes (bacteria able to utilize electron acceptors in both aerobic and anaerobic

environments), for example, can shift from aerobic metabolism to nitrate reduction

when oxygen is still present but at low concentrations (i.e. 1 mg/L oxygen; Snoeyink and

Jenkins, 1980). Similarly, the nearly equivalent redox potentials for sulfate and carbon

dioxide (see Wiedemeier, Wilson, et al. , 1995) indicate that sulfate reduction and

methanogenic reactions may also occur together.

2. Standard monitoring wells, with 5- to 10- foot screened intervals, will mix waters from

different vertical zones. If different biodegradation reactions are occurring at different

depths, then one would expect to find geochemical evidence of alternative degradation

mechanisms occurring in the same well. If the dissolved hydrocarbon plume is thinner

than the screened interval of a monitoring well, then the geochemical evidence of

electron acceptor depletion or metabolite accumulation will be diluted by mixing with

clean water from zones where no degradation is occurring.

Therefore, most natural attenuation programs yield data that indicate a general pattern of

electron acceptor depletion, but not complete depletion, and an overlapping of electron

acceptor/metabolite isopleths into zones not predicted by thermodynamic principles. For

example, a zone of methane accumulation may be larger than the apparent anoxic zone.

Nevertheless, these general patterns of geochemical changes within the plume area provide

strong evidence that multiple mechanisms of biodegradation are occurring at many sites. The

BIOSCREEN software attempts to account for the majority of these biodegradation

mechanisms.

Distribution of Electron Acceptors at Sites

The utilization of electron acceptors is generally based on the energy of the reaction and the

availability of the electron acceptor at the site. While the energy of each reaction is based on

thermodynamics, the distribution of electron acceptors is dependent on site-specific

hydrogeochemical processes and can vary significantly among sites. For example, a study of

several sites yielded the following summary of available electron acceptors and metabolic by-

products:


6

Measured Background Electron Acceptor/By-Product Concentration (mg/L)

Base FacilityBackground

OxygenBackground

NitrateMaximum

Ferrous IronBackground

SulfateMaximumMethane

POL Site,Hill AFB, Utah*

6.0 36.2 55.6 96.6 2.0

Hangar 10 Site,Elmendorf AFB, Alaska*

0.8 64.7 8.9 25.1 9.0

Site ST-41,Elmendorf AFB,Alaska*

12.7 60.3 40.5 57.0 1.5

Site ST-29,Patrick AFB, Florida*

3.8 0 2.0 0 13.6

Bldg. 735,Grissom AFB, Indiana

9.1 1.0 2.2 59.8 1.0

SW MU 66 Site,Keesler AFB, MS

1.7 0.7 36.2 22.4 7.4

POL B Site,Tyndall AFB, Florida

1.4 0.1 1.3 5.9 4.6

*Data collected by Parsons Engineering Science, Inc.; all other data collected by Groundwater Services, Inc.

At the Patrick AFB site, nitrate and sulfate are not important electron acceptors while the

oxygen and the methanogenic reactions dominate (Wiedemeier, Swanson, et al., 1995). At Hill

AFB and Grissom AFB, the sulfate reactions are extremely important because of the large

amount of available sulfate for reduction. Note that different sites in close proximity can have

quite different electron acceptor concentrations, as shown by the two sites at Elmendorf AFB.

For data on more sites, see Table 1.

Kinetics of Aerobic and Anaerobic Reactions

As described above, aerobic biodegradation can be simulated as an “instantaneous” reaction

that is limited by the amount of electron acceptor (oxygen) that is available. The microbial

reaction is assumed to occur at a much faster rate than the time required for the aquifer to

replenish the amount of oxygen in the plume (Wilson et al. , 1985). Although the time required

for the biomass to aerobically degrade the dissolved hydrocarbons is on the order of days, the

overall time to flush a plume with fresh groundwater is on the order of years or tens of years.

For example, microcosm data presented by Davis et a l . (1994) show that microbes in an

environment with an excess of electron acceptors can degrade high concentrations of dissolved

benzene very rapidly. In the presence of surplus oxygen, aerobic bacteria can degrade ~1 mg/L

dissolved benzene in about 8 days, which can be considered relatively fast (referred to as

“instantaneous”) compared to the years required for flowing groundwater to replenish the

plume area with oxygen.

BIOSCREEN User’s Manual June 19 96

7

TABLE 1

BIODEGRADATION CAPACITY (EXPRESSED ASSIMILATIVE CAPACITY) AT AFCEE NATURAL ATTENUATION SITES

BIOSCREEN Natural Attenuation Decision Support System

MaximumTotal BTEX Biodegradation Capacity/Expressed Assimilative Capacity (mg/L) Total

Site Concentration Observed Change in Concentration (mg/L) Aerobic Iron Sulfate Biodegradation Source of

Number Base State Site Name (mg/L) O2 Nitrate Iron Sulfate Methane Respiration Denitrification Reduction Reduction Methanogenesis Capacity (mg/L) Data

1 Hill AFB Utah 21.5 6.0 36.2 55.6 96.6 2.0 1.9 7.4 2.6 21.0 2.6 35.4 PES2 Battle Creek ANGB Michigan 3.6 5.7 5.6 12.0 12.9 8.4 1.8 1.1 0.6 2.8 10.8 17.1 PES3 Madison ANGB Wisconsin 28.0 7.2 45.3 15.3 24.2 11.7 2.3 9.2 0.7 5.3 15.0 32.5 PES4 Elmendorf AFB Alaska Hangar 10 22.2 0.8 64.7 8.9 25.1 9.0 0.3 13.2 0.4 5.5 11.6 30.9 PES5 Elmendorf AFB Alaska ST-41 30.6 12.7 60.3 40.5 57.0 1.5 4.0 12.3 1.9 12.4 1.9 32.5 PES

6 King Salmon AFB Alaska FT-001 10.1 9.0 12.5 2.5 6.8 0.2 2.9 2.6 0.1 1.5 0.2 7.2 PES7 King Salmon AFB Alaska Naknek 5.3 11.7 0 44.0 0 5.6 3.7 0 2.0 0 7.2 12.9 PES8 Plattsburgh AFB New York 6.0 10.0 3.7 10.7 18.9 0.3 3.2 0.7 0.5 4.1 0.4 8.9 PES9 Eglin AFB Florida 3.7 1.2 0 8.9 4.9 11.8 0.4 0 0.4 1.1 15.2 17.0 PES10 Patrick AFB Florida 7.3 3.8 0 2.0 0 13.6 1.2 0 0.1 0 17.4 18.7 PES

11 MacDill AFB Florida Site 56 29.6 2.4 5.6 5.0 101.2 13.6 0.8 1.1 0.2 22.0 17.4 41.5 PES12 MacDill AFB Florida Site 57 0.7 2.1 0.5 20.9 62.4 15.4 0.7 0.1 1.0 13.6 19.7 35.0 PES13 MacDill AFB Florida Site OT-24 2.8 1.3 0 13.1 3.7 9.8 0.4 0 0.6 0.8 12.6 14.4 PES14 Offutt AFB Nebraska FPT-A3 3.2 0.6 0 19.0 32.0 22.4 0.2 0 0.9 7.0 28.8 36.8 PES15 Offutt AFB Nebraska 103.0 8.4 69.7 0 82.9 0 2.7 14.2 0 18.0 0 34.9 PES

16 Westover AFRES Massachusetts FT-03 1.7 10.0 8.6 599.5 33.5 0.2 3.2 1.8 27.5 7.3 0.2 40.0 PES17 Westover AFRES Massachusetts FT-08 32.6 9.9 17.2 279.0 11.7 4.3 3.1 3.5 12.8 2.6 5.5 27.5 PES18 Myrtle Beach South Carolina 18.3 0.4 0 34.9 20.7 17.2 0.1 0 1.6 4.5 22.0 28.2 PES19 Langley AFB Virginia 0.1 6.4 23.5 10.9 81.3 8.0 2.0 4.8 0.5 17.7 10.2 35.3 PES20 Griffis AFB New York 12.8 4.4 52.5 24.7 82.2 7.1 1.4 10.7 1.1 17.9 9.1 40.2 PES

21 Rickenbacker ANGB Ohio 1.0 1.5 35.9 17.9 93.2 7.7 0.5 7.3 0.8 20.3 9.8 38.7 PES22 Wurtsmith AFB Michigan SS-42 3.1 8.5 25.4 19.9 10.6 1.4 2.7 5.2 0.9 2.3 1.8 12.9 PES23 Travis AFB Califonia - 3.8 15.8 8.5 109.2 0.2 1.2 3.2 0.4 23.7 0.3 28.9 PES24 Pope AFB North Carolina 8.2 7.5 6.9 56.2 9.7 48.4 2.4 1.4 2.6 2.1 62.0 70.5 PES25 Seymour Johnson AFB North Carolina 13.8 8.3 4.3 31.6 38.6 2.7 2.6 0.9 1.5 8.4 3.5 16.8 PES

26 Grissom AFB Indiana Bldg. 735 0.3 9.1 1.0 2.2 59.8 1.0 2.9 0.2 0.1 13.0 1.2 17.4 GSI27 Tyndall AFB Florida POL B 1.0 1.4 0.1 1.3 5.9 4.6 0.5 0 0.1 1.3 5.9 7.7 GSI28 Keesler AFB Mississippi SWMU 66 14.1 1.7 0.7 36.2 22.4 7.4 0.5 0.1 1.7 4.9 9.5 16.7 GSI

Average 14.2 5.6 17.7 49.3 39.5 8.4 1.8 3.6 2.3 8.6 10.8 27.0Median 7.3 5.8 6.3 16.6 24.6 7.2 1.9 1.3 0.8 5.4 9.3 28.5

Maximum 103.0 12.7 69.7 599.5 109.2 48.4 4.0 14.2 27.5 23.7 62.0 70.5Minimum 0.1 0.4 0 0 0 0 0.1 0 0 0 0 7.2

Note: 1. Utilization factors of the electron acceptors/by-products are as follows (mg of electron acceptor or by-product/mg of BTEX): Dissolved Oxygen: 3.14, Nitrate: 4.9, Iron: 21.8, Sulfate: 4.7, Methane: 0.78. 2. - = Data not available. 3. PES = Parsons Engineering Science (Wiedemeier, Miller, et al. 1995). GSI = Groundwater Services, Inc.


8

Recent results from the AFCEE Natural Attenuation Initiative indicate that the anaerobic

reactions, which were originally thought to be too slow to be of significance in groundwater, can

also be simulated as instantaneous reactions (Newell et al . , 1995). For example, Davis e t a l .

(1994) also ran microcosm studies with sulfate reducers and methanogens that indicated that

benzene could be degraded in a period of a few weeks (after acclimation). When compared to

the time required to replenish electron acceptors in a plume, it appears appropriate to simulate

anaerobic biodegradation of dissolved hydrocarbons with an instantaneous reaction, just as for

aerobic biodegradation processes.

This conclusion is supported by observing the pattern of anaerobic electron acceptors and

metabolic by-products along the plume at RNA research sites:

If microbial kinetics were limiting therate of biodegradation:

If microbial kinetics were relatively fast(instantaneous):

• Anaerobic electron acceptors (nitrate and

sulfate) would be constantly decreasing in

concentration as one moved downgradient

from the source zone, and

• Anaerobic electron acceptors (nitrate and

sulfate) would be mostly or totally

consumed in the source zone, and

• Anaerobic by-products (ferrous iron and

methane) would be constantly increasing

in concentration as one moved

downgradient from the source zone.

• Anaerobic by-products (ferrous iron and

methane) would be found in the highest

concentrations in the source zone.

BTEX

O2, NO3, SO4

FE2+, CH4

X

BTEXObserved

Conc.

Conc.

Conc.

Conc.

Conc.

O2, NO3, SO4

X

BTEX

ObservedConc.

FE2+, CH4

The second pattern is observed at RNA demonstration sites (see Figure 1), supporting the

hypothesis that anaerobic reactions can be considered to be relatively instantaneous at most or

almost all petroleum release sites. From a theoretical basis, the only sites where the

instantaneous reaction assumption may not apply are sites with very low hydraulic residence

times (very high groundwater velocities and short source zone lengths).


9

0.0

0.5

0

5

10

0

25

0

2

4

0 100 200 300

0

20

40

0

2

4

0 200 400 600 800

1.0Tyndall

0 500 1000 1500 2000

0

4

8

0

50

100

0

3

6

Hill

Patrick ElmendorfST-41

0.0

5.0

10.0

0

10

20

0

25

0 200 400 600 800

Keesler

0.0

0.1

0.2

0

10

20

02

46

0 1000 2000 3000 4000

ElmendorfHG-10

BTEX

D. Oxygen

Methane

Nitrate

Sulfate

Iron

BTEX

Methane

Nitrate

Sulfate

Iron

BTEX

Methane

Nitrate

Sulfate

Iron

D. Oxygen

D. Oxygen

Distance along plume centerline Distance along plume centerline

Co

nce

ntr

atio

n (

mg

/L)

Co

nce

ntr

atio

n (

mg

/L)

0

5

10

0

5

10

0

10

0 200 400 600 800

Co

nce

ntr

atio

n (

mg

/L)

Figure 1. Distribution of BTEX, Electron Acceptors, and Metabolic By-Products vs. Distance Along Centerlineof Plume.

Sampling Date and Source of Data: Tyndall 3/95 , Keesler 4/95 (Groundwater Services, Inc.), Patrick 3/94 (note: one NO3

outlier removed, sulfate not plotted), Hill 7/93, Elmendorf Site ST41 6/94, Elmendorf Site HG 10 6/94, (ParsonsEngineering Science).


10

Kinetic-limited sites, however, appear to be relatively rare as the instantaneous reaction

pattern is observed even at sites such as Site 870 at Hill AFB, with residence times of a month

or less. As shown in Figure 1, this site has an active sulfate reducing and methane production

zone within 100 ft of the upgradient edge of plume. With a 1600 ft/yr seepage velocity is

considered, this highly anaerobic zone has an effective residence time of 23 days. Despite this

very short residence time, significant sulfate depletion and methane production were observed

in this zone (see Figure 1). If the anaerobic reactions were significantly constrained by

microbial kinetics, the amount of sulfate depletion and methane production would be much less

pronounced. Therefore this site supports the conclusion that the instantaneous reaction

assumption is applicable to almost all petroleum release sites.

Biodegradation Capacity

To apply an electron-acceptor-limited kinetic model, such as the instantaneous reaction, the

amount of biodegradation able to be supported by the groundwater that moves through the

source zone must be calculated. The conceptual model used in BIOSCREEN is:

1. Groundwater upgradient of the source contains electron acceptors.

2. As the upgradient groundwater moves through the source zone, non-aqueous phase

liquids (NAPLs) and contaminated soil release dissolvable hydrocarbons (in the case of

petroleum sites, the BTEX compounds benzene, toluene, ethylbenzene, xylene are

released).

3. Biological reactions occur until the available electron acceptors in groundwater are

consumed. (Two exceptions to this conceptual model are the iron reactions, where the

electron acceptor, ferric iron, dissolves from the aquifer matrix; and the methane

reactions, where the electron acceptor, CO 2 is also produced as an end-product of the

reactions. For these reactions, the metabolic by-products, ferrous iron and methane, can

be used as proxies for the potential amount of biodegradation that could occur from the

iron-reducing and methanogenesis reactions.)

4. The total amount of available electron acceptors for biological reactions can be

estimated by a) calculating the difference between upgradient concentrations and source

zone concentrations for oxygen, nitrate, and sulfate; and b) measuring the production of

metabolic by-products (ferrous iron and methane) in the source zone.

5. Using stoichiometry, a utilization factor can be developed showing the ratio of the

oxygen, nitrate, and sulfate consumed to the mass of dissolved hydrocarbon degraded in

the biodegradation reactions. Similarly, utilization factors can be developed to show

the ratio of the mass of metabolic by-products that are generated to the mass of

dissolved hydrocarbon degraded in the biodegradation reactions. Wiedemeier,

Wilson, et al . , (1995) provides the following utilization factors based on the

degradation of combined BTEX constituents:

Electron Acceptor/By-Product BTEX Utilization Factor gm/gm

Oxygen 3.14

Nitrate 4.9

Ferrous Iron 21.8

Sulfate 4.7

Methane 0.78


11

6. For a given background concentration of an individual electron acceptor, the potential

contaminant mass removal or "biodegradation capacity" depends on the "utilization

factor" for that electron acceptor. Dividing the background concentration of an electron

acceptor by its utilization factor provides an estimate (in BTEX concentration units) of

the assimilative capacity of the aquifer by that mode of biodegradation.

Note that BIOSCREEN is based on the BTEX utilization provided above. If other

constituents are modeled, the utilization factors in the software (scroll down from the

input screen to find the utilization factors) should be changed or the available oxygen,

nitrate, iron, sulfate, and methane data should be adjusted accordingly to reflect

alternate utilization factors.

When the available electron acceptor/by-product concentrations (No. 4) are divided by

the appropriate utilization factor (No. 5), an estimate of the "biodegradation

capacity" of the groundwater flowing through the source zone and plume can be

developed. The biodegradation capacity is then used directly in the BIOSCREEN

model to simulate the effects of an instantaneous reaction. The suggested calculation

approach to develop BIOSCREEN input data is:

Biodegradation Capacity (mg/L) =

{ (Average Upgradient Oxygen Conc.) - (Minimum Source Zone Oxygen Conc) } / 3.14

+ { (Average Upgradient Nitrate Conc.) - (Minimum Source Zone Nitrate Conc) } /4.9

+ { (Average Upgradient Sulfate Conc.) - (Minimum Source Zone Sulfate Conc) } / 4.7

+ { Average Observed Ferrous Iron Conc. in Source Area} / 21.8

+ { Average Observed Methane Conc. in Source Area } / 0.78

Biodegradation capacity is similar to “expressed assimilative capacity” described in

the AFCEE Technical Protocol, except that expressed assimilative capacity is based on

the maximum observed concentration observed in the source zone for iron and methane,

while the biodegradation capacity term used in BIOSCREEN is based on the average

concentration in the source zone for iron and methane. BIOSCREEN uses the more

conservative biodegradation capacity approach to provide a conservative screening

tool to users. Calculated biodegradation capacities (from Groundwater Services sites)

and expressed assimilative capacities (from Parsons Engineering-Science sites) at

different U.S. Air Force RNA research sites have ranged from 7 to 70 mg/L (see Table

1). The median capacity for 28 AFCEE sites is 28.5 mg/L.

