PA 625/1-81-013 (COE EM1110-1-501)

PROCESS DESIGN MANUAL FOR

LAND TREATMENT OF MUNICIPAL WASTEWATER

U. S. ENVIRONMENTAL PROTECTION AGENCY

U. S. ARMY CORPS OF ENGINEERS

U. S. DEPARTMENT OF INTERIOR

U. S. DEPARTMENT OF AGRICULTURE

October 1981

Pub1 i shed by

U. S. Envi ronmental P r o t e c t i o n Agency Center f o r Environmental Research In fo rma t ion

C inc inna t i , Ohio 45268

ACKNOWLEDGMENTS

This manual presents the state-of-the-art on process design for land treatment systems., It replaces the process design manual with the same title, published in October 1977. Preparation of this manual was sponsored by th.e U.S. Environmental Protection Agency (EPA), Office of Research and Development, and Office of Water; the U.S.ArmyCclrps of Engineers; the U.S. Department of the Interior (USDI), Office of Water Research and Technology; and the U.S. Depa.rtment, of Agriculture (USDA), Office of Environmental Quality and Farmers Home Administration. An interagency,coordinating committee representing these sponsors was established; this committee then selectedateamof contract authors. Contract administration was provided by EPA CERI, Cincinnati, Ohio.

PROJECT OFFICER: Dr. JameslE. Smith Jr., EPA, CERI. Dr. Smith was also chairmanlo the interagency coordi.nating committee. Assistance in contract administration was provided by Enviro Control, Inc., under the direction of Mr. Tors ten Rothman . I

I CONTRACTOR: Metcalf & Eddy! Inc., Sacramento, California.

Supervision and Principal ~uthors: Ronald W. Crites, ~roject:~anager, E.L. Meyer and R.G. Smith1

Staff Authors: M. Walker, K. Alston, M. Alpert, C. Stein

I

Editing and Review: I

F. Burton, J. Miller, C. Iound

Consultant Authors: Dr. A. Wallace, University of Idaho; Dr. W. Nutter, University of Georgia; Mr. D. Hinrichs, Culp/Wesner/ Culp; Mr. B. Whitson, Mr. D. Deemer, Dr. 0. Aly, and Mr. L. Gilde, Campbell Soup Company; Dr. E. Myers, Williams & Works, Inc.; Mr. D. Hirschbrunner and Ms. D. Parkes, Bruce Gilmore & Associates, Inc.

ACKNOWLEDGMENTS

A technical workgroup composed of members from the spon- soring agencies, as well as other invited experts, was formed. In addition, arnultidisciplinary group of engineers and scientists also furnished technical review. Under the direction of its chairman, the workgroup defined the scope of the effort, supervised the work of the contractor, re- viewed the manual, and provided technical editing and input to the manual.

CHAIRMAN: Sherwood C. Reed, USA CRREL

WORKGROUP : EPA: Mr. R.E. Thomas, Dr. J.E. Smith Jr.,

Dr. C. Harlin, Mr. W. Whittington, Mr. R. Bastian, Dr. H. Thacker, Dr. N. Kowal, Mr. R. Dean, Mr. J. Ariail, Dr. C. Enfield, Mr. J. Roesler, Mr. W. Huang, Mr. J. Smith

U. S. Army: Mr. N. Urban, Mr. D. Lamont, Mr. W. Medding, Mr. P. Carmichael, Dr. I. Iskandar, Mr. J. Martel, Mr. J. Bouzoun, Dr. R. Lee, Mr. M. Cullinane, Mr. J. Bauer, Dr. S. Schaub, Dr. H. McKim

USDA: Mr. P. Smith, Mr. C. Rose, Mr. G. Deal, Dr. H. Bouwer, Mr. W. Opfer, Dr.D.Urie, Mr. R. Phillips, Dr. D. Clapp

USDI : Mr. .R. Madancy USDOE : Ms. 3. Broomfield NSF : Dr. E. Bryan

Academic Institutions and State Agencies: Dr. M. Kirkham, Dr. E. Lennette, Dr. W. Sopper, Dr. R. Smith, Dr. A. Overman, Dr. R. Abernathy, Dr. M. Overcash, Dr. A. Erickson, Mr. D. Kendrick

Invited Technical Reviewers: Mr. B. Seabrook, Mr. T. Jenkins, Mr. J. Kreissl, Mr. A. Palazzo, Dr. E. Smith, Ms. H. ~arquhar, Dr. R. Lewis, Dr. T. Asano, Mr. T. Rothman, Mr. R. Sletten, Mr. G, Abele

ABSTRACT t

This manual presents a rattonal procedure for the design of land treatment systems. Slow rate, rapid infiltration, and overland flow processes for the treatment of municipal wastewaters are discussed in detail, and the design concepts and criteria are presented. A two-phased planning approach to site investigation and selection is also presented.

The manual includes examples of each process design. Information on field investigations is presented along with special considerations for small scale systems. Equations and procedures are included to allow calculations of energy requirements for land treatment systems. Potential health and environmental effects and corresponding mitigation measures are discussed. 1

CONTENTS

Chapter

ACKNOWLEDGMENTS I ACKNOWLEDGMENTS I1 ABSTRACT CONTENTS FIGURES TABLES

1 INTRODUCTION AND PROCESS CAPABILITIES Purpose - . . , Scope Treatment Processes Slow Rate Process 1.4.1 Process Objectives 1.4.2 Treatment Performance Rapid Infiltration 1.5.1 Process Objectives 1.5.2 Treatment Performance Overland Flow 1.6.1 Process Objectives 1.6.2 Treatment Performance Combination Systems Guide to Intended Use of the Manual References

2 PLANNING AND TECHNICAL ASSESSMENT 2.1 Planning Procedure 2.2 Phase 1 Planning

2.2.1 Preliminary Data 2.2.2 Land Treatment System Suitability 2.2.3 Land Area Requirements 2.2.4 Site Identification 2.2.5 Site Screening

2.3 Phase 2 Planning 2.3.1 Field Investigations 2.3.2 Selection of Preliminary

Design Criteria 2.3.3 Evaluation of Alternatives 2.3.4 Plan Selection ~

2.4 Water Rights and Potential Water Rights Conflicts 2.4.1 Natural Watercourses 2.4.2 Surface Waters 2.4.3 Percolating Waters (Ground Waters) 2.4.4 Sources of Information

2.5 References

Page

ii iii iv v xv

xviii

CONTENTS (Continued)

Chapter ~ I

3 FIELD 3.1 3.2

INVESTIGATIONS Introduction Physical Properties 3.2.1 Shallow Profile Evaluation 3.2.2 Profile Evaluation to

Greater Depths Hydraulic Properties 3.3.1 Saturated Hydraulic Conductivity 3.3.2 Infiltration Capacity 3.3.3 Specific Yield 3.3.4 Unsaturated Hydraulic Conductivity 3.3.5 Profile Drainage Infiltration Rate Measurements 3.4.1 Floodang Basin Techniques 3.4.2 Cylinder Infiltrometers 3.4.3 Sprinkler Infiltrometers Measurement of Vertical Hydraulic Conductivity , 3.5.1 Double-Tube Method 3.5.2 Air Entry Permeameter Ground Water 3.6.1 ~epth/Hydrostatic Head 3.6.2 Flow 3.6.3 Ground Water Quality Soil Chemical Properties 3.7.1 Interpretation of Soil

Chemical Tests 3.7.2 Phosphorus Adsorption Test References I

I

4.1 Introduction 4.2 Process Performance

4.2.1 BOD and Suspended Solids Rem0va.L 4.2.2 Nitrogen 4.2.3 Phosphorus 4.2.4 Trace Elements 4.2.5 Microorganisms 4.2.6 Trace organics

4.3 Crop Selection 4.3.1 Guidelines for Crop Selection 4.3.2 Crop Characteristics

4.4 Preapplication Treatment 4.4.1 Preapplication Treatment for

Storage and During Storage 4.4.2 Preapplication Treatment to

Protect Distribution Systems I

Page

CONTENTS (Continued)

Chapter Page 4.4.3 Industrial Pretreatment 4-28

4.5 Loading Rates and Land Area Requirements 4-28 4.5.1 Hydraulic Loading Rate Based

on Soil Permeability 4-28 4.5.2 Hydraulic Loading Rate Based

on Nitrogen Limits 4-30 4.5.3 E[ydraulic Loading Rate Based

on Irrigation Requirements 4-34 4.5.4 Land Area Requirements 4-35

4.6 Storage Requirements 4-37 4.6.1 Estimation of Volume Requirements

Using Storage Water Balance Calculations 4-37

4.6.2 Estimated Storage Volume Requirements Using Computer Programs 4-39

4.6.3 Final Design Storage Volume Calculations ' 4-41

4.6.4 Storage Pond Design Considerations 4-43 4.7 Distribution System 4-44

4.7.1 Surface Distribution Systems 4-44 4.7.2 Sprinkler Distribution Systems 4-45 4.7.3 Service Life of.Distribution

System Components 4-53 4.8 Drainage and Runoff Con t ro l 4-53

4*.8.1 Subsurface Drainage Systems 4-53 4.8.2 Surface Drainage and Runoff Control 4-56