Note that one criticism of this lumped biodegradation capacity approach is that it

assumes that all of the various aerobic and anaerobic reactions occur over the entire

area of the contaminant plume, and that the theoretical “zonation” of reactions is not

simulated in BIOSCREEN (e.g. typically dissolved oxygen utilization occurs at the

downgradient portion and edges of the plume, nitrate utilization a little closer to the

source, iron reduction in the middle of the plume, sulfate reduction near the source, and

methane production in the heart of the source zone). A careful inspection of actual field

data (see Figure 1) shows little or no evidence of this theoretical zonation of reactions;

in fact all of the reactions appear to occur simultaneously in the source zone. The most

common pattern observed at petroleum release sites is that ferrous iron and methane

seems to be restricted to the higher-concentration or source zone areas, with the other

reactions (oxygen, nitrate, and sulfate depletion), occurring throughout the plume.


12

BIOSCREEN assumes that all of the biodegradation reactions (aerobic and anaerobic)

occur almost instantaneously relative to the hydraulic residence time in the source area

and plume. Because iron reduction and methane production appear to occur only in the

source zone (probably due to the removal of these metabolic by-products) it is

recommended to use the average iron and methane concentrations observed in the source

zone for the calculation of biodegradation capacity instead of maximum concentrations.

In addition, the iron and methane concentrations are used during a secondary

calibration step (see below). Beta testing of BIOSCREEN indicated that the use of the

maximum concentration of iron and methane tended to overpredict biodegradation at

many sites by assuming these reactions occurred over the entire plume area. Use of an

average value (or some reduced value) helps match actual field data.

7. Note that at some sites the instantaneous reaction model will appear to overpredict

the amount of biodegradation that occurs, and underpredict at others. As with the case

of the first-order decay model, some calibration to actual site conditions is required.

With the first-order decay, the decay coefficient is adjusted arbitrarily until the

predicted values match observed field conditions. With the instantaneous reaction

model, there is no first-order decay coefficient to adjust, so the following procedure is

recommended:

A) The primary calibration step (if needed) is to manipulate the model’s dispersivity

values. As described in the BIOSCREEN Data Entry Section below, values for

dispersivity are related to aquifer scale (defined as the plume length or distance to

the measurement point) and simple relationships are usually applied to estimate

dispersivities. Gelhar et al. (1992) cautions that dispersivity values vary between

2-3 orders of magnitude for a given scale due to natural variation in hydraulic

conductivity at a particular site. Therefore dispersivity values can be manipulated

within a large range and still be within the range of values observed at field test

sites. In BIOSCREEN, adjusting the transverse dispersivity alone will usually be

enough to calibrate the model.

B) As a secondary calibration step, the biodegradation capacity calculation may be

reevaluated. There is some judgment involved in averaging the electron acceptor

concentrations observed in upgradient wells; determining the minimum oxygen,

nitrate and sulfate in the source zone; and estimating the average ferrous iron and

methane concentrations in the source zone. Although probably not needed in most

applications, these values may be adjusted as a final level of calibration.

BIOSCREEN CONCEPTS

The BIOSCREEN Natural Attenuation software is based on the Domenico (1987) three-

dimensional analytical solute transport model. The original model assumes a fully-penetrating

vertical plane source oriented perpendicular to groundwater flow, to simulate the release of

organics to moving groundwater. In addition, the Domenico solution accounts for the effects of

advective transport, three-dimensional dispersion, adsorption, and first-order decay. In

BIOSCREEN, the Domenico solution has been adapted to provide three different model types

representing i) transport with no decay, ii) transport with first-order decay, and iii) transport

with "instantaneous" biodegradation reaction (see Model Types). Guidelines for selecting key

input parameters for the model are outlined in BIOSCREEN Input Parameters. For help on

Output, see BIOSCREEN Output.


13

BIOSCREEN Model Types

The software allows the user to see results from three different types of groundwater transport

models, all based on the Domenico solution:

1. Solute transport with no decay. This model is appropriate for predicting the movement

of conservative (non-degrading) solutes such as chloride. The only attenuation

mechanisms are dispersion in the longitudinal, transverse, and vertical directions, and

adsorption of contaminants to the soil matrix.

2. Solute transport with first-order decay. With this model, the solute degradation rate

is proportional to the solute concentration. The higher the concentration, the higher

the degradation rate. This is a conventional method for simulating biodegradation in

dissolved hydrocarbon plumes. Modelers using the first-order decay model typically

use the first-order decay coefficient as a calibration parameter, and adjust the decay

coefficient until the model results match field data. With this approach, uncertainties

in a number of parameters (e.g., dispersion, sorption, biodegradation) are lumped

together in a single calibration parameter.

Literature values for the half-life of benzene, a readily biodegradable dissolved

hydrocarbon, range from 10 to 730 days while the half-life for TCE, a more recalcitrant

constituent, is 10.7 months to 4.5 years (Howard et al., 1991). Other applications of the

first-order decay approach include radioactive solutes and abiotic hydrolysis of

selected organics, such as dissolved chlorinated solvents. One of the best sources

of first-order decay coefficients in groundwater systems is The Handbook of

Environmental Degradation Rates (Howard et al . , 1991).

The first-order decay model does not account for site-specific information such as the

availability of electron acceptors. In addition, it does not assume any biodegradation of

dissolved constituents in the source zone. In other words, this model assumes

biodegradation starts immediately downgradient of the source, and that it does not

depress the concentrations of dissolved organics in the source zone itself.

3. Solute transport with "instantaneous" biodegradation reaction. Modeling work

conducted by GSI indicate first-order expressions may not be as accurate for describing

natural attenuation processes as the instantaneous reaction assumption (Connor et a l . ,

1994). Biodegradation of organic contaminants in groundwater is more difficult to

quantify using a first-order decay equation because electron acceptor limitations are not

considered. A more accurate prediction of biodegradation effects may be realized by

incorporating the instantaneous reaction equation into a transport model. This

approach forms the basis for the BIOSCREEN instantaneous reaction model.

To incorporate the instantaneous reaction in BIOSCREEN, a superposition method was

used. By this method, contaminant mass concentrations at any location and time within

the flow field are corrected by subtracting 1 mg/L organic mass for each mg/L of

biodegradation capacity provided by all of the available electron acceptors, in

accordance with the instantaneous reaction assumption. Borden et al . (1986) concluded

that this simple superposition technique was an exact replacement for more

sophisticated oxygen-limited expressions, as long as the oxygen and hydrocarbon had

the same transport rates (e.g., retardation factor, R = 1). Connor et al . (1994) revived

this approach for use in spreadsheets and compared the results to those from more

sophisticated but difficult to use numerical models. They found this approach to work

well, even for retardation factors greater than 1, so this superposition approach was

incorporated into the BIOSCREEN model (see Appendix A.2).


14

Which Kinetic Model Should One Use in BIOSCREEN?

BIOSCREEN gives the user three different models to choose from to help see the effect of

biodegradation. At almost all petroleum release sites, biodegradation is present and can be

verified by demonstrating the consumption of aerobic and anaerobic electron acceptors.

Therefore, results from the No Biodegradation model are intended only to be used for

comparison purposes and to demonstrate the effects of biodegradation on plume migration.

Some key factors for comparison of the First-order Decay model and the Instantaneous Reaction

model are presented below:

FACTOR First-Order Decay ModelInstantaneous

Reaction Model

Able to Utilize Data fromAFCEE Intrinsic RemediationProtocol?

• No - Does not account forelectron acceptors/by-products

• Yes - Accounts for availability ofelectron acceptors and by-products

Simple to Use? • Yes • Yes

Simplification of NumericalModel?

• Yes - many numerical modelsinclude first-order decay

• Yes - Simplification ofBIOPLUME III model

Familiar to Modelers? • More commonly used • Used less frequently

Key Calibration Parameter • First-Order Decay Coefficients • Source Term/Dispersivity

Over - or UnderestimatesSource Decay Rate?

• May underpredict rate ofsource depletion (see Newellet al., 1995)

• May be more accurate forestimating rate of sourcedepletion (see Newell et al., 1995)

A key goal of the AFCEE Natural Attenuation Initiative is to quantify the magnitude of RNA

based on field measurements of electron acceptor consumption and metabolic by-product

production. Therefore, the Instantaneous Reaction model is recommended either alone or in

addition to the first-order decay model (if appropriate calibration is performed) for most sites

where the Intrinsic Remediation Technical Protocol (Wiedemeier, Wilson, e t a l., 1995) has

been applied. For a more rigorous analysis of natural attenuation, the BIOPLUME III model (to

be released in late 1996) may be more appropriate.

BIOSCREEN DATA ENTRY

Three important considerations regarding data input are:

1 To see the example data set in the input screen of the software, click on the “Paste

Example Data Set” button on the lower right portion of the input screen.

2) Because BIOSCREEN is based on the Excel spreadsheet, you have to click outside of

the cell where you just entered data or hit “return” before any of the buttons will

work.

3) Several cells have data that can be entered directly or can be calculated by the model

using data entered in the grey cells (e.g., seepage velocity can be entered directly or

calculated using hydraulic conductivity, gradient, and effective porosity). If the

calculation option does not appear to work, check to make sure that there is still a

formula in the cell. If not, you can restore the formula by clicking on the “Restore

Formulas” button on the bottom right hand side of the input screen. If there still

appears to be a problem, click somewhere outside of the last cell where you entered

data and then click on the “Recalculate” button on the input screen.


15

1. HYDROGEOLOGIC DATA

Parameter Seepage Velocity (Vs)

Units ft/yr

Description Actual interstitial groundwater velocity, equaling Darcy velocity divided by effective porosity. Note that the Domenico model and BIOSCREEN are not formulated to simulate the effects of chemical diffusion. Therefore, contaminant transport through very slow hydrogeologic regimes (e.g., clays and slurry walls) should probably not be modeled using BIOSCREEN unless the effects of chemical diffusion are proven to be insignificant. Domenico and Schwartz (1990) indicate that chemical diffusion is insignificant for Peclet numbers (seepage velocity times median pore size divided by the bulk diffusion coefficient) > 100.

Typical Values 0.5 to 200 ft/yr

Source of Data Calculated by multiplying hydraulic conductivity by hydraulic gradient and dividing by effective porosity. It is strongly recommended that actual site data be used for hydraulic conductivity and hydraulic gradient data parameters; effective porosity can be estimated.

How to Enter Data 1) Enter directly or 2) Fill in values for hydraulic conductivity, hydraulic gradient, and effective porosity as described below and have BIOSCREEN calculate seepage velocity. Note: if the calculation option does not appear to work, check to make sure that the cell still contains a formula. If not, you can reincarnate the formula by clicking on the “Restore Formulas” button on the bottom right hand side of the input screen. If there is still a problem, make sure to click somewhere outside of the last cell where you entered data and then click on the “Recalculate” button on the input screen.

Parameter Hydraulic Conductivity (K)

Units cm/sec




Source of Data Pump tests or slug tests at the site. It is strongly recommended that actual site data be used for most RNA studies.

How to Enter Data Enter directly. If seepage velocity is entered directly, this parameter is not needed in BIOSCREEN.

SEVIEW Link Soil permeability cm/sec (K1 in the SESOIL soil input file or the lower most permeability in the SESOIL application file if K1 = zero).

Note: SEVIEW converts the intrinsic permeability to cm/sec by multiplying by 1x105 prior to transferring the value.


16

Parameter Hydraulic Gradient (i)

Units ft/ft



Source of Data Calculated by constructing potentiometric surface maps using static water level data from monitoring wells and estimating the slope of the potentiometric surface.

How to Enter Data Enter directly. If seepage velocity is entered directly, this parameter is not needed in BIOSCREEN.

Parameter Effective Porosity (n)

Units unitless

Description Dimensionless ratio of the volume of interconnected voids to the bulk volume of the aquifer matrix. Note that “total porosity” is the ratio of all voids (included non-connected voids) to the bulk volume of the aquifer matrix. Difference between total and effective porosity reflect lithologic controls on pore structure. In unconsolidated sediments coarser than silt size, effective porosity can be less than total porosity by 2-5% (e.g. 0.28 vs, 0.30) (Smith and Wheatcraft, 1993).

Typical Values Values for Effective Porosity:

Clay 0.01 - 0.20 Sandstone 0.005 - 0.10 Silt 0.01 - 0.30 Unfract. Limestone 0.001 - 0.05 Fine Sand 0.10 - 0.30 Fract. Granite 0.00005 - 0.01 Medium Sand 0.15 - 0.30 Coarse Sand 0.20 - 0.35 Gravel 0.10 - 0.35 (From Wiedemeier, Wilson, et al.,

1995; originally from Domenico and Schwartz, 1990 and Walton, 1988).

(From Domenico and Schwartz, 1990)

Source of Data Typically estimated. One commonly used value for silts and sands is an effective porosity of 0.25. The ASTM RBCA Standard (ASTM, 1995) includes a default value of 0.38 (to be used primarily for unconsolidated deposits).

How to Enter Data Enter directly. Note that if seepage velocity is entered directly, this parameter is still needed to calculate the retardation factor and plume mass.

SEVIEW Link The effective porosity for the SESOIL soil column (N in the SESOIL soil input file).


17

2. DISPERSIVITY

Parameter Longitudinal Dispersivity (alpha x)Transverse Dispersivity (alpha y)Vertical Dispersivity (alpha z)

Units ft

Description Dispersion refers to the process whereby a plume will spread out in a

longitudinal direction (along the direction of groundwater flow),

transversely (perpendicular to groundwater flow), and vertically

downwards due to mechanical mixing in the aquifer and chemical

diffusion. Selection of dispersivity values is a difficult process,

given the impracticability of measuring dispersion in the field.

However, simple estimation techniques based on the length of the

plume or distance to the measurement point (“scale”) are available

from a compilation of field test data. Note that researchers indicate

that dispersivity values can range over 2-3 orders of magnitude for a

given value of plume length or distance to measurement point

(Gelhar e t a l ., 1992). In BIOSCREEN, dispersivity is used as the

primary calibration parameter (see pg 12). For more information on

dispersivity, see Appendix A.4, pg 47).

Typical Values Typical dispersivity relationships as a function of Lp (plume length

or distance to measurement point in ft) are provided below.

BIOSCREEN is programmed with some commonly used relationships

representative of typical and low-end dispersivities:

• Longitudinal Dispersivity

Alpha x =

3.28 ÿ 0.83 ÿ log10

Lp

3.28

2.414

(Xu and Eckstein, 1995)

(Lp in ft)

• Transverse Dispersivity

Alpha y= 0.10 alpha x (Based on high reliability points from Gelhar et al., 1992)

• Vertical Dispersivity

Alpha z = very low (i.e. 1 x 10 -99 ft) (Based on conservative estimate)

Other commonly used relationships include:

Alpha x = 0.1 Lp (Pickens and Grisak, 1981)

Alpha y = 0.33 alpha x (ASTM, 1995) (EPA, 1986)

Alpha z = 0.05 alpha x (ASTM, 1995)

Alpha z = 0.025 alpha x to 0.1 alpha x (EPA, 1986)

Source of Data Typically estimated using the relationships provided above (see

Appendix A.4, pg 47).

How to EnterData

1) Enter directly or 2) Fill in value of the estimated plume length and

have BIOSCREEN calculate the dispersivities.


18

Parameter Estimated Plume Length (Lp)

Units ft

Description Estimated length (in feet) of the existing or hypothetical

groundwater plume being modeled. This is a key parameter as it is

generally used to estimate the dispersivity terms (dispersivity is

difficult to measure and field data are rarely collected).

Typical Values For BTEX plumes, 50 - 500 ft. For chlorinated solvents, 50 to 1000 ft.

Source of Data To simulate an actual plume length or calibrate to actual plume data,

enter the actual length of the plume. If trying to predict the maximum

extent of plume migration, use one of the two methods below.

1) Use seepage velocity, retardation factor, and simulation time to

estimate plume length. While this may underestimate the plume

length for a non-degrading solute, it may overestimate the plume

length for either the first-order decay model or instantaneous reaction

model if biodegradation is significant.

2) Estimate a plume length, run the model, determine how long the

plume is predicted to become (this will vary depending on the type of

kinetic expression that is used), reenter this value, and then rerun the

model. Note that considerable time and effort can be expended trying

to adjust the estimated plume length term to match exactly the

predicted modeling length. In practice, most modelers make the

assumption that dispersivity values are not very precise, and

therefore select ball-park values based on estimated plume lengths

that are probably ± 25% of the actual plume length used in the

simulations. Note that BIOSCREEN is very sensitive to the

dispersion estimates, particularly for the instantaneous reaction

model.

How to EnterData

Enter directly. If dispersivity data are entered directly, this

parameter is not needed in BIOSCREEN.


19

3. ADSORPTION DATA

Parameter Retardation Factor (R)

Units unitless

Description The rate at which dissolved contaminants moving through an aquifer can be reduced by sorption of contaminants to the solid aquifer matrix. The degree of retardation depends on both aquifer and constituent properties. The retardation factor is the ratio of the groundwater seepage velocity to the rate that organic chemicals migrate in the groundwater. A retardation value of 2 indicates that if the groundwater seepage velocity is 100 ft/yr, then the organic chemicals migrate at approximately 50 ft/yr.

BIOSCREEN simulations using the instantaneous reaction assumption at sites with retardation factors greater than 6 should be performed with caution and verified using a more sophisticated model such as BIOPLUME III (see Appendix A.2).

Typical Values 1 to 2 (for BTEX in typical shallow aquifers)

Source of Data Usually estimated from soil and chemical data using variables described below (ρb = bulk density, n = porosity, Koc = organic carbon-water partition coefficient, Kd = distribution coefficient, and foc = fraction organic carbon on uncontaminated soil) with the following expression:

RK

n

d b= +

⋅1

ρ where Kd = Koc• foc

In some cases, the retardation factor can be estimated by comparing the length of a plume affected by adsorption (such as the benzene plume) with the length of plume that is not affected by adsorption (such as chloride). Most plumes do not have both types of contaminants, so it is more common to use the estimation technique (see data entry boxes below).

How to Enter Data 1) Enter directly or 2) Fill in the estimated values for bulk density, partition coefficient, and fraction organic carbon as described below and have BIOSCREEN calculate retardation.