4.9 System Management 4-58 4.9.1 Soil Management 4-58 4.9.2 Clrop Management 4-61

4.10 System Monitoring 4-64 4.10.1 Water Quality Monitoring 4-65 4.10.2 Soils Monitoring 4-65 4.10.3 Vegetation Monitoring 4-66

4.11 Facilities Design Guidance 4-66 4.12 References 4-68

5 RAPID INFILTRATION PROCESS DESIGN 5.1 Introduction

5.1.1 RI Hydraulic Pathway 5.1.2 Site Work

5.2 Process Performance 5.2.1 BOD and Suspended Solids 5.2.2 Nitrogen 5.2.3 Phosphorus 5.2.4 Trace Elements 5.2.5 Microorganisms 5-2.6 Trace Organics

vii ,

CONTENTS (Continued)

Chapter Page 5.3 ~etermination of Preapplication

Treatment Level 5.3.1 EPA Guidance 5.3.2 Water,Quality Requirements

and Treatment Goals 5.4 ~etermination of Hydraulic

Loading Rate 5.4.1 Measured Hydraulic Capacity 5.4.2 Selection of Hydraulic Loading

Cycle and Application Rate 5.4.3 Other Considerations

5.5 Land Requirements 5.5.1 ~nfiltration Basin Area 5.5.2 Preapplication Treatment

~acilities 5.5.3 Other Land Requirements

5.6 Infiltration System Design 5.6.1 Distribution and Basin Layout 5.6.2 Storage and Flow Equalization 5.6.3 Cold Weather Modifications

5.7 Drainage 5.7.1 Subsurface Drainage to

Surface Waters , 5.7.2 Ground Water Mounding 5.7.3 Underdrains 5.7.4 Wells'

5.8 Monitoring an? Maintenance Requirements 5.8.1 Monitoring 5.8.2 . Maintenance

5.9 Design and Construction Guidance 5.10 References I

I

OVERLAND FLOW PROCESS DESIGN 6.1 Introduction '

6.1.1 Site Characteristics and Evaluation.

6.1.2 Water Quality Requirements 6.1.3 Design and Operating Parameters

6.2 Process Performance 6.2.1 BOD Removal 6.2.2 Suspended Solids Removal 6.2.3 Nitrogen Removal 6.2.4 Phosphorus Removal 6.1.5 Trace Element Removal 6.2.6 Mircroorganism Removal 6.2.7 Trace Organic's Removal 6.2.8 Effect of Rainfall

I I

! viii

CONTENTS (Continued)

Chapter 6.2.9 E:ffect of SlopeGrqde 6.2.10 Performance During Startup Preapplication Treatment, Design Criteria Selection 6.4.1 Hydraulis Loading Rate 6.4.2 Application Rate 6.4.3 Application Period 6.4.4 Application Frequency 6.4.5 Constituent Loading Rates 6.4.6 Slope Length 6.4-7 Slope Grade 6.4.8 Itand Requirements Storage Requirements 6.5.1 Storage Requirements fbr

Cold Weather 6.5.2 Storaqe for Stormwater Runoff 6.5,3 storage for Equalization Distribution 6.6.1 Surface Methods 6.6.2 Low Pressure Sprays 6.6.3 High Pressure Sprinklers 6.6.4 Buried Versus Aboveground Systems 6.6.5 Automation Vegetative Cover 6.7.1 Vegetative dover Function 6.7.2 Vegetative Cover Selection

6.8 Slope Con.struction 6.8.1 System Layout 6.8,2 Grading Operations 6.8-3 Seeding and Crop Establishment

6.9 Runoff Collection 6.10 System Monitoring and Management

6.10.1 Monitoring - 6.10.2 System Management

6.11 Alternative Design Methods 6.11.1 CRREL Method 6.11.2 University of California,

Davis, (UCD) Method 6.11.3 Comparison of Alternative Methods

6.12 References

7 SMALL SYSTEMS 7.1 Introduction 7.2 Facility Planning

7.2.1 Process Considerati~ns 7.2.2 Site Selection 7.2.3 Site Investigations

Page

CONTENTS; (Continued)