Parameter Soil Bulk Density ( b )

Units kg/L or g/cm 3

Description Bulk density, in kg/L, of the aquifer matrix (related to porosity and pure solids density).

Typical Values Although this value can be measured in the lab, in most cases estimated values are used. A value of 1.7 kg/L is used frequently.

Source of Data Either from an analysis of soil samples at a geotechnical lab or more commonly, application of estimated values such as 1.7 kg/L.

How to Enter Data Enter directly. If the retardation factor is entered directly, this parameter is not needed in BIOSCREEN.

SEVIEW Link The average dry soil bulk density (g/cm3) for the soil column (RS in the SESOIL soil input file).


20

Parameter Organic Carbon Partition Coefficient (Koc)

Units (mg/kg) / (mg/L) or (L/kg) or (mL/g) or (µg/g)/(µg/ml)

Description Chemical-specific partition coefficient between soil organic carbon and the aqueous phase. Larger values indicate greater affinity of contaminants for the organic carbon fraction of soil. This value is chemical specific and can be found in chemical reference books. Note that many users of BIOSCREEN will simulate BTEX as a single constituent. In this case, either an average value for the BTEX compounds can be used, or it can be assumed that all of the BTEX compounds have the same mobility as benzene (the constituent with the highest potential risk to human health).

Typical Values Benzene Toluene (ASTM, 1995)

38 L/kg 135 L/kg

Ethylbenzene Xylene

95 L/kg 240 L/kg

(Note that there is a wide range of reported values; for example, Mercer and Cohen (1990) report a Koc for benzene of 83 L/kg.

Source of Data Chemical reference literature or relationships between Koc and solubility or Koc and the octanol-water partition coefficient (Kow).

How to Enter Data Enter directly. If the retardation factor is entered directly, this parameter is not needed in BIOSCREEN.

SEVIEW Link The adsorption coefficient of the compound on organic carbon µg/g/ g/ml (KOC in the SESOIL chemical file)

Parameter Fraction Organic Carbon (foc)

Units unitless

Description Fraction of the aquifer soil matrix comprised of natural organic carbon in uncontaminated areas. More natural organic carbon means higher adsorption of organic constituents on the aquifer matrix.

Typical Values 0.0002 - 0.02

Source of Data The fraction organic carbon value should be measured if possible by collecting a sample of aquifer material from an uncontaminated zone and performing a laboratory analysis (e.g. ASTM Method 2974-87 or equivalent). If unknown, a default value of 0.001 is often used (e.g., ASTM 1995).

How to Enter Data Enter directly. If the retardation factor is entered directly, this parameter is not needed in BIOSCREEN

SEVIEW Link The organic carbon content of the uppermost soil layer (OC from the SESOIL soil input file). Note: SEVIEW converts the organic carbon percentage value used in SESOIL to a fraction value by dividing by 100.


21

4. BIODEGRADATION DATA

Parameter First-Order Decay Coefficient (lambda)

Units 1/yr

Description Rate coefficient describing first-order decay process for dissolved constituents. The first-order decay coefficient equals 0.693 divided by the half-life of the contaminant in groundwater. In BIOSCREEN, the first-order decay process assumes that the rate of biodegradation depends only on the concentration of the contaminant and the rate coefficient. For example, consider 3 mg/L benzene dissolved in water in a beaker. If the half-life of the benzene in the beaker is 728 days, then the concentration of benzene 728 days from now will be 1.5 mg/L (ignoring volatilization and other losses).

Considerable care must be exercised in the selection of a first-order decay coefficient for each constituent in order to avoid significantly over-predicting or under-predicting actual decay rates. Note that the amount of degradation that occurs is related to the time the contaminants spend in the aquifer, and that this parameter is not related to the time it takes for the source concentrations to decay by half.

Typical Values 0.1 to 36 yr -1 (see half-life values)

Source of Data Optional methods for selection of appropriate decay coefficients are as follows:

Literature Values: Various published references are available listing decay half-life values for hydrolysis and biodegradation (e.g., see Howard et al., 1991). Note that many references report the half-lives; these values can be converted to the first-order decay coefficients using k = 0.693 / t1/2 (see dissolved plume half-life).

Calibrate to Existing Plume Data: If the plume is in a steady-state or diminishing condition, BIOSCREEN can be used to determine first-order decay coefficients that best match the observed site concentrations. One may adopt a trial-and-error procedure to derive a best-fit decay coefficient for each contaminant. For still-expanding plumes, this steady-state calibration method may over-estimate actual decay-rate coefficients and contribute to an under-estimation of predicted concentration levels.

How to Enter Data 1) Enter directly or 2) Fill in the estimated half life values as described below and have BIOSCREEN calculate the first-order decay coefficients.

SEVIEW Link The liquid phase biodegradation rate of the compound (KDEL in the SESOIL chemical input file). Note: SEVIEW converts KDEL from units of 1/day to 1/yr prior to transferring the data.


22

Parameter Dissolved Plume Solute Half-Life (t1/2)

Units years

Description Time, in years, for dissolved plume concentrations to decay by one

half as contaminants migrate through the aquifer. Note that the

amount of degradation that occurs is related to the time the

contaminants spend in the aquifer, and that the degradation IS

NOT related to the time it takes for the source concentrations to

decay by half.

Modelers using the first-order decay model typically use the first-

order decay coefficient as a calibration parameter, and adjust the

decay coefficient until the model results match field data. With

this approach, uncertainty in a number of parameters (e.g.,

dispersion, sorption, biodegradation) are lumped together in a

single calibration parameter.

Considerable care must be exercised in the selection of a first-order

decay coefficient for each contaminant in order to avoid

significantly over-predicting or under-predicting actual decay

rates.

Typical Values Benzene 0.02 to 2.0 yrs

Toluene 0.02 to 0.17 yr

Ethylbenzene 0.016 to 0.62 yr

Xylene 0.038 to 1 yr

(from ASTM, 1995)

Source of Data Optional methods for selection of appropriate decay coefficients

are as follows:

Literature Values: Various published references are available

listing decay half-life values for hydrolysis and biodegradation

(e.g., see Howard et al., 1991).

Calibrate to Existing Plume Data: If the plume is in a steady-state

or diminishing condition, BIOSCREEN can be used to determine

first-order decay coefficients that best match the observed site

concentrations. A trial-and-error procedure may be adopted to

derive a best-fit decay coefficient for each contaminant. For

expanding plumes, this steady-state calibration method may over-

estimate actual decay-rate coefficients and contribute to an under-

estimation of predicted concentration levels.

How to Enter Data Enter directly. If the first-order decay coefficient is entered

directly, this parameter is not needed in BIOSCREEN.


23

Parameter Delta Oxygen (O2)

Units mg/L

Description This parameter, used in the instantaneous reaction model, is one

component of the total biodegradation capacity of the groundwater

as it flows through the source zone and contaminant plume. The

model assumes that 3.14 mg of oxygen are required to consume 1 mg

of BTEX (Wiedemeier, Wilson, et al . , 1995). Note that this

parameter is used for the instantaneous reaction model, which is

appropriate only for readily biodegradable compounds such as

BTEX that degrade according to the assumed BIOSCREEN

utilization factors, and is not appropriate for more recalcitrant

compounds such as the chlorinated solvents.

Typical Values Data from 28 AFCEE sites (see Table 1):

Median = 5.8 mg/L Maximum = 12.7 mg/L Minimum = 0.4 mg/L

Source of Data For planning studies, typical values taken from Table 1 can be used.

For actual RNA studies, the Air Force Intrinsic Remediation

Technical Protocol (Wiedemeier, Wilson, et a l . , 1995) should be

applied. Enter the average background concentration of oxygen

minus the lowest observed concentration of oxygen in the source

area. BIOSCREEN automatically applies the utilization factor

used to compute a biodegradation capacity.

How to Enter Data Enter directly.

Parameter Delta Nitrate (NO3)

Units mg/L




model assumes that 4.9 mg of nitrate are required to consume 1 mg of

BTEX (Wiedemeier, Wilson, et al . , 1995). Note that this







Median = 6.3 mg/L Maximum = 69.7 mg/L Minimum = 0 mg/L



Technical Protocol (Wiedemeier, Wilson, et a l . , 1995) should be

applied. Enter the average background concentration of nitrate

minus the lowest observed concentration of nitrate in the source

area. BIOSCREEN automatically applies the utilization factor to

compute a biodegradation capacity.



24

Parameter Observed Ferrous Iron (Fe2+)

Units mg/L



as it flows through the source zone and contaminant plume. Ferrous

iron is a metabolic by-product of the anaerobic reaction where solid

ferric iron is used as an electron acceptor. The model assumes that

21.8 mg of ferrous iron represents the consumption of 1 mg of BTEX

(Wiedemeier, Wilson, et al. , 1995). Note that this parameter is

used for the instantaneous reaction model, which is appropriate

only for readily biodegradable compounds such as BTEX that

degrade according to the assumed BIOSCREEN utilization factors,

and is not appropriate for more recalcitrant compounds such as the

chlorinated solvents.

Because ferrous iron reacts with the sulfide produced from the

reduction of sulfate, some or most of the ferrous iron may not be

observed during groundwater sampling. Some researchers suspect

that the observed ferrous iron concentration is much less (10% or

less) than the actual amount of ferrous iron that has been generated

due to the sorption of ferrous iron onto the aquifer matrix (Lovely,

1995). If this is the case, then the value used for this parameter

should be much higher than the observed maximum concentration

of ferrous iron in the aquifer.





Technical Protocol (Wiedemeier, Wilson, e t a l . , 1995) should be

applied. Enter the average observed concentration, in mg/L, of

ferrous (dissolved) iron found in the source area (approximately

the area where ferrous iron has been observed in monitoring wells).

BIOSCREEN automatically applies the utilization factor to

compute a biodegradation capacity.



25

Parameter Delta Sulfate (SO4)

Units mg/L




model assumes that 4.7 mg of sulfate are required to consume 1 mg of

BTEX (Wiedemeier, Wilson, et al . , 1995). Note that this











applied. Enter the average background concentration of sulfate

minus the lowest observed concentration of sulfate in the source

area. BIOSCREEN then computes a biodegradation capacity.


Parameter Observed Methane (CH4)

Units mg/L



as it flows through the source zone and contaminant plume.

Methane is a metabolic by-product of methanogenic activity. The

model assumes that 0.78 mg of methane represents the consumption

of 1 mg of BTEX (Wiedemeier, Wilson, et al., 1995). Note that this







Median = 7.2 mg/L Maximum = 48.4 mg/L Minimum = 0.0 mg/L




applied. Enter the average observed concentration of methane

found in the source area (approximately the area where methane

is observed in monitoring wells). BIOSCREEN automatically

computes a biodegradation capacity.



26

5. GENERAL DATA

Parameter Model Area Length and Width (L and W)

Units ft

Description Physical dimensions (in feet) of the rectangular area to be

modeled. To determine contaminant concentrations at a particular

point along the centerline of the plume (a common approach for

most risk assessments), enter this distance in the "Modeled Area

Length" box and see the results by clicking on the "Run Centerline"

button.

If one is interested in more accurate mass calculations, make sure

most of the plume is within the zone delineated by the Modeled

Area Length and Width. Find the mass balance results using the

"Run Array" button.

Typical Values 10 to 1000 ft

Source of Data Values should be slightly larger than the final plume dimensions

or should extend to the downgradient point of concern (e.g., point of

exposure). If only the centerline output is used, the plume width

parameter has no effect on the results.


Parameter Simulation Time (t)

Units years

Description Time (in years) for which concentrations are to be calculated. For

steady-state simulations, enter a large value (i.e., 1000 years

would be sufficient for most sites).

Typical Values 1 to 1000 years

Source of Data To match an existing plume, estimate the time between the

original release and the date the field data were collected. To

predict the maximum extent of plume migration, increase the

simulation time until the plume no longer increases in length.



27

6. SOURCE DATA

Parameter Source Thickness In Saturated Zone (z)

Units f t

Description The Domenico (1987) model assumes a vertical plane source ofconstant concentration. For many fuel spill sites the thickness ofthis source zone is only 5 - 20 ft, as petroleum fuels are LNAPLs(light non-aqueous phase liquids) that float on the water table.Therefore, the residual source zones that are slowly dissolving,creating the dissolved BTEX plume, are typically restricted to theupper part of the aquifer.

Surface

Top of Water-Bearing Unit

Bottom of Water-Bearing Unit

Source Thickness Z

Typical Values 5-50 ft

Source of Data This value is usually determined by evaluating groundwater datafrom wells near the source zone screened at different depths. If thistype of information is not available, then one could estimate theamount of water table fluctuation that has occurred since the time ofthe release and use this value as the source zone thickness (equatingto the smear zone). Otherwise, a simple assumption of 10 feet wouldprobably be appropriate for many petroleum release sites. Notethat if DNAPLs are present at the site (e.g., a chlorinated solventsite), a larger source zone thickness would probably be required.



28

Parameter Source Zone Width

Units f t

Description The Domenico (1987) model assumes a vertical plane source ofconstant concentration. BIOSCREEN expands the simple one source-zone approach by allowing up to five source zones with differentconcentrations to account for spatial variations in the source area.

Typical Values 10 - 200 ft

Source of Data To define a varying source concentration across the site:

1) Draw a line perpendicular to the groundwater flow direction inthe source zone. The source zone is typically defined as being thearea with contaminated soils having high concentrations of sorbedorganics, free-phase NAPLs, or residual NAPLs. If the source zonecovers a large area, it is best to choose the most downgradient orwidest point in the source area to draw the perpendicular-to-flowline.

2) Divide the line into 1, 3, or 5 zones. A total of 5 zones is shown onthe input screen.

3) Determine the width and corresponding average concentration ofZones 1, 2, and 3. Typically Zone 3 will contain the highestconcentration. Note that the model assumes the source zone issymmetrical and will automatically define source zones 4 and 5 to beidentical to Zones 2 and 1. Therefore, it is not necessary to specify a l l5 zones. For simpler problems, you can either use three zones to definevarying source concentrations across the site (enter information inZones 2 and 3, and the model will define Zone 4) or just use a singlezone (enter data for Zone 3 only).

4) Enter the width and source concentration into the appropriatezones on the spreadsheet For example, if a total source width of 100ft. is divided into five zones, enter 20 ft for each zone width. Enterthe average concentration observed across each zone.

Need Width andConcentrationof Source Zones

Surface



12345



29

Parameter Source Zone Concentration

Units mg/L

Description BIOSCREEN requires source zone concentrations that correspond to the source zone width data (see previous page). Suggested rules of thumb regarding how to handle multiple constituents are:

1) If the maximum plume length is desired, model lumped constituents (such as BTEX). If a risk assessment is being performed, data on individual constituents are needed.

2) If lumped constituents are being modeled (BTEX all together), use either average values for the chemical-specific data (Koc and lambda) or the worst-case values (e.g., use the lowest of the Koc and lambda from the group of constituents being modeled) to overestimate concentrations. Most modeling will be performed assuming that the ratio of BTEX at the edge of the plume is t he same as at the source. For more detailed modeling studies, Wilson (1996) has proposed the following rules of thumb to help account for different rates of reaction among the BTEX compounds:

If the site is dominated by aerobic degradation (most of the biodegradation capacity is from oxygen, a relatively rare occurrence) assume that the benzene will degrade first and that the dissolved material at the edge of the plume is primarily TEX.

If the site is dominated by nitrate utilization (most of the biodegradation capacity is from nitrate, a relatively rare occurrence) assume that benzene will degrade last and that the dissolved material at the edge of the plume is primarily benzene.

If the site is dominated by sulfate reduction (most of the biodegradation capacity is due to sulfate utilization, a more common occurrence) assume that the benzene will degrade at t he same rate as the TEX constituents and that the dissolved material at the edge of the plume is a mixture of BTEX.

If the site is dominated by methane production (most of the biodegradation capacity is due to methanogenesis, a more common occurrence) assume that benzene will degrade last and that t he dissolved material at the edge of the plume is primarily benzene.

3) If individual constituents are being modeled with the instantaneous reaction assumption, note that the total biodegradation capacity must be reduced to account for electron acceptor utilization by other constituents present in the plume. For example, in order to model benzene as an individual constituent using the instantaneous reaction model in a BTEX plume containing equal source concentrations of benzene, toluene, ethylbenzene and xylene, the amount of oxygen, nitrate, sulfate, iron, and methane should be reduced by 75% to account for utilization by toluene, ethylbenzene, and xylene.

Typical Values 0.010 to 120 mg/L

Source of Data Source area monitoring well data (see figure on previous page).


SEVIEW Link Maximum predicted SESOIL leachate concentration. Note: SEVIEW can apply a groundwater dilution factor to the maximum SESOIL leachate concentration. See Section 6.3.1 of the SEVIEW User’s Guide Version 5.0.


30

Parameter Source Half-Life (Value Calculated by Model)

Units years

Description The Domenico (1987) model assumes the source is infinite, i.e. the sourceconcentrations are constant. In BIOSCREEN, however, an approximation fora declining source concentration has been added. Note that this is anexperimental relationship, and it should be applied with caution. Thedeclining source term is based on the following assumptions:

• There is a finite mass of organics in the source zone present as a free-phaseor residual NAPL. The NAPL in the source zone dissolves slowly as freshgroundwater passes through.

• The change in source zone concentration can be approximated as a first-order decay process. For example, if the source zone concentration "ha l f -life" is 10 years and the initial source zone concentration is 1 mg/L, then thesource zone concentration will be 0.5 mg/L after 10 years, and 0.25 mg/Lafter 20 years.

Note that the assumption that dissolution is a first-order process is only anapproximation, and that source attenuation is best described by first-orderdecay when concentrations are relatively low (< 1 mg/L). For moreinformation on dissolution, see Newell et al., (1994). The source half- l i feIS NOT related to lambda, the biodegradation half-life for dissolvedconstituents. Lambda is used to calculate the amount of biodegradation ofdissolved organics after they leave the source zone and travel through theplume area. The source half-life is related to the rate of dissolutionoccurring in the source zone, and describes the change in sourceconcentrations over time.

• The BIOSCREEN software automatically calculates the source zoneconcentration half-life if the user enters a best estimate for the mass ofdissolvable organics zone (soluble organic constituents sorbed on the soil,residual NAPLs, and free product) in the source. The half-life of thedissolution process can be approximated if one knows the mass ofdissolvable organics in the source zone (in mg or kg), the flow rate throughthe source zone, and the average concentration of dissolved organics tha tleave the source zone. The equation is based on integrating theconcentration vs. time relationship (first-order decay) and using therelationship that the mass in the source zone over time is proportional tothe source concentration over time. This yields the following expression forthe half-life of the concentration of dissolved organics in the source zone(see Appendix A.3):

t half source = (0.693 * M0 ) / (Q * C0) where:

Q

M 0 C0

Ctt 1/2

t half source = Half-life of source

concentration (yrs)

Q = Groundwater flow through source zone (L/yr)

C0 = Effective source zone conc. (observed concentration + biodeg capacity for inst. react. assumption) at t = 0 (mg/L)

M0 = Mass of dissolvable organics in source zone at t = 0 (mg)


31

Parameter Source Half-Life (Value Calculated by Model)(Cont’d)

Description (cont’d)

Key Questions:

Why are there two source half-lives reported? Note tha tBIOSCREEN automatically selects the correct source half-life valuedepending on which kinetic model is being used (see Which ModelShould One Use? under BIOSCREEN Concepts).

Two source half-lives are reported by the model in the source hal f -life cell: the smaller number will be the source half-life fromdissolution if Instantaneous Reaction kinetics are used, and the largervalue will be for No Degradation or First-order Decay kinetics. Thefirst-order decay model assumes biodegradation starts immediatelydowngradient of the source, and that the rate of dissolution isreflected by the concentration of dissolved organics actuallymeasured in monitoring wells. In other words, the first-order decaymodel assumes C0 is equal to the observed source concentration.

The instantaneous reaction model assumes biodegradation is occurringdirectly in the source zone, and that the effective source zoneconcentration C0 is equal to the measured concentration in the source

zone plus any “missing” concentration due to biodegradation. Forexample, if the source zone concentration in monitoring wells is 5mg/L, and the biodegradation capacity is 10 mg/L, the effectivesource concentration C0 (concentration before biodegradation) is 15

mg/L. In other words, C0 is equal to the measured source

concentration plus the biodegradation capacity provided by theelectron acceptor concentration. This means use of the instantaneousreaction assumption will result in higher dissolution rates andshorter source lifetimes ( see Newell et al., 1995).

Does BIOSCREEN account for travel time away from the decliningsource? With the declining source option in BIOSCREEN, theconcentration for any location and any time is calculated using asource concentration determined by the first-order decay calculationsshown above. The time used to determine the source concentration isadjusted to account for the travel time between the source andmeasurement point.

For example, consider the case where a declining source term is usedwith a source half-life of 10 years and a solute velocity of 100 ft/yr.To calculate the concentration at a point 2000 ft away at time = 30years, BIOSCREEN follows these steps

1) Calculates travel time from point to source: 2000/100 = 20 years

2) Subtracts travel time from simulation time: 30 yrs - 20 yrs = 10 yrs

3) Calculates source decay coeff.: ksource = 0.693/(source half-life)

4) Calculates source conc. at t = 10 yr: C10 = C0 exp(-ksource x10 yrs)

Typical Values 1 to 10,000 years

Source of Data Calculated by model from soluble mass in NAPL and soil (see below),source concentrations, and groundwater velocity.

How to Enter Data Calculated directly by model. Change by changing soluble mass.


32

Parameter Soluble Mass in NAPL, Soil

Units kg

Description The best estimate of dissolvable organics in the source zone isobtained by adding the mass of dissolvable organics on soils, free-phase NAPLs, and residual NAPLs. This quantity is used toestimate the rate that the source zone concentration declines. Notethat this is an experimental and unverified model that should beapplied with care (the model probably underpredicts removal rate).

For gasoline or JP-4 spills, BTEX is usually assumed to comprise thebulk of dissolvable organics in the source zone. To simulate adeclining source, use the method described below. For constant-sourcesimulations, either enter a very large number for soluble mass in thesource zone (e.g., 1,000,000 kg) or type "Infinite".

Typical Values 0.1 to 100,000 kg

Source of Data This information will most likely come from either:

1) Estimates of the mass of spilled fuel (remember to convert thetotal mass of spilled fuel to the dissolvable mass; for example BTEXrepresents only 5-15% of the total mass of gasoline).

2) Integration of maps showing contaminated soil zones (data inmg/kg) and/or NAPL zones (usually product thickness). The usershould estimate the volume of contaminated soil, convert to kg ofcontaminated soil, and multiply by the average soil concentration.To make the estimate more accurate, the user might have to dividethe soil into different zones of soil concentrations, into unsaturatedvs. saturated soil, and/or into different depths. (One standardapproach is to divide into a vertically averaged unsaturated zonemap and a vertically averaged saturated zone map.) If the user ismaking estimates from NAPL data, remember the thickness ofproduct in a aquifer is only 10-50% of the actual product thickness inthe well (Bedient et al., 1994).

Note that the data is to be entered in kg, and the model will convertthe results to estimate the source half-life. An example is providedbelow assuming a bulk density of 1.7 kg/L (e.g., 100 ft2 x 20 ft x 28.3L/ft3 x 1.7 kg/L x 600 mg/Kg x 10-6 kg/mg = 58 kg):

100 sq. ft Depth 20 ft

Average Soil Concentration= 600 mg/Kg BTEX

Soil Area 1:



Soil Zone 2:



Soil Zone 3:

SOLUBLEMASS

TOTAL SOLUBLE MASS

Plume

ModelSourceZone 58 Kg

11 Kg

4 Kg

73 Kg



33

7. FIELD DATA FOR COMPARISON

Parameter Field Data for Comparison

Units mg/L

Description These parameters are concentrations of dissolved organics in wells

near the centerline of the plume. These data are used to help

calibrate the model and are displayed with model results in the

"Run Centerline" option.

Typical Values 0.001 to 50 mg/L

Source of Data Monitoring wells located near the centerline of the plume.

How to Enter Data Enter as many or as few of these points as needed. The data are used

only to help calibrate the model when comparing the results from

the centerline option. Note that the distance from source values

cannot be changed; use the closest value possible.

ANALYZING BIOSCREEN OUTPUT

The output shows concentrations along the centerline (for all three kinetic models at the same

time) or as an array (one kinetic model at a time). Note that the results are all for the time

entered in the “Simulation Time” box.

Centerline Output

Centerline output is displayed when the "Run Centerline" button is pressed on the input screen.

The centerline output screen shows the average concentration at the top of the saturated zone

(Z=0) along the centerline of the plume (Y=0). Clicking on “Animate” divides the simulation

into 10 separate time periods and shows the movement of the plume based on the three

BIOSCREEN models (red: no degradation, blue: first-order decay, green: instantaneous

reaction). Note that all concentrations are displayed in units of mg/L.

Array Output

The array output is displayed when the "Run Array" button is pressed on the Input screen. The

user is asked to select one of the three model types (no degradation, first-order decay, or

instantaneous reaction). A 3-D graphic shows results on a 10-point-long by 5-point-wide grid.

To alter the modeled area, adjust the Model Area Length and Width parameters on the input

screen.

To see the plume array that exceeds a certain target level (such as an MCL or risk-based

cleanup level), enter the target level in the box and push “Plot Data > Target”. Only sections of

the plume exceeding the target level will be displayed. To see all the data again, push “Plot

All Data”. Note that BIOSCREEN automatically resets this button to “Plot All Data” when

the “Run Array” button is pressed on the input screen. An approximate mass balance is

presented on the array output screen as described below.


34

Calculating the Mass Balance

Plume Mass if No Biodegradation(kg)

The model calculates the total amount of dissolved contaminant that has left the source zone.

If the source is an infinite source, then the calculation is based on the discharge of

groundwater through the source zone (Darcy velocity for groundwater times the total source

width times the source depth) times the average concentration of the source zone (a weighted

average of concentration and source length for each of the different source zones) times the

simulation time.

If the source is a declining source, an exponential source decay term is used to estimate the

mass of organics that have left the source zone (see Source Data: Varying Concentrations

Over Time). Note that the source decay term is for dissolution of soluble organics from the

source zone and is not related to the first-order decay term for the dissolved constituents.

Note that the total mass in the plume is the same for the No Degradation and First-order

Decay models but is different for the Instantaneous Reaction model. The source zone

dissolution rate is calculated to be much higher if the instantaneous reaction model is

selected. The instantaneous reaction assumes that active biodegradation reactions occur in

the source zone, and that the observed concentrations of organics in source zone monitoring

wells reflect conditions after biodegradation. In this case, the actual concentration of

organics coming off the source zone is equal to the measured concentration plus the

biodegradation capacity of the upgradient groundwater. The resulting higher effective

dissolution rate equates to a greater amount of mass leaving the source area, leading to

different mass values for the Instantaneous Reaction model.

Actual Plume Mass(kg)

BIOSCREEN calculates the mass of organics in the 5x10 plume array for the three models:

1) No Degradation 2) 1st Order Decay 3) Instantaneous Reaction

The mass is calculated by assuming that each point represents a cell equal to the incremental

width and length (except for the first column which is assumed to be half as long as the

other columns because the source is assumed to be in the middle of the cell). The volume of

affected groundwater in each cell is calculated by multiplying the area of each cell by the

source depth and by porosity (the mass balance calculation assumes 2-D transport). The mass

of organics in each cell is then determined by multiplying the volume of groundwater by the

concentration and then by the retardation factor (to account for sorbed constituents).

How BIOSCREEN Estimates Actual Plume Mass for Biodegradation Models

If the mass of organics in the 5x10 plume array is within 50% to 150% of the mass of organics

that have left the source (see box above), then two values are calculated:

% Biodegraded, 1st order decay = (Plume Mass, 1st order decay) * 100 / (Plume mass, no

biodeg)

% Biodegraded, inst. react. = (Plume Mass, inst. react) * 100 / (Plume mass, no biodeg)

These percentages are multiplied against the Plume Mass if No Biodegradation Value (first

box) to estimate the actual plume mass for the two biodegradation models. If the No

Degradation model has been selected, there is no biodegradation, and the Actual Plume Mass(second box) will equal the Plume Mass if No Biodegradation (first box).


35

If BIOSCREEN Says “Can’t Calc”

If the mass of organics in the plume does not fall within 50% to 150% of the mass of organics

that have left the source (first box), then the model concludes that the modeled area (see

Input Screen, Section 5: General Data) is not sized correctly to capture enough mass in the

5X10 array and writes “Can't Calc” in the box. The user is encouraged to adjust the modeled

length and width to capture most of the No Degradation plume in the 5x10 array. In

addition, sometimes source conditions with variable concentrations and widths (see input

screens) can make it difficult to accurately capture the plume mass. If the user has problems

obtaining a mass balance even after changing the modeled area, change the source term to a

single source zone (instead of 3 or 5 zones) to improve the accuracy of the mass balance.

If problems still exist, ensure that the vertical dispersivity term (Section 2 on the Input

Screen) is set to 0 (the default value). The mass balance calculations are less accurate for

three-dimensional simulations.

Plume Mass Removed by Biodegradation (kg)

An estimate of the mass of contaminants that are biodegraded is provided in BIOSCREEN.

The model subtracts the Actual Plume Mass (second box) from the Plume Mass if No

Biodegradation (first box). For the No Degradation model, the first box equals the second

box, and Plume Mass Removed by Biodeg is zero. For the other two cases, the 2 boxes will

differ, and the amount of biodegradation will be calculated. The value beneath the third

box shows the % of organics that have left the source and have been biodegraded.

Change in Electron Acceptor/Byproduct Masses (kg)

BIOSCREEN uses the Plume Mass Removed by Biodegradation to back-calculate the amount

of measurable electron acceptors consumed and the amount of measurable metabolic by-

products that have been produced.

For example, the amount of oxygen consumed is calculated by:

Oxygen Consumed (kg) = (Plume Mass Removed by Biodeg) * (Delta O2/Util. Fact.)

( Biodeg. Capacity)

(see Biodegradation Capacity section to see how this term is calculated)

Note that the total sum of consumed electron acceptors does not equal the Plume Mass

Removed by Biodegradation. This is because the stoichiometry of the biodegradation

reactions do not represent a 1:1 relationship between the mass of hydrocarbon and electron

acceptor consumed (see Utilization Factor section).

Original Mass in Source (kg)

Equal to the Soluble Mass in NAPL and Soil entered by the user on the Input Screen. If the

user has selected an “Infinite” mass to simulate a non-declining source, this box will show

“Infinite.”

Mass in Source Now (kg)

The amount of mass remaining in the source zone at the end of the simulation period is

calculated and displayed in this box. This calculation is performed as follows:

(Mass in the Source Now) =

(Original Mass in Source) - (Actual Plume Mass + Plume Mass Removed by Biodeg)


36

Current Volume of Groundwater in Plume (ac-ft)

If the mass of organics in the plume falls within 50% to 150% of the mass of organics that

have left the source (first box), then the model concludes the modeled area (see Input Screen,

Section 5: General Data) is appropriately sized to estimate the volume of the plume. In this

case BIOSCREEN counts the number of cells in the 5 x 10 array with concentration values

greater than 0, and multiplies this by the volume of groundwater in each cell (length * width

* source thickness * porosity).

If the user wishes to estimate the volume of the plume above a certain target level, enter the

target level in the appropriate box and press the appropriate model to display the result

(No Degradation, 1st Order Decay, or Instantaneous Reaction).

Note that the model does not account for the effects of any vertical dispersion.

Flowrate of Water Through Source Zone (ac-ft/yr)

Using the Darcy velocity, the source thickness, and the source width, BIOSCREEN calculates

the rate that clean groundwater moves through the source zone where it will pick up

dissolved hydrocarbons. Note that the groundwater Darcy velocity is equal to the

groundwater seepage velocity multiplied by porosity.


37

BIOSCREEN TROUBLESHOOTING TIPS

Minimum System Requirements

The BIOSCREEN model requires a computer system capable of running Microsoft Excel 5.0 for

Windows. Because of the volume of calculations required to process the numerical data

generated by the model, GSI recommends running the model on a system equipped with a 486 DX

or higher processor running at 66 MHz or faster. A minimum of 8 Megabytes of system memory

(RAM) is strongly recommended.

The model's input and output screens are optimized for display at a monitor resolution of

640x480 (Standard VGA). If you are using a higher resolution, for example 800x600 or 1024x768,

see Changing the Model's Display.

For best results, Start Excel and Load the BSCREEN.XLS file from the File / Open menu.

Spreadsheet-Related Problems

The buttons won’t work: BIOSCREEN is built in the Excel spreadsheet environment, and to

enter data one must click anywhere outside the cell where you just entered data. If you can see

the numbers you just entered in the data entry part of Excel above the spreadsheet, the data has

not yet been entered. Click on another cell to enter the data.

#### is displayed in a number box: The cell format is not compatible with the value, (e.g. the

number is too big to fit into the window). To fix this, select the cell, pull down the format menu,

select “Cells” and click on the “Number” tab. Change the format of the cell until the value is

visible. If the values still cannot be read, select the format menu, select “Cells” and click on the

“Font” tab. Reduce the font size until the value can be read.

#DIV/0! is displayed in a number box: The most common cause of this problem is that some

input data are missing. In some cases, entering a zero in a box will cause this problem. Double

check to make certain that all of the input cells required for your run have data. Note that for

vertical dispersivity, BIOSCREEN will convert a “0” into the data entry cell into a very low

number (1x10 -99) to avoid #DIV/0! errors.

There once were formulas in some of the boxes on the input screen, but they were accidentallyoverwritten: Click on the “Restore Formulas for Vs, Dispersivities, R, and lambda” button on

the bottom right-hand side of the input screen. Note that this button will also restore the

formulas that make the Source Width and Source Concentrations for source zones 4 and 5 equal

to source zones 2 and 1, respectively.

The graphs seem to move around and change size: This is a feature of Excel. When graph scales

are altered to accommodate different plotted data, the physical size of the graphs will change

slightly, sometimes resulting in a graph that spreads out over the fixed axis legends. You can

manually resize the graph to make it look nice again by double-clicking on the graph and

resizing it (refer to the Excel User’s Manual).

Common Error Messages

Unable to Load Help File: The most common error message encountered with BIOSCREEN is

the message "Unable to Open Help File" after clicking on a Help button. Depending on the

version of Windows you are using, you may get an Excel Dialog Box, a Windows Dialog Box, or


38

you may see Windows Help load and display the error. This problem is related to the ease

with which the Windows Help Engine can find the data file, BIOSCRN.HLP. Here are some

suggestions (in decreasing order of preference) for helping WinHelp find it:

• If you are fortunate enough to be asked to find the requested datafile, do so. It's

called BIOSCRN.HLP, and it was installed in the same directory/folder as the

BIOSCRN.XLS file.

• Use the File/Open menus from within Excel instead of double-clicking on the

filename or Program Manager icon to open the BIOSCRN.XLS file. This sets the

"current directory" to the directory containing the Excel file you just opened.

• Change the WinHelp call in the VB Module to "hard code" the directory

information. That way, the file name and its full path will be explicitly passed to

WinHelp. Hints for doing this are in the VBA module. Select the Macro Module tab

and search for the text "Helpfile".

• As a last resort, you can add the BIOSCREEN directory to your path (located in your

AUTOEXEC.BAT file), and this problem will be cured. You will have to reboot your

machine, however, to make this work

The BIOSCREEN system was designed to be used on a PC with Windows configured to a

standard VGA resolution of 640x480 pixels. If you are using a larger monitor and your video

resolution is set to 800x600 pixels or greater, you will need to change the zoom factor in the

Visual Basic code.

In the first three lines in the Macro Module of the BIOSCREEN spreadsheet, change the

number after the equals sign in the following line:

Const ZoomValue = 65

If your display resolution is standard VGA (640x480), use 65 for the zoom value. If your

resolution is 800x600, use a zoom value of 82. If your resolution is not 640x480 or 800x600, if your

video performance is seriously degraded, or if you experience display problems, you may need to

change your video resolution (see the on-line help for Windows Setup or consult your Windows

installation manuals) and experiment with other values for ZoomValue.


39

REFERENCES

American Society for Testing and Materials, 1995, "Standard Guide for Risk-Based Corrective ActionApplied at Petroleum Release Sites," ASTM E-1739-95, Philadelphia, PA.

Bedient, P. B., H.S. Rifai, and C.J. Newell, 1994. Groundwater Contamination: Transport and Remediation,Prentice-Hall.