Chapter I 7.3 Facility Design

7.3.1 Preapplication Treatment and storage

7.3.2 Hydraulic Loading Rates 7.3.3 Land Area Requirements 7.3.4 Distribution Systems

7.4 Typical Small, Community Systems 7.4.1 Slow Rate Forage System 7.4.2 Slow Rate Forest System 7.4.3 Rapid Infiltration 7.4.4 Overland Flow

7.5 References

8 ENERGY REQUIREMENTS AND CONSERVATION 8.1 Introduction 8.2 Transmission Pumping 8.3 General Process Energy Requirements

8.3.1 Slow Rate 8.3.2 Rapid Infiltration 8.3.3 Overland Flow

8.4 Energy Conservation - 8.4.1 Areas of Potential Energy Savings 8.4.2 Example: Energy Savings in

Slow Rate Design 8.4.3 Summary

8.5 Procedures for Energy Evaluations 8.5.1 Slow Rate 8.5.2 Rapid Infiltration 8.5.3 Overland Flow 8.5.4 Examples

8.6 Equations for Energy Requirements 8.6.1 Preapplication Treatment 8.6.2 Land Treatment Processes

8.7 References ,

9 HEALTH AND ENVIRONMENTAL EFFECTS 9.1 Introduction 9.2 Nitrogen

9.2.1 Crops 9.2.2 Ground Water 9.2.3 Surface Water

9.3 Phosphorus ' 9.3.1 Soils 9.3.2 Crops 9.3.3 Ground Water 9.3.4 Surfacewater

Page 7- 9

CONTENTS (Continued)

Chapter 9.4 Dissolved Solids

9.4.1 Soils 9.4.2 Crops 9.4.3 Ground Water

9.5 Trace Elements 9.5.1 Soils 9.5.2 .Crops 9.5.3 Ground Water

9.6 Microorganisms 9.6.1 Soils 9.6.2 Crops 9.6.3 Ground Water 9.6.4 Surface Water 9.6.5 Aerosols

9.7 Trace Organics 9.7.1 Soils. 9.7.2 Crops 9.7.3 Ground Water 9.7.4 Surface Water

9.8 References

Appendix A SLOW RATE DESIGN EXAMPLE

A. 1 Introduction A.2 Statement of Problem

A. 2.1 Background A.2.2 Population and Wastew9ter

Characteristics A.2.3 Discharge Requirements A.2.4 Site Characteristics A. 2.5 Climate

A.3 Slow Rate System Selection A.3.1 Preapplication ~reatment A.3.2 Crop Selection

A. 4 System Design A.4.1 Forage Crop Alternative A.4.2 Deciduous Forest Crop Alternative A.4.3 Selected SR Design A. 4.4 Energy Requirements

Page

B RAPID INFILTRATION DESIGN EXAMPLE B.l Introduction B- 1 B.2 Design Considerations B- 1

B.2.1 Design Community B- 1 B.2.2 Wastewater Quality and Quantity B- 1 B.2.3 Existing Wastewater

Treatment Facilities B- 2

CONTENTS (Continued) I I

Appendix Page B.2.4 Climate Site and Process Selection Site Investigations B.4.1 SoilCharacteristics B.4.2 Ground Water Characteristics B. 4.3 Hydraulic Capacity Determination of Wastewater Loading Rate B.5.1 Preapplication Treatment Level B.5.2 ~ydraulic Loading Rate B. 5.3 Hydraulic Loading Cycle B.5.4 Effect of Precipitation on

Wastewater Loading Rate B.5.5 Underdrainage B.5.6 Nitrification Land ~e~uirements B.6.1 Preapplication Treatment

Facilities I B.6.2 Infiltration Basins System Design B.7.1 General Requirements B.7.2 Underdrainage Maintenance and Monitoring B.8.1 Maintenance B.8.2 Monitoring System Costs Energy Budget References

C OVERLAND FLOW DESIGN EXAMPLE C. 1 Introduction ~ C-1 C.2 Statement of the Problem C- 1 C.3 Design Considerations C- 1

C.3.1 Wastewater Characteristics and Discharge Requirements C-1

C. 3.2 Climate C- 2 C.4 Site Evaluation and Process Selection C- 2

C.4.1 General Site Characteristics C-2 C. 4.2 Soil Characteristics C-4 C.4.3 Process Selection C- 4

C.5 Distribution Method C- 4 C.6 Preapplication Treatment C- 4 C.7 Wastewater Storage C- 5