Borden, R. C., P. B. Bedient, M. D. Lee, C. H. Ward and J. T. Wilson, 1986. "Transport of DissolvedHydrocarbons Influenced by Oxygen Limited Biodegradation: 2. Field Application," Water Resour. Res.22:1983-1990.

Connor, J.A., C.J. Newell, J.P. Nevin, and H.S. Rifai, 1994. "Guidelines for Use of Groundwater SpreadsheetModels in Risk-Based Corrective Action Design," National Ground Water Association, Proceedings ofthe Petroleum Hydrocarbons and Organic Chemicals in Ground Water Conference, Houston, Texas,November 1994, pp. 43-55.

Connor, J.A., J. P. Nevin, R. T. Fisher, R. L. Bowers, and C. J. Newell, 1995a. RBCA Spreadsheet System andModeling Guidelines Version 1.0, Groundwater Services, Inc., Houston, Texas.

Connor, J.A., J. P. Nevin, M. Malander, C. Stanley, and G. DeVaull, 1995b. Tier 2 Guidance Manual for Risk-Based Corrective Action, Groundwater Services, Inc., Houston, Texas.

Davis J.W., N.J. Kliker, and C.L. Carpenter, 1994, Natural Biological Attenuation of Benzene in GroundWater Beneath a Manufacturing Facility, Ground Water, Vol. 32, No. 2., pg 215-226.

Domenico, P.A. 1987. An Analytical Model for Multidimensional Transport of a Decaying ContaminantSpecies. Journal of Hydrology, 91 (1987) 49-58.

Domenico, P.A. and F. W. Schwartz, 1990. Physical and Chemical Hydrogeology, Wiley, New York, NY.

Gelhar, L.W., Montoglou, A., Welty, C., and Rehfeldt, K.R., 1985. "A Review of Field Scale Physical SoluteTransport Processes in Saturated and Unsaturated Porous Media," Final Proj. Report., EPRI EA-4190,Electric Power Research Institute, Palo Alto, Ca.

Gelhar, L.W., C. Welty, and K.R. Rehfeldt, 1992. “A Critical Review of Data on Field-Scale Dispersion inAquifers.” Water Resources Research, Vol. 28, No. 7, pg 1955-1974.

Howard, P. H., R. S. Boethling, W. F. Jarvis, W. M. Meylan, and E. M. Michalenko, 1991. Handbook ofEnvironmental Degradation Rates, Lewis Publishers, Inc., Chelsea, MI.

Lee, M.D. V.W. Jamison, and R.L. Raymond, 1987, “Applicability of In-Situ Bioreclamation as a RemedialAction Alternative,” in Proceedings of the Petroleum Hydrocarbons and Organic Chemicals in GroundWater Conference, Houston, Texas, November 1987, pp. 167-185.

Lovely, D. Personal Communication. 1995.

Mercer, J. W., and R. M. Cohen, 1990. “A Review of Immiscible Fluids in the Subsurface: Properties, Models,Characterization and Remediation,” Journal of Contaminant Hydrology, 6 (1990) 107-163.

Newell, C. J., R. L. Bowers, and H. S. Rifai, 1994. "Impact of Non-Aqueous Phase Liquids (NAPLs) onGroundwater Remediation," American Chemical Society Symposium on Multimedia Pollutant TransportModels, Denver, Colorado, August 1994.

Newell, C.J., J.W. Winters, H.S. Rifai, R.N. Miller, J. Gonzales, T.H. Wiedemeier, 1995. “Modeling IntrinsicRemediation With Multiple Electron Acceptors: Results From Seven Sites,” National Ground WaterAssociation, Proceedings of the Petroleum Hydrocarbons and Organic Chemicals in Ground WaterConference, Houston, Texas, November 1995, pp. 33-48.

Rifai, H.S., personal communication, 1994.

Rifai, H. S. and P.B. Bedient, 1990, "Comparison of Biodegradation Kinetics With an Instantaneous ReactionModel for Groundwater," Water Resources Research, Vol. 26, No. 4, pp. 637-645, April 1990.

Rifai, H. S., P. B. Bedient, R. C. Borden, and J. F. Haasbeek, 1987, BIOPLUME II - Computer Model of Two-Dimensional Transport under the Influence of Oxygen Limited Biodegradation in Ground Water, User'sManual, Version 1.0, Rice University, Houston, TX, 1987.

Rifai, H. S., P. B. Bedient, J. T. Wilson, K. M. Miller, and J. M. Armstrong, 1988, "Biodegradation Modeling atAviation Fuel Spill Site," J. Environ. Engineering 114(5):1007-1029, 1988.

Rifai, H. S., G. P. Long, P.B. Bedient, 1991. "Modeling Bioremediation: Theory and Field Application,"Proceedings, In Situ Bioreclamation, Applications and Investigations for Hydrocarbon andContaminated Site Remediation, Ed. by R. E. Hinchee and R. F. Olfenbuttel, Battelle Memorial Institute,Butterworth-Heinemann, Boston, March 1991.

Rifai, H. S., C. J. Newell, R. N. Miller, S. Taffinder, and M. Rounsavill, 1995. “Simulation of NaturalAttenuation with Multiple Electron Acceptors,” Intrinsic Remediation, Edited by R. Hinchee, J. Wilson,and D. Downey, Battelle Press, Columbus, Ohio, p 53-65.

Pickens, J.F., and G.E. Grisak,1981. “Scale-Dependent Dispersion in a Stratified Granular Aquifer,” J. WaterResources Research, Vol. 17, No. 4, pp 1191-1211.


40

REFERENCES (Cont’d)

Smith, L. and S.W. Wheatcraft, 1993. “Groundwater Flow” in Handbook of Hydrology, David Maidment,Editor, McGraw-Hill, New York.

Snoeynik, V., and D. Jenkins, 1980. Water Chemistry. John Wiley and Sons, New York, New York.

U.S. Environmental Protection Agency, 1986, Background Document for the Ground-Water ScreeningProcedure to Support 40 CFR Part 269 --- Land Disposal. EPA/530-SW-86-047, January 1986.

Walton, W.C., 1988. Practical Aspects of Groundwater Modeling: National Water Well Association,Worthington, Ohio.

Wiedemeier, T.H., M. A. Swanson, J. T. Wilson, D. H. Kampbell, and R. N. Miller, 1995. “Patterns of IntrinsicBioremediation at Two United States Air Force Bases”, Proceedings of the 1995 Battelle Conference onBioremediation, San Diego, California.

Wiedemeier, T.H., R.N. Miller, J.T. Wilson, and D.H. Kampbell, 1995. “Significance of Anaerobic Processesfor the Intrinsic Bioremediation of Fuel Hydrocarbons”, 1995. National Ground Water Association,Proceedings of the Petroleum Hydrocarbons and Organic Chemicals in Ground Water Conference,Houston, Texas, November 1995.

Wiedemeier, T. H., Wilson, J. T., Kampbell, D. H, Miller, R. N., and Hansen, J.E., 1995. "Technical Protocol forImplementing Intrinsic Remediation With Long-Term Monitoring for Natural Attenuation of FuelContamination Dissolved in Groundwater (Revision 0)", Air Force Center for Environmental Excellence,April, 1995.

Wilson J. T., 1994. Presentation at Symposium on Intrinsic Bioremediation of Ground Water, Denver,Colorado, August 1-Sept. 1, 1994, EPA 600/R-94-162.

Wilson, J. T., J. F. McNabb, J. W. Cochran, T. H. Wang, M. B. Tomson, and P. B. Bedient, 1985. “Influence OfMicrobial Adaptation On The Fate Of Organic Pollutants In Groundwater,” Environmental Toxicologyand Chemistry, v. 4, p. 721-726.

Wilson, J. T., 1996. Personal communication. He may be reached at the Subsurface Protection andRemediation Division of the National Risk Management Laboratory, Ada, Oklahoma.

Xu, Moujin and Y. Eckstein, 1995, “Use of Weighted Least-Squares Method in Evaluation of the RelationshipBetween Dispersivity and Scale,” Journal of Ground Water, Vol. 33, No. 6, pp 905-908.


41

APPENDIX A.1 DOMENICO ANALYTICAL MODEL

The Domenico (1987) analytical model, used by BIOSCREEN, is designed for the multidimen-

sional transport of a decaying contaminant species. The model equation, boundary conditions,

assumptions, and limitations are discussed below.

Domenico Model with Instantaneous Reaction Superposition Algorithm

C (x)Csource

Plume Source

Z

wS

Groundwater

Flow Direction

Dispersivity

X

αz

α y

αx

C x y o t

Co BC

xv

erfcx vt v

vt

erfy Y

xerf

y Y

xx

x

x

y

, , ,exp /

/

( )

/ /

/

/

/

/

( )+( )

= − +( )( )

− +( )( )

+( )( )

− −( )

18 2

1 1 4

1 4

2

2

2

2

1 2

1 2

1 2

1 2

αλα

λα

α

α 22

2 2

1 2

1 2 1 2

α

α α

y

z z

x

erfZ

xerf

Z

xBC

( )

( )( )

− −( )( )

−

/

/ /

where: vK i

Re

= ⋅θ

BCC ea

UFn

n

= Σ ( )

Definitions

BC Biodegradation capacity (mg/L)

C(x,y,z,t) Concentration at distance x downstream of

source and distance y off centerline of plume at

time t (mg/L)

Cs Concentration in Source Zone (mg/L)

Co Concentration in Source Zone at t=0 (mg/L)

x Distance downgradient of source (ft)

y Distance from plume centerline of source (ft)

z Distance from surface to measurement point

(assumed to be 0; concentration is always

assumed to be at top of water table).

C(ea)n Concentration of electron acceptor n in

groundwater (mg/L)

UFn Utilization factor for electron acceptor n (i.e., mass ratio

of electron acceptor to hydrocarbon consumed in

biodegradation reaction)

ÿ x Longitudinal groundwater dispersivity (ft)

ÿy Transverse groundwater dispersivity (ft)

ÿ z Vertical groundwater dispersivity (ft)

ÿe Effective Soil Porosity

ÿ First-Order Degradation Rate (day -1)

ÿ Groundwater Seepage Velocity (ft/yr)

K Hydraulic Conductivity (ft/yr)

R Constituent retardation factor

i Hydraulic Gradient (cm/cm)

Y Source Width (ft)

Z Source Depth (ft)

The initial conditions are:

1) c(x, y, z, 0) = 0 (Initial concentration = 0 for x, y, z, > 0)

2) c(0, Y, Z, 0) = C0 (Source concentration for each vertical plane source = C0 at time 0)

The key assumptions in the model are:

1) The aquifer and flow field are homogenenous and isotropic.

2) The groundwater velocity is fast enough that molecular diffusion in the dispersion

terms can be ignored (may not be appropriate for simulation of transport through

clays).

3) Adsorption is a reversible process represented by a linear isotherm.


42

The key limitations to the model are:

1) The model should not be applied where pumping systems create a complicated flow

field.

2) The model should not be applied where vertical flow gradients affect contaminant

transport.

3) The model should not be applied where hydrogeologic conditions change

dramatically over the simulation domain.

The most important modifications to the original Domenico model are:

1) The addition of “layer cake” source terms where three Domenico models are

superimposed one on top of another to yield the 5-source term used in BIOSCREEN

(see Connor et al., 1994; and the Source Width description in the BIOSCREEN Data

Entry Section).

2) Addition of the instantaneous reaction term using the superposition algorithm (see

Appendix A.2, below). For the instantaneous reaction assumption, the source

concentration is assumed to be an “effective source concentration” (Coe) equal to the

observed concentration in the source zone plus the biodegradation capacity (see

“Source Concentration” on the BIOSCREEN Data Entry section).


43

APPENDIX A.2 INSTANTANEOUS REACTION - SUPERPOSITION ALGORITHM

Early biodegradation research focused on the role of dissolved oxygen in controlling the rate of

biodegradation in the subsurface (Borden e t a l ., 1986; Lee et a l , 1987). Because microbial

biodegradation kinetics are relatively fast in comparison to the rate of oxygen transport in the

groundwater flow system, Borden demonstrated that the biodegradation process can be

simulated as an instantaneous reaction between the organic contaminant and oxygen. This

simplifying assumption was incorporated into the BIOPLUME I numerical model which

calculated organic mass loss by superposition of background oxygen concentrations onto the

organic contaminant plume. In BIOPLUME II, a dual-particle mover procedure was

incorporated to more accurately simulate the separate transport of oxygen and organic

contaminants within the subsurface (Rifai et al, 1987; Rifai, et al, 1988).

In most analytical modeling applications, contaminant biodegradation is estimated using a

first-order decay equation with the biodecay half-life values determined from research

literature or site data. However, by ignoring oxygen limitation effects such first-order

expressions can significantly overestimate the rate and degree of biodegradation, particularly

within low-flow regimes where the rate of oxygen exchange in a groundwater plume is very

slow (Rifai, 1994). As a more accurate method of analysis, Newell recommended incorporation

of the concept of oxygen superposition into an analytical model (Connor et al., 1994) in a manner

similar to that employed in the original BIOPLUME model (Borden e t a l . 1986). By this

method, contaminant mass concentrations at any location and time within the flow field are

corrected by subtracting 1 mg/L organic mass for each 3 mg/L of background oxygen, in accordance

with the instantaneous reaction assumption. Borden et a l . (1986) concluded this simple

superposition technique was an exact replacement for more sophisticated oxygen-limited

models, as long as the oxygen and the hydrocarbon had the same transport rates (e.g.,

retardation factor, R = 1).

In their original work, Borden et al . (1986) noted that for highly sorptive contaminants the

oxygen-superposition method might erroneously characterize biodegradation due to the

differing transport rates of dissolved oxygen and the organic contaminant within the aquifer

matrix. However, as demonstrated by Connor et al . (1994), the oxygen superposition method

and BIOPLUME II (dual particle transport) are in reasonable agreement for contaminant

retardation factors as high as 6. Therefore, the superposition method can be employed as a

reasonable approximation in BIOSCREEN regardless of contaminant sorption characteristics.

BIOSCREEN employs the same superposition approach for all of the aerobic and anaerobic

biodegradation reactions (based on evaluation of O2 , NO 3, SO4, Fe2+, and CH 4). Based on work

reported by Newell e t a l . (1995), the anaerobic reactions (nitrate, ferric iron, and sulfate

reduction and methanogenesis) are amenable to simulation using the instantaneous reaction

assumption. The general approach is presented below:


44

STEP 1:

STEP 2:

STEP 3:

Run model with no decay

(but with source zoneconcentration equal tomeasured source zoneconcentration +biodegradation capacity BC )

Subtract BiodegradationCapacity (BC) from NoDecay Concentrations

Predict biodegraded plumeconcentrations assumingInstantaneous ReactionAssumption

Cno decay

– BC

= Cinst

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

BCBC

C0 = Cmeasured + BC

Based on the biodegradation capacity of electron acceptors present in the groundwater system,

this algorithm will correct the non-decayed groundwater plume concentrations predicted by the

Domenico model (Appendix A.1) for the effects of organic constituent biodegradation.

To summarize:

1) The original BIOPLUME model (Borden et al. 1986) used a superposition method to simulate

the fast or “instantaneous” reaction of dissolved hydrocarbons with dissolved oxygen in

groundwater.

2) Borden et al. (1986) reported that this version of BIOPLUME was mathematically exact for

the case where the retardation factor of the contaminant was 1.0.

3) Rifai and Bedient (1990) developed the BIOPLUME II model with a dual-particle tracking

routine that expanded the original BIOPLUME model to handle contaminants with

retardation factors other than 1.0, in addition to other improvements.

4) Connor et al. (1994) compared the superposition method with the more sophisticated

BIOPLUME II model and determined that the two approaches yielded very similar results

for readily biodegradable contaminants with retardation factors between 1.0 and 6.0.

5) BIOSCREEN was developed using the superposition approach to simulate the

“instantaneous” reaction of aerobic and anaerobic reactions in groundwater. The biodegra-

dation term in BIOSCREEN is mathematically identical to the approach used in the

original BIOPLUME model. This mathematical approach (superposition) matches the more

sophisticated BIOPLUME II model very closely for readily biodegradable contaminant

retardation factors of up to 6.0. BIOSCREEN simulations using the instantaneous reaction

assumption at sites with retardation factors greater than 6.0 should be performed with

caution and verified using a more sophisticated model such as BIOPLUME III.


45

APPENDIX A.3 DERIVATION OF SOURCE HALF-LIFE

Purpose: Determine the source half-life relationship used in BIOSCREEN (see Source

Half-Life discussion in BIOSCREEN Data Entry Section, pg 30).

Given: 1) There is a finite amount of soluble organic compounds in source zone (the

area with contaminated soils and either free-phase or residual NAPL.

2) These organics dissolve slowly as fresh groundwater passes through source

zone. Assume the change in mass due to dissolution can be approximated as

a first order process:

M(t) = M 0 e-k s t (1)

Procedure: 1) Calculate initial mass of dissolvable organics in source zone, M0 0

2) Determine initial source concentration from monitoring well data, C0 0

3) Apply conservation of mass to a control surface containing source zone.

4) Set the expressions for mass at time t ≥ 0 based on dissolution and

conservation of mass equal to each other and solve for an expression

describing the concentration at time t ≥ 0.

5) Apply initial conditions for concentration at time t = 0 and solve for the first

order decay constant, ks. .

Assumptions: 1) Groundwater flowrate is constant, Q(t)=Q0 0

2) Groundwater flowing through the source zone is free of organic compounds.

This implies that no mass is added to the system, only dissolution occurs.

Calculations: 1) Calculate initial mass of dissolved/soluble organic compound, M0 by using

procedure described under “Soluble Mass in NAPL, Soil” page in

BIOSCREEN Data Input section.

2) Determine initial concentration, C0 of organic compound in groundwater

leaving the source zone. This may be a spatial average, maximum value, or

other value representative of the groundwater concentration leaving the

source area. (Note that for the instantaneous reaction assumption, C0 equals

the concentration observed in monitoring wells plus the biodegradation

capacity to account for rapid biodegradation reactions in the source zone.

See “Soluble Mass in NAPL, Soil” page in BIOSCREEN Data Input section).

C(t=0) = C0 (2)

3) Apply conservation of mass to a control surface that contains the source

zone. The mass present in the source zone at time t ÿ 0 is the initial mass

minus the change in mass.

(3)


46

DERIVATION OF SOURCE HALF-LIFE, Cont’d

Applying the assumptions equation (3) simplifies to

(4)

4) Set the two expressions for mass of organic compound in the source zone at

time t ÿ 0 (equations (1) and (4)) equal to each other and solve for an

expression describing the concentration leaving the source zone.

(5)

d

dtQ0 C(t)dt = M0 − M0e −kst

t∫[ ] (6)

Q0 C(t) = ks M0 e-kst (7)

C(t) =ksM

0

Q0

e−kst (8)

5) Apply the initial condition for concentration leaving the source zone at

time t=0, eqn (2) to the expression for C(t), eqn (8) and solve for the first

order decay coefficient, k s

C0 =ksM0

Q0 (9)

ks =Q0C0

M0 (11)

Summary: The decay coefficient for the source zone in BIOSCREEN is:

k s =Q0C0

M0

The expression for mass at any time t ≥ 0 is:

M(t)= M 0 e-kst

Noting that the change in source concentration is directly related to the change

in source mass, the expression for source zone concentration any time t ≥ 0 is:

C(t)= C 0 e-kst

Acknowledgments: Original derivation developed by C. Newell. Detailed derivation developed by XiaomingLiu, Anthony Holder, and Thomas Reeves.


47

APPENDIX A.4 DISPERSIVITY ESTIMATES

Dispersion refers to the process whereby a plume will spread out in a longitudinal direction

(along the direction of groundwater flow), transversely (perpendicular to groundwater flow),

and vertically downwards due to mechanical mixing in the aquifer and chemical diffusion.

Selection of dispersivity values is a difficult process, given the impracticability of measuring

dispersion in the field. However, dispersivity data from over 50 sites has been compiled by

Gelhar et al. (1992) (see figures A.1 and A.2, next page).

The empirical data indicates that longitudinal dispersivity, in units of length, is related to

scale (distance between source and measurement point; the plume length; Lp in BIOSCREEN).

Gelhar et al. (1992) indicate 1) there is a considerable range of dispersivity values at any given

scale (on the order of 2 - 3 orders of magnitude), 2) suggest using values at the low end of the

range of possible dispersivity values, and 3) caution against using a single relationship between

scale and dispersivity to estimate dispersivity. However, most modeling studies do start with

such simple relationships, and BIOSCREEN is programmed with some commonly used

relationships representative of typical and low-end dispersivities:

• Longitudinal Dispersivity

Alpha x = 3.28 0.83 log

Lp⋅ ⋅

10 3 28

2 414

.

.


(Lp in ft)

• Transverse Dispersivity

Alpha y = 0.10 alpha x (Based on high reliability

points from Gelhar et al., 1992)

• Vertical Dispersivity

Alpha z = very low (i.e. 1 x e-99 ft) (Based on conservative estimate

Other commonly used relationships include:

Alpha x = 0.1 Lp (Pickens and Grisak, 1981)

Alpha y = 0.33 alpha x (ASTM, 1995) (EPA, 1986)

Alpha z = 0.05 alpha x (ASTM, 1995)

Alpha z = 0.025 alpha x to 0.1 alpha x (EPA, 1986)

The BIOSCREEN input s creen includes Excel formulas to estimate dispersivities from s cale.

BIOSCREEN uses t he Xu and Eckstein (1995) algorithm for estimating longitudinal

dispersivities because 1) it provides lower range estimates of dispersivity, especially for large

values of Lp, and 2) it was developed after weighting the reliability of the various field data

compiled b y Gelhar et al .. (1992) (see Figure A.1). BIOSCREEN also employs low-end

estimates for transverse and vertical dispersivity estimates (0.10 alpha x and 0 , respectively)

because: 1) these relationships better fit observed field data reported by Gelhar et al. to have

high reliability (see Figure A.2), 2) Gelhar et al. recommend use of values in the lower range o f

the observed data, and 3) better results were realized when calibrating BIOSCREEN to actual


48

field sites using lower dispersivities. The user can override these formulas by directly entering

dispersivity values in the input screen cell.

Note that the Domenico model and BIOSCREEN are not formulated to simulate the effects of

chemical diffusion. Therefore, contaminant transport through very slow hydrogeologic regimes

(e.g., clays and slurry walls) should probably not be modeled using BIOSCREEN unless the

effects of chemical diffusion are proven to be insignificant. Domenico and Schwartz (1990)

indicate that chemical diffusion is small for Peclet numbers (seepage velocity times median

pore size divided by the bulk diffusion coefficient) greater than 100.

10-1 10 0 101 10 2 10 3 104

Scale (m)

10 5 610

104

10 3

10 2

10 1

10 0

10-1

10-2

10-3

RELIABILITY

Longitudinal Dispersivity= 10% of scale

Data Source: Gelhar et al., 1992

(Pickens and Grisak, 1981)


Longitudinal Dispersivity= 0.83 [Log (scale)]2.41410

Low

Intermediate

High

Lo

ng

itu

din

al d

isp

ersi

vity

(m

)

Figure A.1. Longitudinal dispersivity vs. scale data reported by Gelhar et al. (1992).Data includes Gelhar’s reanalysis of several dispersivity studies. Size of circlerepresents general reliability of dispersivity estimates. Location of 10% of scale linearrelationship plotted as dashed line (Pickens and Grisak, 1981). Xu and Eckstein’sregression (used in BIOSCREEN) shown as solid line. Shaded area defines ± 1 orderof magnitude from the Xu and Eckstein regression line and represents general rangeof acceptable values for dispersivity estimates. Note that BIOSCREEN defines scaleas Lp, the plume length or distance to measurement point in ft, and employs the Xuand Eckstein algorithm with a conversion factor.


49

Scale (m)

101

100

10-1

10 -2

10-3

10-1 100 101 102 103 104 105

Scale (m)

Transverse Dispersivity = 10% of alpha x

10-3

10-2

10-1

100

101

10 -1 100 101 102 103 104 105

Data Source: Gelhar et al., 1992 Data Source: Gelhar et al., 1992

LowIntermediateHigh

LowIntermediateHigh

Figure A.2 Ratio of transverse dispersivity and vertical dispersivity to longitudinal dispersivity data vs. scalereported by Gelhar et al. (1992). Data includes Gelhar’s reanalysis of several dispersivity studies. Size of symbolrepresents general reliability of dispersivity estimates. Location of transverse dispersivity relationship used inBIOSCREEN is plotted as dashed line.


50

APPENDIX A.5 ACKNOWLEDGMENTS

BIOSCREEN was developed for the Air Force Center for Environmental Excellence, Brooks

AFB, San Antonio, Texas by Groundwater Services, Inc.

AFCEE Technology TransferDivision Chiefs:

Lt. Col. Ross Miller

Mr. Marty Faile

AFCEE Project Officer: Mr. Jim Gonzales

BIOSCREEN Developers: Charles J. Newell, Ph.D., P.E. and R. Kevin McLeod

Groundwater Services, Inc. phone: 713 663-66005252 Westchester, Suite 270 fax: 713 663-6546Houston, Texas 77005 cjnewell@gsi-net. com

rkmcleod@gsi-net. com

BIOSCREEN Manual: Charles J. Newell, Ph.D., P.E.Groundwater Services, Inc.

Contributors to BIOSCREEN: R. Todd Fisher, Xiaoming Liu, Tariq Kahn, Mat Ballard, JackieWinters, Phil Bedient, Anthony Holder, Hanadi Rifai

BIOSCREEN Review Team: Gilberto Alvarez USEPA Region V, Chicago, Ill.

Mike Barden Wisconsin Dept. of Natural Resources

James Barksdale US EPA Region IV, Atlanta, GA.

Kathy Grindstaff Indiana Dept. of EnvironmentalManagement (IDEM)

Robin Jenkins Utah DEQ, Lust Program

Tim R. Larson Florida Dept. of EnvironmentalProtection

Luanne Vanderpool US EPA Region V, Chicago, Ill.

Dr. Jim Weaver US EPA National Risk ManagementResearch Laboratory

Todd Wiedemeier

Todd Herrington

Matt Swanson

Kinzie Gordon

Parsons Engineering Science, Inc.

Joe R. Williams US EPA National Risk ManagementResearch Laboratory

Dr. John Wilson US EPA National Risk ManagementResearch Laboratory

Ying Ouyang

Rashid IslamComputer Data Systems

The Air Force Center for Environmental Excellence is distributing BIOSCREEN via:

EPA Center for Subsurface ModelingSupport (CSMoS)NRMRL/SPRD

P.O. Box 1198Ada, Oklahoma 74821-1198

• Phone: (405) 436-8594

• Fax: (405) 436-8718

• Bulletin Board: (405) 436-8506 (14,400 baud-8 bits -1 stop bit -no parity).

• Web: http://www.epa.gov/ada/kerrlab.html(Electronic manuals will be in .pdf format; mustdownload Adobe Acrobat Reader to read andprint pdf files.)

http://www.epa.gov/ada/kerrlab.htm

http://www.adobe.com/


51

APPENDIX A.6 BIOSCREEN EXAMPLES

Example 1: SWMU 66, Keesler AFB, Mississippi

• Input Data

• Fig. 1 Source Map

• BIOSCREEN Modeling Summary

• Fig. 2 BIOSCREEN Input Data

• Fig. 3 BIOSCREEN Centerline Output

• Fig. 4 BIOSCREEN Array Output

Example 2: UST Site 870, Hill AFB, Utah

• Input Data







52

BIOSCREEN EXAMPLE 1

Keesler Air Force Base, SWMU 66, Mississippi

DATA TYPE Parameter Value Source of Data

Hydrogeology • Hydraulic Conductivity:• Hydraulic Gradient:• Porosity:

1.1 x 10-2 (cm/sec)0.003 (ft/ft)0.3

• Slug-tests results• Static water level

measurements• Estimated

Dispersion Original:

• Longitudinal Dispersivity:• Transverse Dispersivity:• Vertical Dispersivity:

After Calibration:


13.3 (ft)1.3 (ft)0 (ft)

32.5 (ft)3.25 (ft)0 (ft)

• Based on estimated plumelength of 280 ft andXu/Eckstein relationship

• Based on calibration toplume length (Note this iswell within the observedrange for long. dispersivity;see Fig. A.1 in AppendixA..3. Remember to convertfrom feet to meters beforeusing the chart).

Adsorption • Retardation Factor:

• Soil Bulk Density ρb:• foc:• Koc:

1.0

1.7 (kg/L)0.0057%B: 38 T: 135E: 95 X: 240

• Calculated fromR = 1+Koc x foc x ρb/n

• Estimated• Lab analysis• Literature - use Koc = 38

Biodegradation Electron Acceptor:Background Conc. (mg/L):Minimum Conc. (mg/L):Change in Conc. (mg/L):

Electron Acceptor:Max. Conc. (mg/L):Avg. Conc. (mg/L):

O2 NO3 SO4 2.05 0.7 26.2- 0.4 - 0 - 3.8 1.65 0.7 22.4

Fe CH4 36.1 7.4 16.6 6.6

Note: Boxed values areBIOSCREEN input values.

• Based on March 1995groundwater samplingprogram conducted byGroundwater Services, Inc.

General • Modeled Area Length:• Modeled Area Width:• Simulation Time:

320 (ft)200 (ft)6 (yrs)

• Based on area of affectedgroundwater plume

• Steady-state flow

Source Data • Source Thickness:• Source Concentration:

10 (ft)(See Figure 1)

• Based on geologic logs andlumped BTEX monitoringdata

Actual Data Distance From Source (ft):BTEX Conc. (mg/L):

30 60 180 280 5.0 1.0 0.5 0.001

• Based on observedconcentrations at site

OUTPUT Centerline Concentration: See Figure 3

Array Concentration: See Figure 4


53

SWMU 66 Site, Keesler AFB, Mississippi

LEGEND

FIGURE 1

MW9-50.001

T-210.210

MW9-4ND

MW9-6ND

MW9-2ND

0

MW9-10.003

T-160.596

10

T-7ND

T-5ND

T-3ND

T-1ND

T-80.793

Monitoring well locationTemporary cone penetrometer (CPT) piezometer locationTotal BTEX detected in groundwater sample, mg/L0.003

No BTEX detectedND

Zone

321

Width (ft)Actual Source Conc.

in 1995 (mg/L)

143020

12

BTEX concentration isopleth, mg/L, March 1995

SCALE (ft.)

0 40 80

BIOSCREEN SOURCE ZONEASSUMPTIONS

AffectedSoil Zone

AffectedGroundwater

Zone

1

2

3

Groundwater Flow Direction

T-1314.1

Source conc. based on Geometric mean betweenconcentration isopleth contours.

Adjusted Model SourceConc. in 1989 (mg/L)

13.72.50.06

1.0

Source Zone Assumption

Note:

2.20.05

Affected Soil Zone

T-111.175 2.0

5.0

0.50 0.10

T-190.016

1.0


54

BIOSCREEN Modeling Summary, Keesler Air Force Base, SWMU 66, Mississippi:

• BIOSCREEN was used to try to reproduce the movement of the plume from 1989 (the bestguess for when the release occurred) to 1995.

• The soluble mass in soil and NAPL was estimated by integrating BTEX soil concentrationscontours mapped as part of the site soil delineation program. An estimated 2000 Kg of BTEXwas estimated to be present at the site based on GC/MS analysis of soil samples collectedfrom both the vadose and saturated zone. This value represented a source half-life of 60years with the instantaneous reaction model (the first value shown in the source half- l i febox in Figure 2), a relatively long half-life, so the 2000 Kg measured in 1995 was assumed tobe representative of 1989 conditions.

• The instantaneous reaction model was used as the primary model to try to reproduce theplume length (~ 280 ft).

• Because a decaying source was used, the source concentration on the input screen (representingconcentrations 6 yrs ago) were adjusted so the source concentration on the centerline outputscreen (representing concentrations now) were equal to 12 mg/L. Because the source decayterm is different for the first order decay and instantaneous reaction models, this simulationfocused on matching the instantaneous reaction model. The final result was a sourceconcentration of 13.68 mg/L in the center of the source zone (note on the centerline output thesource concentration is 12.021 mg/L).

• The initial run of the instantaneous reaction model indicated that the plume was too long.This indicates that there is more mixing of hydrocarbon and electron acceptors at the sitethan is predicted by the model. Therefore the longitudinal dispersivity was adjustedupwards (more mixing) until BIOSCREEN matched the observed plume length. The finallongitudinal dispersivity was 32.5 ft.

• As a check the first-order decay model was used with the BIOSCREEN default value of 2yrs. This run greatly overestimated the plume length, so the amount of biodegradation wasincreased by decreasing the solute half-life. A good match of the plume was reached with asolute half-life of 0.15 years. This is within observed ranges reported in the literature (seesolute half-life section, page 22).

• As shown in Figure 3, BIOSCREEN matches the observed plume fairly well. Theinstantaneous model is more accurate near the source while the first order decay model ismore accurate near the middle of the plume. Both models reproduce the actual plumelength relatively well.

• As shown in Figure 4, the current plume is estimated to contain 7.8 kg of BTEX. BIOSCREENindicates that the plume under a no-degradation scenario would contain 126.3 kg BTEX. Inother words BIOSCREEN indicates that 94% of the BTEX mass that has left the source since1989 has biodegraded.

• Most of the source mass postulated to be in place in 1989 is still there in 1996 (2000 kg vs. 1837kg, or 92% left).

• The current plume contains 1.0 ac-ft of contaminated water, with 1.019 acre-ft/yr of waterbeing contaminated as it flows through the source. Because the plume is almost at steadystate, 1.019 ac-ft of water become contaminated per year with the same amount beingremediated every year due to in-situ biodegradation and other attenuation processes. Thisindicates that a long-term monitoring approach would probably be more appropriate forthis site than active remediation, as the plume is no longer growing in size.

55

Figure 2. BIOSCREEN Input Screen. Keesler Air Force Base, Mississippi.

56

Figure 3. Centerline Output. Keesler Air Force Base, Mississippi.

57

Figure 4. Array Concentration Output. Keesler Air Force Base, Mississippi.


58

EXAMPLE 2

Hill Air Force Base, UST Site 870, Utah

DATA TYPE Parameter Value Source

Hydrogeology • Hydraulic Conductivity:

• Hydraulic Gradient:

• Porosity:

8.05 x 10-3 (cm/sec)

0.048 (ft/ft)

0.25

• Slug-tests results

• Static water levelmeasurements

• Estimated

Dispersion Original

• Longitudinal Dispersivity:

• Transverse Dispersivity:

• Vertical Dispersivity:

28.5 (ft)

2.85 (ft)

0 (ft)

• Based on estimated plumelength of 1450 ft and Xu’sdispersivity formula

• Note: No calibration wasnecessary to match theobserved plume length.


• Soil Bulk Density ρb:

• foc:

• Koc:

1.3

1.7 (kg/L)

0.08%

B: 38 T: 135

E: 95 X: 240


• Estimated

• Lab analysis

• Literature - use Koc = 38

Biodegradation Electron Acceptor:

Background Conc. (mg/L):

Minimum Conc. (mg/L):

Change in Conc. (mg/L):

Electron Acceptor:

Max. Conc. (mg/L):

Avg. Conc. (mg/L):

O2 NO3 SO4

6.0 17.0 100

- 0.22 - 0 - 0

5.78 17.0 100

Fe CH4

50.5 2.04

11.3 0.414

Note: Boxed values are BIOSCREENinput values.

• Based on July 1994groundwater samplingprogram conducted byParsons EngineeringScience, Inc.

General • Modeled Area Length:

• Modeled Area Width:

• Simulation Time:

1450 (ft)

320 (ft)

5 (yrs)



Source Data • Source Thickness:

• Source Concentration:

10 (ft)

(See Figure 5)


Actual Data Distance from Source (ft):

BTEX Conc. (mg/L):

340 1080 1350 1420

8.0 1.0 0.02 0.005

• Based on observedconcentration contour atsite (see Figure 5)


Array Concentration: See Figure 8


59

MW-7 <0.001

EPA-82-D 1.684

MW-12 0.035

MW-10 1.735

MW-11 <0.001

EPA-82-B <0.001

EPA-82-C 0.087

EPA-82-F <0.001 EPA-82-A

<0.001EPA-82-E <0.001

EPA-82-N <0.001

EPA-82-K <0.001

EPA-82-O <0.001

EPA-82-M 0.020

EPA-82-H <0.001

EPA-82-L 1.666

EPA-82-P 0.039

MW-8 0.373

MW-2 0.957

MW-6 0.209

MW-4 8.33

MW-1 1.906 MW-14

9.756MW-3 9.466

MW-5 3.42

1.0

8.0

ND

ND

LEGEND

Monitoring well location

July 1994 Geoprobe sampling location

BTEX concentration Isopleth, mg/L, July 19948.0

BIOSCREEN SOURCE ZONE ASSUMPTIONS

UST Site 870, Hill AFB, Utah

SCALE (ft.)