C.7.1 Storage Requirement C- 5 C.7.2 Storage Facility Description C- 5

C.8 Selection of Design Parameters C- 6 C.8.1 Hydraulic Loading Rate C- 6 C.8.2 Application Period and Frequency C-6

' xii

CONTENTS (Continued)

Appendix C. 8.3 Slope Length and Grade C.8.4 Application Rate C. 8.5 Land Requirements

C.9 Distribution System C.10 Preliminary System Layout C.11 System Design

C. 11.1 Treatment Slopes C.11.2 Runoff Channel Design C.11.3 Collection Waterways C. 11.4 Pumping System C.11.5 Monitoring and Collection System

C.12 Land Requirements C.13 Cover Crop Selection C.14 System Costs C.15 Energy Budget C.16 Alternative Design Methods -

Design Example C.16.1 CRREL Method C.16.2 University of California,

Davis, Method C.16.3 Comparison of Methods

C. 17 References

D LOCATION OF LAND TREATMENT SYSTEMS D. 1 Slow Rate Systems D.2 Rapid Infiltration Systems ' D.3 Overland Flow Systems

E DISTRIBUTION SYSTEM DESIGN FOR SLOW RATE E. 1 Introduction E.2 General Design Considerations

E. 2.1 Depth of Water Applied E.2.2 Application Frequency E.2.3 Application Rate E.2.4 Application Period E.2.5 Application Zone E. 2.6 System Capacity

E.3 Surface Distribution System E.3.1 Ridge and Furrow Di*stribution E.3.2 Graded Border Distribution

E.4 Sprinkler Distribution Systems E. 4.1 Application Rates E.4.2 Solid Set Sprinkler Systems E.4.3 Move-Stop Sprinkler Systems E.4.4 Continuous Move Systems

E .5 References

Page

xiii

CONTENTS (Concluded)

Appendix F ESTIMATED STORAGE DAYS FOR LAND TREATMENT

USING EPA COMPUTER PROGRAMS

G GLOSSARY OF TERMS 1 CONVERSION FACTORS I

Page

xiv

FIGURES

No. Page

Slow Rate Hydraulic Pathways Rapid Infiltration Hydraulic Pathways Overland Flow Examples of Combined Systems Two-Phase Planning Process Potential Evapotranspiration Versus Mean Annual Precipitation Estimated Design Percolation Rate as a Function of Soil Permeability for SR and RI Land Treatment

Winter Operation of Rapid Infiltration at Lake George, New York

Estimated Wastewater Storage Days Based only on Climatic Factors Total Land Required (Includes Land for Application, Roads, Storage, and Buildings) Example Area of Soil Map to be Evaluated Example Suitability Map for Soils in Figure 2-7 Staffing Requirements for Land Treatment Components (not Including Sewer System or Preapplication Treatment) far Municipally Owned and Operated Systems Dominant Water Rights Doctrines and Areas of Water Surplus or Deficiency Flow Chart of Field Investigations Infiltration Rate as a Function of Time for Several Soils Parosity, Specific Retention, and Specific Yield Variations with Grain Size, South Coastal Basin, California General Relationship Between Specific Yield and Hydraulic Conductivity Typical Pattern of the Changing Moisture Profile During Drying and Drainage Flooding Basin Used for Measuring Infiltration Groove Preparation for Flashing (Berm) ! Schematic of Finished Installation Infiltration Rate and Cumulative Intake Data Plot Cylinder Infiltrometer in Use Layout of Sprinkler Infiltrometer Schematic of Double-Tube Apparatus Schematic of Air-Entry Permeameter Well and Piezometer Installation Vertical Flows Indicated by Piezometers Definition Sketch for Auger-Hole Technique

! . .

FIGURES ! (continued)

Page

Experimental Setup for: Auger-Hole Technique Slow Rate Design Procedure Nitrogen Uptake Versus Growing Days for Annual and Perennial Crops Determination of Storage by EPA Computer Programs According to' Climatic Constraints Surface Distribution Methods Fan Nozzle Used for Spray Application at West Dover, Vermont Solid Set Sprinklers wkth Surface Pipe in a Forest System

Rapid Infiltration Design Procedure Effect of Infiltration Rate on Nitrogen Removal Infiltration Basin Outlet and Splash Pad Interbasin Transfer Structure with Adjustable Weir I Natural Drainage of Renovated Water Into Surface Water '