0 200 400

Affected Soil Zone

Affected Groundwater

Zone

Zone Width (ft)Source

Conc. (mg/L)

32

10025

9.02.8

1 50 0.07

FIGURE 5

32

1

Gro

undw

ater

Flo

w Dire

ctio

n

Note: Source conc. based on geometric mean between concentration isopleth contours.

0

Affected Soil Zone

Source of Data: Wiedemeier et al., 1995b.



60

BIOSCREEN Modeling Summary Hill Air Force Base, UST Site 870, Utah:

• BIOSCREEN was used to try to reproduce the movement of the plume.

• An infinite source was assumed to simplify the modeling scenario because no estimates of thesource mass were available from soil sampling data. The source was assumed to be in thehigh concentration zone of the plume area (see Figure 5). Note that the zone of affected soilwas quite large; however much of the affected soil zone downgradient of the source wasrelatively low concentration.

Two modeling approaches could be applied: 1) assuming the source zone is just downgradientof the affected soil area (near well EPA-82-C) and ignoring the area upgradient of the thispoint, and 2) modeling most of the plume with source near MW-1. Alternative 1 istheoretically more accurate, as BIOSCREEN cannot account for the contributions from anyaffected soil zone downgradient of the source. At the case of Hill AFB, however, it wasassumed that the contributions from this downgradient affected soil were relatively minorand that the main process of interest was the length of the plume from the high-concentration source zone. Therefore Alternative 2 was modeled, with the note that themiddle of the actual plume may actually have higher concentrations than would beexpected due to the contaminants in the downgradient affected soil zone.

• The instantaneous reaction model was used as the primary model to try to reproduce theplume length (~ 280 ft) as shown in Figure 7.

• The initial run of the instantaneous reaction model reproduced the existing plume withoutany need for calibration of dispersivity.

• As a check the first-order decay model was used with the BIOSCREEN default value of 2yrs. This run greatly overestimated the plume length, so the amount of biodegradation wasincreased by decreasing the solute half-life. A half-life value of 0.1 years was required tomatch the plume length, although the match in the middle in the plume was much poorer.


• As shown in Figure 8, the model was unable to calculate the mass balances. A quickevaluation shows the reason: with a seepage velocity of 1609 ft/yr and a 5 year simulationtime, the undegraded plume should be over 8000 ft long. Because the mass balance is basedon a comparison of a complete undegraded plume vs. a degraded plume, a model area lengthof 8000 ft would be required for BIOSCREEN to complete the mass balance calculation.Therefore two runs would be needed to complete the simulation: 1) a run with a modeledlength of 1450 feet to calibrate and evaluate the match to existing data, and 2) a run with amodeled length of 8000 ft to do the mass balance. The results of the second run (change ofmodel area length from 1450 ft to 8000 ft) indicate that over 99% of the mass that has leftthe source has biodegraded by the time groundwater has traveled 1450 ft.

Because the plume is no longer moving, a long-term monitoring approach is probably moreappropriate for this site than active remediation.

61

Figure 6. BIOSCREEN Input Screen. Hill Air Force Base, Utah.

62

Figure 7. Centerline Output. Hill Air Force Base, Utah.

63

Figure 8. Array Concentration Output. Hill Air Force Base, Utah.

B I O S C R E E NNatural Attenuation

Decision Support System

Version 1.4July 1997

VERSION 1.4 REVISIONS

Surface



by

Charles J. Newell, Ph.D., P.E. and R. Kevin McLeod

Groundwater Services, Inc.

Houston, Texas

James R. Gonzales

Technology Transfer Division

Air Force Center for Environmental Excellence

Brooks AFB, San Antonio Texas

BIOSCREEN 1.4 Revisions July 1997

1

INTRODUCTION

BIOSCREEN is an easy-to-use screening model which simulates remediation through naturalattenuation (RNA) of dissolved hydrocarbons at petroleum fuel release sites. The software,programmed in the Microsoft Excel spreadsheet environment and based on the Domenicoanalytical solute transport model, has the ability to simulate advection, dispersion,adsorption, and aerobic decay as well as anaerobic reactions, which have been shown to be thedominant biodegradation processes at many petroleum release sites. BIOSCREEN includesthree different model types:

1) Solute transport without decay,

2) Solute transport with biodegradation modeled as a first-order decay process (simple,lumped-parameter approach),

3) Solute transport with biodegradation modeled as an "instantaneous" biodegradationreaction (approach used by BIOPLUME models).

The model is designed to simulate biodegradation by both aerobic and anaerobic reactions. I twas developed for the Air Force Center for Environmental Excellence (AFCEE) TechnologyTransfer Division at Brooks Air Force Base by Groundwater Services, Inc., Houston, Texas.

Version 1.3 of BIOSCREEN was released in October 1996. Version 1.4 of BIOSCREEN includesa new mass flux calculation feature, a modification to the vertical dispersion term in theDomenico model, a revised description of the Domenico analytical model equation, and a minorchange to the input display. This document describes these updates and provides newbiodegradation modeling information for BIOSCREEN users. Continue to refer to the existingBIOSCREEN version 1.3 User’s Manual as the primary source of information aboutBIOSCREEN.

NEW MASS FLUX CALCULATION FEATURE IN VERSION 1.4

Version 1.4 of BIOSCREEN includes a new feature to assist users in estimating the mass flux ofcontaminants entering surface water bodies via groundwater plume discharge. This feature,included on the “Run Array” Output, provides an estimate of the mass flux of contaminants inunits of mg/day computed at specific distances away from the source (see Figure 1).

Example Application

Set up BIOSCREEN to simulate the Keesler AFB SWMU 66 plume (Example 1 in the Version1.3 User’s Manual, page 52). Assume that the plume at Keesler AFB discharges into ahypothetical stream located 210 ft away from the source zone as shown in Figure 1 (note that nosuch stream actually exists at this location). Using BIOSCREEN 1.4 with the InstantaneousReaction model, calculate the mass flux of contaminants discharging into the stream (seeExample 1 in Appendix A).

As shown in the attached Figure 4 (see Example 1 in Appendix A), the computed mass flux ofBTEX constituents within the groundwater plume at 224 ft away from the source is 1500 mg/day.Therefore, in order to achieve a target concentration in the stream of < 0.001 mg/L total BTEX, aminimum naturally-occurring flowrate of 1.5 x 106 L/day (0.61 cubic feet per second) is required.

BIOSCREEN 1.4 Revisions Ju ly 199 7

2

Obtaining Streamflow Data

Two types of stream flowrates can be used for estimating exposure concentrations, depending onthe nature of the contaminant. For contaminants with acute effects on human or aquaticreceptors (such as ammonia), a minimum flowrate such as the 2-year 7-day average low flowvalue may be appropriate. For contaminants with chronic effects on human or aquatic receptors(such as the BTEX compounds), a harmonic mean or other form of average flow could be used.

The harmonic mean is defined as:

Qn

hm

i

i n=

=

=

∑ 1

Qi1

where Qi = daily average discharge data n = number of days with data

Calculation of 10-year 7-day average low flow values is discussed in several hydrology texts,including the Handbook of Hydrology, David R. Maidment, ed. McGraw-Hill, 1993. Dailyaverage discharge data are often available through state or local agencies which regulatewastewater treatment discharges. Streamflow data are also available through the U.S.Geological Survey (USGS) for many larger streams (see the USGS World-Wide Web page:http://water.usgs.gov/swr/).

For smaller, ungaged streams, or for locations not near a gaging station, data from analternative location having similar watershed characteristics (i.e., landuse, land cover,topography, channel type, drainage area, etc.) may be used. For two locations that differ insize of the drainage area, but are otherwise similar, streamflow data from the gaged locationmay be adjusted by the ratio of drainage areas to provide an estimate of the flow at theungaged location.

Description of Calculation

The contaminant mass flux is determined using a simple calculation technique. Theconcentration in each cell of the array is multiplied by: 1) the Darcy velocity, 2) the widthassociated with each cell in the array, and 3) the thickness of the source zone. The plume massflux for a particular cross section is then determined by summing the five values in the array forthat cross section. The calculation technique is disabled when vertical dispersion is used, asthe vertical concentration profile is no longer uniform. In addition, the mass flux calculationshould only be used for gaining streams (streams where groundwater discharges into surfacewater) and should not used for losing streams (streams that recharge groundwater).

The calculation approach is approximate, and other averaging techniques (use of geometricmeans, etc.) might provide different results. Because the model defines the plume cross sectionwith only 5 points, the computed plume mass flux may appear to be slightly higher for adowngradient point than an upgradient point in some instances. As illustrated in the example,the mass flux estimates are sensitive to the model width, and for best results users should adjustthe model width so that the contaminant plume covers most of the calculated array (comparemass flux results from a simulation using a 200 ft model width, Figure 4, to mass flux results froma simulation using a 50 ft model width, Figure 6). Users should assume that the mass fluxestimates are probably accurate to ± 50%.


3

NEW KILOGRAM TO GALLONS CONVERSION FEATURE IN VERSION 1.4

Version 1.4 of BIOSCREEN also includes a new feature to show users how much volume themass of contaminants displayed in the Array Output screen represents. For example, i fBIOSCREEN estimates that the Actual Plume Mass is 7.8 Kg (see Figure 4) , the model willconvert this into an effective contaminant volume of 2.4 gallons of organic, using a density valueof 0.87 g/mL (representative of the density of a BTEX mixture). The following mass values willbe converted to volumes: i) Plume Mass if No Biodegradation, ii) Actual Plume Mass, iii) PlumeMass Removed by Biodegradation, iv) Original Mass in Source (Time = 0 Years), and v) Mass inSource Now (Time = X Years).

To display the data converted into gallons, the user should click the “See Gallons” button in the“Plume and Source Masses” region of the Array Output screen. A dialog box appears withseveral common fuel constituents (average BTEX, benzene, toluene, ethylbenzene, and para-xylene) and their densities in g/mL. If an alternative value for constituent densities isavailable, this number can be entered into the “Density” box. When the “OK” button is pressed,the dialog box disappears and the plume and source mass calculations in Kg are replaced withvolume information in gallons. To convert back to mass values, click on the “See Kg” button.

RELATED REFERENCES FOR BIOSCREEN MODELING

Ollila (1996) provides a good comparison of the Domenico model with the instantaneousreaction superposition method against BIOPLUME II. Rifai et al. (1997) summarize the theoryand use of AFCEE’s BIOPLUME III model. Nevin et al. (1997) describe software for derivingfirst-order decay coefficients for steady-state plumes from actual site data.

Nevin, J. P., J.A. Connor, C.J. Newell, J.B. Gustafson, K.A. Lyons, 1997. “FATE 5: A Natural AttenuationCalibration Tool for Groundwater Fate and Transport Modeling,”, Petroleum Hydrocarbons andOrganic Chemicals in Groundwater Conference, NGWA, Houston, Texas, Nov. 1997.

Ollila, P.W., 1996. Evaluating Natural Attenuation With Spreadsheet Analytical Fate and TransportModels. Ground Water Monitoring and Remediation, Vol. XVI, No. 24, pp. 69-75.

Rifai, H.S., C.J. Newell, J.R. Gonzales, S. Dendrou, L. Kennedy, and J. Wilson, 1997. BIOPLUME III NaturalAttenuation Decision Support System Version 1.0 User’s Manual. Air Force Center for EnvironmentalExcellence, Brooks AFB, Texas (in press).

IMPACT OF NON-BTEX CONSTITUENTS ONBIOSCREEN MODELING

BTEX constituents only comprise a small percentage of the total organic mass in gasoline and JP-4 mixtures. However, the best available information suggests that most JP-4 and gasolineplumes will be dominated by BTEX components, and that only a small fraction of the plumescontain dissolved non-BTEX compounds. This is due to the BTEX compounds having very highsolubilities relative to the remaining fraction of organic mass in these fuel mixtures. In otherwords, most of the non-BTEX constituents of gasoline and JP-4 are relatively insoluble, creatingdissolved-phase plumes that are dominated by the BTEX compounds. The followingcalculations support this conceptual model of BTEX-dominated plumes from JP-4 and gasoline.For additional supporting data and calculations, see Section 3.3.2 of Weidemeier et al., 1995.

Gasoline composition data presented by Johnson et al. (1990a and 1990b), and JP-4 compositiondata presented by Stelljes and Watkin (Stelljes and Watkin, 1993; data adapted from OakRidge National Laboratory, 1989) were used to determine the effective solubility of thesehydrocarbon mixtures in equilibrium with water (effective solubility = mole fraction x purephase solubility; see Bedient, Rifai, and Newell 1994). The total effective solubility of all the


4

constituents was then compared to the effective solubility of the BTEX constituents. Thefollowing tables show this calculation for fresh gasoline, two weathered gasolines, and JP-4.

FRESH GASOLINE(data from Johnson et al., 1990)

Constituent MassFraction

MoleFraction

Pure-Phase Solubility(mg/L)

Effective Solubility(mg/L)

Benzene 0.0076 0.0093 1780 17Toluene 0.055 0.0568 515 29Ethylbenzene 0.0 0.0 152 0Xylenes 0.0957 0.0858 198 17

TOTAL BTEX 0.16 0.15 152 - 1780 (range) 63

58 Compounds 0.84 0.85 0.004 - 1230 (range) 30

TOTAL 1.00 1.00 - 93

% BTEX = (63 mg/L) ÷ (93 mg/L) = 68 %

WEATHERED GASOLINE # 1(data from Johnson et al., 1990a)


MoleFraction


Effective Solubility

(mg/L)Benzene 0.01 0.0137 1780 24Toluene 0.1048 0.1216 515 63Ethylbenzene 0.0 0.0 152 0Xylenes 0.1239 0.1247 198 25

TOTAL BTEX 0.24 0.26 152 - 1780 (range) 112

58 Compounds 0.76 0.74 0.004 - 1230 (range) 14

TOTAL 1.00 1.00 - 126

% BTEX = (112 mg/L) ÷ (126 mg/L) = 89 %

WEATHERED GASOLINE #2(data from Johnson et al., 1990b)


MoleFraction


Effective Solubility(mg/L)

Benzene 0.0021 0.003 1780 5Toluene 0.0359 0.043 515 22Ethylbenzene 0.013 0.014 152 2Xylenes 0.080 0.084 198 15

TOTAL BTEX 0.13 0.14 152 - 1780 (range) 44

64 Compounds 0.87 0.86 0.004 - 1230 (range) 21

TOTAL 1.00 1.00 - 65

% BTEX = (44 mg/L) ÷ (65 mg/L) = 68 %


5

VIRGIN JP-4(data from Stelljes and Watkin, 1993; Oak Ridge N. Lab, 1989)


MoleFraction

Pure-Phase Solubility

(mg/L)

Effective Solubility

(mg/L)Benzene 0.005 0.023 1780 42Toluene 0.0133 0.053 515 27Ethylbenzene 0.0037 0.013 152 2Xylenes 0.0232 0.080 198 16

TOTAL BTEX 0.045

(4.5%)0.168 152 - 1780 (range) 87

13 Compounds 0.27

(27%)

0.832 0.004 - 1230 (range) 4

TOTAL 0.315

(31.5)%1.000 - 91

% BTEX = (87 mg/L) ÷ (91 mg/L) = 95 %

In each of these four fuel samples, BTEX compounds comprise the majority of the dissolvedorganic mass in equilibrium with water. The non-BTEX components represent a much smallerportion of the dissolved mass. As expected, the theoretical dissolved-phase concentrationsfrom these samples are much higher than what is typically observed in groundwater samplesdue to factors such as dilution, the heterogeneous distribution of non-aqueous phase liquids, andthe low level of mixing occurring in aquifers (see Bedient, Rifai, and Newell, 1994 for a morecomplete discussion).

Note that the total effective solubility of weathered gasoline #1 (126 mg/L) is greater thanthe total effective solubility of the fresh gasoline (93 mg/L). A comparison of the two samplesindicates that the fresh gasoline includes a significant mass of light, volatile compounds tha thave pure-phase solubilities that are much lower than that of the BTEX compounds (e.g.,isopentane with a vapor pressure of 0.78 atm and a solubility of 48 mg/L, compared tosolubilities of 152 -1780 mg/L for the BTEX compounds). When these light compounds areweathered (probably volatilized), the mole fractions of the BTEX components (the onlyremaining components with any significant solubility) increase, thereby increasing the totaleffective solubility of the weathered gasoline. On the other hand, weathered gasoline #2 hasa total effective solubility that is significantly lower than fresh gasoline (65 mg/L vs. 93mg/L), suggesting that this gasoline has weathered to the point where there has beensignificant removal of both volatile and soluble components from the gasoline.

In their analysis, Stelljes and Watkin (1993) identified only 17 compounds representing 31% bymass of a complete JP-4 mixture. However, a comparison of the relative make-up of thequantified mixture to the reported make-up of JP-4 (also from Stelljes and Watkin, 1993) showsthe various classes of organic compounds to be equivalently represented in both mixtures. Thequantified mixture appears to be generally representative of the complete JP-4 mixture.

% benzenes, alkylbenzenes in identified compounds: 14% (note: equals 4.5% of 31.5%)% benzenes, alkylbenzenes in complete JP-4 mixture: 18% (from Stelljes and Watkin, 1993)


6

% branched alkanes in all identified compounds: 26%% branched alkanes in complete JP-4 mixture: 31%

% cycloalkanes in all compounds identified: 7%% cycloalkanes in complete JP-4 mixture: 16%

% naphthalenes in all compounds identified: 6%% naphthalenes in complete JP-4 mixture: 3%

% normal alkanes in all compounds identified: 47%% normal alkanes in complete JP-4 mixture: 32%

Finally, it is important to note that there is considerable variability among different freshfuels, and even more variation among weathered fuels. Therefore, these results should only beused as a general indicator that the BTEX compounds comprise the majority of the solublecomponents in plumes originating from JP-4 and gasoline releases. These results should not beused as absolute, universal values for all sites.