Example Design for subsurface Flow to Surface Water Schematic of Ground Water Mound Mounding Curve for Center of a Square Recharge Area Mounding Curve for Center of a Rectangular Recharge Area at ~ifferent Ratios of Length (L) to Width (W) Rise and Horizontal Spread of Mound Below a Square Recharge Area Rise and Horizontal Spread of Mound Below a Rectangular Recharge Area Whose Length is Twice its Width I Centrally Located Underdrain Underdrain System Using Alternating Infiltration and Drying Strips

Parameters Used in Drain Design Well Configurations Overland Flow Design ~iocedure Surface Distribution Using Gated Pipe for OF Distribution for OF Using Low Pressure Fan Spray Nozzles Alternative Sprinkler donfigurations for Overland Flow Distribution Land Plane Used for Final Grading Land Area Estimates fon Preliminary Planning Process (Including Land fox Preapplication Treatment) Typical Annual ~~draul+ Loading Rate of Small SR and OF Systems

FIGURES (Concluded) No.

' Page

Typical Annual Hydraulic Loading Rate of Small SR Systems Overflow Control Structure for Pond Discharge to SR System Treatment Facility Layout - Kennett Square, Pennsylvania, SR System SR Facilities at Kennett Square, Pennsylvania Center Pivot System Automatic Surface Irrigation System Soils Map System Layout: Forage Crop Alternative System Layout: Forest Crop Alternative Soils Map, Sites 1 and 2 Ground Water Contours Intake Curves - Infiltration Basin 1 Community B Rapid Infiltration System Flowsheet Community B Site Layout Underdrain Location Proposed Overland Flow Treatment Site Typical Overland Flow Slope Contour Map of Proposed Overland Flow Treatment System Overland Flow System Layout Surface Distribution Methods Aluminum Hydrant and Gated Pipe at Sweetwater, Texas Outlet Valve for Border Strip Application Solid Set Sprinkler System Move-Stop Sprinkler Systems Side Wheel Roll Sprinkler System Continuous Move Sprinkler Systems Hose-Drag Traveling Gun Sprinkler Center Pivot Rig Center Pivot Irrigation System

TABLES

No. Page

Comparison of Typical Design Features for Land Treatment ~roceskes Comparison of Site characteristics for Land Treatment Processes Expected Quality of Treated Water from Land Treatment Processes Important Constituents in Typical Domestic Wastewater Comparison of Trace Elements in Water and Wastewaters Typical BOD Loading Rates National Interim Primary Drinking Water Standards, 1977' Summary of Climatic Analyses Land Use Suitability ~hctors for Identifying Land Treatment Sites Grade Suitability Factors for Identifying Land Treatment Sites Soil Textural Classes and General Terminology Used in Soil Descriptions Typical Soil Permeabilities and Textural Classes for Land Treatment Processes Site Selection Guidelines Rating Factors for Site Selection Characteristics of Soil Series Mapped in Figure 2-7 Example Use of Rating Factors for Site Selection Applicability of Recovery Systems for Renovated Water Lease/Easement Requirements for Construction Grants Program Funding Potential Water Rights Problems for Land Treatment Alternatives Summary of Field Testslfor Land Treatment Processes Comparison of Infiltration -Measurement Techniques Sample Comparison of Infiltration Measurement Using Flooding and Sprinkling Techniques Suggested Vertical Placement of Tensiometers in Basin Infiltrometer Tests

Measured Ratios of Horizontal to Vertical Conductivity, Interpretation of SoillChemical Tests BOD Removal Data for Selected SR Systems Nitrogen Removal Data for Selected SR Systems

I

TABLES (Continued)

No. Page

Phosphorus Removal Data for Typical SR Systems Trace Element Behavior During SR Land Treatment Suggested Maximum Applications of Trace Elements to Soils Without Further Investigations Coliform Data for Several SR Systems Benzene, Chloroform, and Trichloroethylene in Muskegon Wastewater Treatment System

Relative Comparison of Crop Characteristics Summary of Operational Forest Land Treatment Systems in the United States Receiving Municipal Wastewater Height Growth Response of Selected Tree Species Nutrient Uptake Rates for Selected Crops Estimated Net Annual Nitrogen Uptake in the Overstory and Understory Vegetation of Fully Stocked and Vigorously Growing Forest Ecosystems in Selected Regions of the United States Biomass and Nitrogen Distribution by Tree Component for Stands in Temperate Regions Examples of Estimated Monthly Potential Evapotranspiration for Humid and Subhumid Climates Consumptive Water Use and Irrigation Requirements for Selected Crops at San Joaquin Valley, California Summary of Wastewater Constituents Having Potential Adverse Effects Water Balance to Determine Hydraulic Loading Rates Based on Soil Permeability Estimating of Storage Volume Requirements Using Water Balance Calculations Summary of Computer Programs for Determining Storage from Climatic Variables

Final Storage Volume Requirement Calculations Surface Distribution Methods and Conditions of Use Advantages and Disadvantages of Sprinkler Distribution Systems Relative to Surface Distribution Systems Sprinkler System Characteristics Suggested Service Life for Components of Distribution System Recommended Design Factors for Tailwater Return Systems

xix

TABLES (Continued)

No. Page

Approximate Criticall Levels of Nutrients in Soils for Selected Crops in California 4-59

Grazing Rotation cycles for Different Numbers of Pasture Areas 4-62 Recommended Soil Con-tact Pressure 4-67 BOD Removal for Selected RI Systems 5-4 Nitrogen Removal Data for Selected RI Systems 5-5 Phosphorus Removal Data for Selected RI Systems 5-6 Comparison of Trace Element Levels to Irrigation and Drinlting Water Limits 5-7

Heavy Metal Retention in an Infiltration Basin 5-7 Fecal Coliform Removal Data for Selected RI Systems 5-8 Reported Isolations of Virus at RI Sites 5-9 Recorded Trace Organic Concentrations at Selected RI Sites 5-10 Suggested Preapplication Treatment Levels 5- 11 Typical Hydraulic Loading Rates for RI Systems 5-13 Suggested Annual Hydraulic Loading Rates 5-14 Typical Hydraulic Loading Cycles 5-16 Suggested Loading Cycles 5-17 Minimum Number of Basins Required for Continuous Wastewater Application 5-25 OF Design and Operating Parameters 6-3 Summary of Process Operating Parameters, BOD and SS Performance at OF Systems 6- 4 Summary of Nitrogen and Phosphorus Performance at OF Systems 6- 5 Removal Efficienciesof Heavy Metals at Different Hydraulic Rates at Utica, Mississippi 6-9 Overland Flow Design Guidelines 6-12 Types and Sources of Data Required for Design of Small Land Treatment Systems 7-2 General Characteristics of Small Land Treatment Systems 7-3 Typical Staffing Requirements at Small Systems 7-6 Recommended Level of Preapplication Treatment 7-9 Typical Design Parameters for Several Types of Ponds 7-10 Nitrogen Uptake Rates for Selected Crops 7-14 Design Information for SR System 7-19 Design Information for Chapman RI System 7-27 Wastewater Flows to Chapman RI System 7-29 Treatment Performance of Carbondale OF System 7-31 Energy Requirements for Crop Production 8-4 Most Common Unit Energy Requirements for Land Treatment of Mynicipal Wastewater 8 - 5

TABLES (Continued)

No. Page

Example System Characteristics Comparison of Conventional and Automated Ridge and Furrow Systems for 38,000 m3/d Comparison of Impact and Drop-Type Center Pivot System Nozzle Designs on Energy Requirements Total Annual Energy for Typical 3,785 m3/d System Land Treatment Methods and Concerns Relationship of Pollutants to Health Effects EPA Long-Term Effects Studies Tolerance of Selected Crops to Salinity in Irrigation Water

Mass Balance of Trace Elements in OF System at Utica, Mississippi Trace Element Content of Forage Grasses at Selected SR Systems Trace Element Drinking and Irrigation Water Standards Virus Transmission Through Soil at RI Systems Aerosol Bacteria at Land Treatment Sites Aerosol Enteroviruses at Land Treatment Sites Comparison of Coliform Levels in Aerosols at Activated Sludge and Slow Rate Land Treatment Facilities Trace Organics Removals During Sand Filtration Trace Organics Removals at Selected SR Sites Removal of Refractory Volatile Organics by Class at Phoenix RI Site Chloroform and Toluene Removal During OF Population and Wastewater Characteristics Climatic Data for the Worst Year in 5 Hydraulic Loading Rates Based on Soil Permeability: Forage Crop Alternative Design Hydraulic Loading Rate Storage Volume Determination: Forage Crop Alternative Final Determination of Storage Volume Design Criteria for Storage Lagoons: Forage Crop Alternative Slow Rate System Design Data: Forage Crop Alternative Cost Estimate Criteria: Forage Crop Alternative Cost Estimate Calculations: Forage Crop Alternative Summary of Costs: Forage Crop Alternative Initial Determination of Storage Volume: Forage Crop Alternative

xxi

No.