With regard to biodegradation modeling, however, it is probably appropriate to assume thatBTEX compounds exert the majority (i.e. ~ 70% or greater) of the electron acceptor demand a tJP-4 and gasoline sites. To make modeling BTEX using the instantaneous reaction approachmore accurate, however, the total concentrations of available electron acceptors can be reducedby some fraction to account for the electron acceptor demand posed by biodegradable non-BTEXorganics in groundwater. Two examples of how to account for the impact for non-BTEXcomponents is to multiply all electron acceptor/by-product concentrations used in the model byeither i) the ratio of BTEX/TOC concentrations, or ii) the ratio of BTEX/BOD concentrations ( i fTOC and BOD data are available). If these data are not available, a conservative approachwould be to reduce all available electron acceptor/by-product concentrations used in the modelby 30% to account for the possible impacts of non-BTEX organics in groundwater.

References for BTEX-Dominated Plumes

Bedient, P. B., H.S. Rifai, and C.J. Newell, Groundwater Contamination: Transport and Remediation, Prentice-Hall, 1994.

Johnson, P.C., M.W. Kemblowski, and J.D. Colthart. 1990a. Quantitative Analysis of Cleanup ofHydrocarbon-Contaminated Soils by In-Situ Soil Venting. Ground Water, Vol. 28, No. 3. May - June,1990, pp 413-429.

Johnson, P.C., C.C. Stanley, M.W. Kemblowski, D.L. Byers, and J.D. Colthart. 1990b. A Practical Approach tothe Design, Operation, and Monitoring of In Site Soil-Venting Systems, Ground Water Monitoring andRemediation, Spring, 1990, pp 159-178.

Oak Ridge National Laboratory, 1989. The Installation Restoration Program Toxicology Guide, DOEInteragency Agreement No. 1891-A076-A1, Volumes III and IV, July, 1989.

Stelljes, M.E., and G.E. Watkin, 1993. "Comparison of Environmental Impacts Posed by DifferentHydrocarbon Mixtures: A Need for Site Specific Composition Analysis,", in Hydrocarbon ContaminatedSoils and Groundwater, Vol. 3, P.T. Kostecki and E.J. Calabrese, Eds., Lewis Publishers, Boca Raton.

Wiedemeier, T. H., Wilson, J. T., Kampbell, D. H, Miller, R. N., and Hansen, J.E., 1995. "Technical Protocol forImplementing Intrinsic Remediation With Long-Term Monitoring for Natural Attenuation of FuelContamination Dissolved in Groundwater (Revision 0)", Air Force Center for Environmental Excellence,Brooks AFB, Texas, Nov., 1995.


7

CHANGES FROM BIOSCREEN 1.3

Display of Source Half-Life Values

The input screen for Version 1.4 has been modified to emphasize that BIOSCREEN generatestwo different source half-lives when a value for “Soluble Mass in Source NAPL, Soil” isentered. As discussed on page 31 of the Version 1.3 User’s Manual, two half-lives are reported,one for the Instantaneous Reaction model and one for the No Degradation or First Order Decaymodels. Version 1.3 of BIOSCREEN presented both half-lives in one black box (black inputboxes designate intermediate values calculated by the model). As part of the Version 1.4modifications, the single box for source half-lives has been replaced with two boxes, oneshowing the source half-life calculated using the instantaneous reaction model and one showingthe source half-life calculated using the No Degradation or First Order Decay models. Thechange was made to emphasize that two different values are calculated by BIOSCREENdepending on which biodegradation model is employed (see page 31 of the Version 1.3 User’sManual).

Vertical Dispersion Term

As explained in the Version 1.3 User’s Manual, BIOSCREEN has been configured so that thedefault vertical dispersivity is set to zero (see Appendix A.4 in the Version 1.3 User’s Manual).In BIOSCREEN 1.3, however, if the user opts to use a non-zero vertical dispersivity estimate,the software may overestimate the effects of vertical dispersion in some cases, as describedbelow.

BIOSCREEN 1.3 was coded so that vertical dispersion is assumed to occur in both directions asthe contaminants travel away from the source zone (i.e., downwards and upwards). For sourcezones located in the middle of a thick aquifer, or in cases where recharge produces a clean zoneon top of the plume, this would be an appropriate approach. For source zones located at the topof an aquifer (the case at most petroleum release sites), upward vertical dispersion above thewater table does not occur (unless recharge is significant), and therefore the model couldoverestimate the effects of dispersion. While the vertical dispersion term in the Domenicoanalytical model expression in the Version 1.3 User’s Manual was correct, showing verticaldispersion in only one direction (see Appendix A.1), the Version 1.3 model actually simulatesvertical dispersion in both directions.

In BIOSCREEN 1.4, the default approach of no vertical dispersion is still recommended. Thesoftware code has been changed, however, so that there is vertical dispersion is modeled in thedownward direction only. (If a user would like to use BIOSCREEN 1.4 with dispersion in bothdirections, multiply the vertical dispersivity estimate by a factor of 4 and enter the result asthe vertical dispersivity. This will have the effect of simulating vertical dispersion occurringin two directions).

Most users will not notice any effect with this change, as BIOSCREEN’s default verticaldispersivity is set near zero corresponding to no vertical dispersion. BIOSCREEN 1.3 onlyoverestimates the effects of vertical dispersion if: 1) the default dispersivity value of zero isreplaced with a non-zero vertical value and 2) the source zone is located at the top of an aquiferthat does not have significant recharge.


8

Appendix A.1 Domenico Analytical Model Equation

The Domenico analytical model expression provided in Appendix A.1 of the BIOSCREENVersion 1.3 User’s Manual incorrectly showed how the superposition term was employed, wasunclear about the separation of the first order decay model and the instantaneous reactionmodel, and did not include the source decay term. Revised equation descriptions are providedbelow and replace the single equation shown on page 41 of the Version 1.3 User’s Manual. Notethat the equations encoded in the software were not in error and have not been modified (exceptas described above with regard to vertical dispersion).

Domenico Model with First Order Decay Algorithm

Csource

Dispersivity

αz

αy

αx

Y

Z

x

αy

C (x, y, 0 )

WaterTableSource

C x y o t C k t x v

xv

erfcx vt v

vt

erfy Y

x

o s

xx

x

x

y

, , , exp ( / )

exp /

/

( )

/

/

/

/

/

( ) = − −[ ]

− +( )( )

− +( )( )

+( )( )

1

8 21 1 4

1 4

2

2

2

1 2

1 2

1 2

1 2

αλα

λα

α

α

−−( )

( )

( )( )

−−( )

( )

erfy Y

x

erfZ

xerf

Z

x

y

z z

//

/ /

2

2

2 2

1 2

1 2 1 2

α

α α

where: vK i

Re

= ⋅θ

Domenico Model with Instantaneous Reaction Superposition AlgorithmCsource

Dispersivity

αz

αy

αx

Y

Z

x

αy

C (x, y, 0 )

WaterTableSource

C x y o t C k t x v BC

erfcx vt

vt

erfy Y

xerf

y Y

x

o s

x

y y

, , , exp ( / )

( )

/ /

/

/ /

( ) = − −[ ] +( )−( )

+( )( )

−−( )

( )

1

8 2

2

2

2

2

1 2

1 2 1 2

α

α α

( )( )

−−( )

( )

− erf

Z

xerf

Z

xBC

z z2 21 2 1 2α α/ /

where: vK i

Re

= ⋅θ

BC

C ea

UFn

n

= Σ ( )

continued


9

continued

Definitions

BC Biodegradation capacity (mg/L)

C(x,y,z,t) Concentration at distance x downstream of

source and distance y off centerline of plume at

time t (mg/L)

Cs Concentration in Source Zone (mg/L)

Co Concentration in Source Zone at t=0 (mg/L)

x Distance downgradient of source (ft)

y Distance from centerline of source (ft)

z Vertical Distance from groundwater surface to

measurement point (assumed to be 0;

concentration is always assumed to be at top

of water table).

C(ea)n Concentration of electron acceptor (or by-

product equivalent) n in groundwater (mg/L)

UFn Utilization factor for electron acceptor n (i.e., mass ratio

of electron acceptor/by-product to hydrocarbon consumed

in biodegradation reaction)

αx Longitudinal groundwater dispersivity (ft)

αy Transverse groundwater dispersivity (ft)

αz Vertical groundwater dispersivity (ft)

λ First-order decay coefficient for dissolved contaminants (yr-1)

θe Effective soil porosity

υ Contaminant velocity in groundwater (ft/yr)

K Hydraulic conductivity (ft/yr)

R Constituent retardation factor

i Hydraulic gradient (ft/ft)

Y Source width (ft)

Z Source depth (ft)

t Time (yr)

ks First-order decay term for source concentration (yr-1)

ACKNOWLEDGMENTS

BIOSCREEN was developed for the Air Force Center for Environmental Excellence, BrooksAFB, San Antonio, Texas by Groundwater Services, Inc.

AFCEE Technology TransferDivision Chief:

Mr. Marty Faile

AFCEE Project Officer: Mr. Jim Gonzales

BIOSCREEN Developers: Charles J. Newell, Ph.D., P.E. and R. Kevin McLeod

Groundwater Services, Inc. phone: 713 522-63002211 Norfolk Suite 1000 fax: 713 522-8010Houston, Texas 77005 cjnewell@gsi-net. com

rkmcleod@gsi-net. com

BIOSCREEN Manual: Charles J. Newell, Ph.D., P.E.Groundwater Services, Inc.

Contributors to BIOSCREENVersion 1.4:

R. Todd Fisher

The Air Force Center for Environmental Excellence is distributing BIOSCREEN 1.4 via:

EPA Center for Subsurface ModelingSupport (CSMoS)NRMRL/SPRDP.O. Box 1198Ada, Oklahoma 74821-1198

• Phone: (405) 436-8594

• Fax: (405) 436-8718

• Bulletin Board: (405) 436-8506(14,400 baud- 8 bits -1 stop bit -no parity).

• Internet: http://www.epa.gov/ada/kerrlab.html(Electronic manuals will be in .pdf format; mustdownload Adobe Acrobat Reader to read and printpdf files.)

Note that first-time users should download:

1) The BIOSCREEN 1.4 software,2) The BIOSCREEN 1.3 User’s Manual, and3) The BIOSCREEN 1.4 Revisions document.


A-1

APPENDIX 1. BIOSCREEN Version 1.4 EXAMPLE

Example 1: SWMU 66, Keesler AFB, Mississippi

• Input Data






• Fig. 5 BIOSCREEN Input Data, 50 ft Model Width

• Fig. 4 BIOSCREEN Array Output, 50 ft Model Width


A-2

BIOSCREEN EXAMPLE 1

Keesler Air Force Base, SWMU 66, Mississippi

DATA TYPE Parameter Value Source of Data

Hydrogeology • Hydraulic Conductivity:• Hydraulic Gradient:• Porosity:

1.1 x 10-2 (cm/sec)0.003 (ft/ft)0.3

• Slug-tests results• Static water level

measurements• Estimated

Dispersion Original:


After Calibration:


13.3 (ft)1.3 (ft)0 (ft)

32.5 (ft)3.25 (ft)0 (ft)

• Based on estimated plumelength of 280 ft andXu/Eckstein relationship

• Based on calibration toplume length (Note this iswell within the observedrange for long. dispersivity;see Fig. A.1 in AppendixA..3. Remember to convertfrom feet to meters beforeusing the chart).


• Soil Bulk Density ρb:• foc:• Koc:

1.0

1.7 (kg/L)0.0057%B: 38 T: 135E: 95 X: 240


• Estimated• Lab analysis• Literature - use Koc = 38

Biodegradation Electron Acceptor:Background Conc. (mg/L):Minimum Conc. (mg/L):Change in Conc. (mg/L):

Electron Acceptor:Max. Conc. (mg/L):Avg. Conc. (mg/L):

O2 NO3 SO4 2.05 0.7 26.2- 0.4 - 0 - 3.8 1.65 0.7 22.4

Fe CH4 36.1 7.4 16.6 6.6

Note: Boxed values areBIOSCREEN input values.

• Based on March 1995groundwater samplingprogram conducted byGroundwater Services, Inc.

General • Modeled Area Length:• Modeled Area Width:• Simulation Time:

320 (ft)200 (ft), 50 (ft)6 (yrs)



Source Data • Source Thickness:• Source Concentration:

10 (ft)(See Figure 1)


Actual Data Distance From Source (ft):BTEX Conc. (mg/L):

30 60 180 280 5.0 1.0 0.5 0.001

• Based on observedconcentrations at site


Array Concentration: See Figure 4, 6


A-3

SWMU 66 Site, Keesler AFB, Mississippi

LEGEND

FIGURE 1

MW9-50.001

T-210.210

MW9-4ND

MW9-6ND

MW9-2ND

0

MW9-10.003

T-160.596

10

T-7ND

T-5ND

T-3ND

T-1ND

T-80.793

Monitoring well locationTemporary cone penetrometer (CPT) piezometer locationTotal BTEX detected in groundwater sample, mg/L0.003

No BTEX detectedND

Zone

321

Width (ft)Actual Source Conc.

in 1995 (mg/L)

143020

12

BTEX concentration isopleth, mg/L, March 1995

SCALE (ft.)

0 40 80

BIOSCREEN SOURCE ZONEASSUMPTIONS

AffectedSoil Zone

AffectedGroundwater

Zone

1

2

3

Groundwater Flow Direction

T-1314.1

Source conc. based on Geometric mean betweenconcentration isopleth contours.

Adjusted Model SourceConc. in 1989 (mg/L)

13.72.50.06

1.0


Note:

2.20.05

Affected Soil Zone

T-111.175 2.0

5.0

0.50 0.10

T-190.016

1.0

210 ft

Hypothetical Stream210 ft from Source


A-4

BIOSCREEN Modeling Summary, Keesler Air Force Base, SWMU 66, Mississippi:

• BIOSCREEN was used to try to reproduce the movement of the plume from 1989 (the bestguess for when the release occurred) to 1995.

• The soluble mass in soil and NAPL was estimated by integrating BTEX soil concentrationscontours mapped as part of the site soil delineation program. An estimated 2000 Kg of BTEXwas estimated to be present at the site based on GC/MS analysis of soil samples collectedfrom both the vadose and saturated zone. This value represented a source half-life of 60years with the instantaneous reaction model (the first value shown in the source half- l i febox in Figure 2), a relatively long half-life, so the 2000 Kg measured in 1995 was assumed tobe representative of 1989 conditions.

• The instantaneous reaction model was used as the primary model to try to reproduce theplume length (~ 280 ft).

• Because a decaying source was used, the source concentration on the input screen (representingconcentrations 6 yrs ago) were adjusted so the source concentration on the centerline outputscreen (representing concentrations now) were equal to 12 mg/L. Because the source decayterm is different for the first order decay and instantaneous reaction models, this simulationfocused on matching the instantaneous reaction model. The final result was a sourceconcentration of 13.68 mg/L in the center of the source zone (note on the centerline output thesource concentration is 12.021 mg/L).

• The initial run of the instantaneous reaction model indicated that the plume was too long.This indicates that there is more mixing of hydrocarbon and electron acceptors at the sitethan is predicted by the model. Therefore the longitudinal dispersivity was adjustedupwards (more mixing) until BIOSCREEN matched the observed plume length. The finallongitudinal dispersivity was 32.5 ft.

• As a check the first-order decay model was used with the BIOSCREEN default value of 2yrs. This run greatly overestimated the plume length, so the amount of biodegradation wasincreased by decreasing the solute half-life. A good match of the plume was reached with asolute half-life of 0.15 years. This is within observed ranges reported in the literature (seesolute half-life section, page 22).


• As shown in Figure 4, the current plume is estimated to contain 7.8 kg of BTEX. BIOSCREENindicates that the plume under a no-degradation scenario would contain 126.3 kg BTEX. Inother words BIOSCREEN indicates that 94% of the BTEX mass that has left the source since1989 has biodegraded.

• Most of the source mass postulated to be in place in 1989 is still there in 1996 (2000 kg vs. 1837kg, or 92% left).

• The current plume contains 1.0 ac-ft of contaminated water, with 1.019 acre-ft/yr of waterbeing contaminated as it flows through the source. Because the plume is almost at steadystate, 1.019 ac-ft of water become contaminated per year with the same amount beingremediated every year due to in-situ biodegradation and other attenuation processes. Thisindicates that a long-term monitoring approach would probably be more appropriate forthis site than active remediation, as the plume is no longer growing in size.


A-5

• A hypothetical stream is assumed to be located approximately 210 ft downgradient of thesource (note no such stream exists at the actual site). Using an estimated model width of 200ft (see Figure 2), a mass flux of 1500 mg/day is calculated (see Figure 4) at a distance of 224ft away from the source (the closest point calculated by BIOSCREEN).

Users should be aware that the mass flux calculation is sensitive to the model widthassigned in Section 6 of the input screen (see Figure 2). A model width of 200 ft was used inthe original example so that most of the “no degradation” plume was in the array,allowing calculation of the plume and source masses (see pg. 34-35 of the BIOSCREEN Ver.1.3 Manual for a more detailed explanation).

For the mass flux calculation, however, a more accurate result will be obtained by selecting awidth where most of the plume of interest (in this cased the instantaneous reaction plume)appears across the array. As shown in Figures 5 and 6, a model width of 50 ft was selected sothat the instantaneous reaction plume covered most of the BIOSCREEN array. With thiswidth, a mass flux value of 860 mg/day was calculated. This is a more accurate estimate ofthe mass flux than the 1500 mg/day calculated above.


A-6

Figure 2. BIOSCREEN Input Screen. Keesler Air Force Base, Mississippi. (Note: longitudinal dispersivity has been changed from the original computedvalue of 13.3 ft. to 32.5 ft. during calibration.)


A-7

Figure 3. Centerline Output. Keesler Air Force Base, Mississippi.


A-8

Figure 4. Array Concentration Output. Keesler Air Force Base, Mississippi.


A-9

Figure 5. BIOSCREEN Input Screen. Keesler Air Force Base, Mississippi, with 50 ft. modeled area width.


A-10

Figure 6. Array Concentration Output. Keesler Air Force Base, Mississippi, with 50 ft. modeled area width.

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