TAB~ES (Concluded) I

Design Data for storAge Pond: Forest Crop Alternative Design Data: ForestlCrop Alternative Summary of Cost: Deciduous Forests Projected Wastewater Characteristics Surface Water Discharge Requirements Average Meteorological Conditions General Soil Characteristics: Sites 1 and 2 Typical Log of Test Hole Ground Water Quality Cost of Community B RI System Raw Wastewater Characteristics Average Meteorological Conditions Storage Requirements Land Requirements Cost of Community C OF System Optimum Furrow Spacing Suggested Maximum Lengths of Cultivated Furrow::; for Different SoilsJ Grades, and Depths of Water to be Applied Design Guidelines for Graded Border Diskribution, Deep Rdoted Crops Design Guidelines for Graded Border Distribution, Shallow Rooted Crops Recommended Reductions in Application Rates Due to Grade Recommended Spacing df Sprinklers Factor (F) by Which Pipe Friction Loss is Multiplied to 0btaid Actual Loss in a Line with Multiple Outlets Recommended Maximum Lane Spacing for Traveling Gun Sprinklers Storage Days Using EPA-1 for 20 Year (5%) and 10 Year (10%) Return Intervals Storage Days Using EPA-2 for 20 Year (5%) and 10 Year (10%) Return Intervals Storage Days Using EPA-3 for 20 Year (5%) and 10 Year (10%) Return Intervals

Page

xxii

CHAPTER 1

INTRODUCTION AND PROCESS CAPABILITIES

1.1 P u r p o s e

The p u r p o s e o f t h i s manual is t o p r o v i d e c r i t e r i a and s u p p o r t i n g i n f o r m a t i o n f o r p l a n n i n g and p r o c e s s d e s i g n o f l a n d t r e a t m e n t s y s t e m s . Recommended p r o c e d u r e s f o r p l a n n i n g and d e s i g n a r e p r e s e n t e d a l o n g w i t h s t a t e - o f - t h e - a r t i n f o r m a t i o n o n t r e a t m e n t p e r f o r m a n c e , e n e r g y c o n s i d e r a t i o n s , and h e a l t h and e n v i r o n m e n t a l e f f e c t s .

C o s t c u r v e s a r e n o t i n c l u d e d i n t h i s manua l , a l t h o u g h some c o s t i n f o r m a t i o n i s i n c l u d e d i n C h a p t e r 2. C o s t s f o r p l a n n i n g may be o b t a i n e d from c o s t c u r v e s i n r e f e r e n c e s [ I r 21 , o r t h r o u g h t h e CAPIIET computer s y s t e m d e v e l o p e d by t h e Corps o f E n g i n e e r s f o r EPA. CAPDET compute r t e r m i n a l s are a v a i l a b l e i n EPA r e g i o n a l o f f ices.

T h i s document i s a r e v i s i o n o f t h e P r o c e s s Des ign Manual f o r Land T r e a t m e n t o f M u n i c i p a l Wastewater s p o n s o r e d by t h e U . S. E n v i r o n m e n t a l p r o t e c t i o n Agency, U . S. Army Corps o f E n g i n e e r s , and U.S. Depar tment o f A g r i c u l t u r e , and p u b l i s h e d i n 1977. The r e v i s i o n is n e c e s s a r y b e c a u s e o f t h e l a r g e amount o f r e s e a r c h d a t a , c r i t e r i a , and o p e r a t i n g e x p e r i e n c e t h a t h a s become a v a i l a b l e i n r e c e n t y e a r s . A s a r e s u l t o f PL 92-500 and PL 95-217, t h e i n t e r e s t i n and u s e of l a n d t r e a t m e n t c o n c e p t s h a s i n c r e a s e d s i g n i f i c a n t l y and is e x p e c t e d t o c o n t i n u e t o i n c r e a s e .

1 . 2 Scope

Land t r e a t m e n t is d e f i n e d as t h e c o n t r o l l e d a p p l i c a t i o n o f wastewater o n t o t h e l a n d s u r f a c e t o a c h i e v e a d e s i g n e d de- g r e e o f t r e a t m e n t t h r o u g h n a t u r a l p h y s i c a l , c h e m i c a l , and b i o l o g i c a l p r o c e s s e s w i t h i n t h e p l a n t - s o i l - w a t e r m a t r i x .

The s c o p e of t h i s manual is l i m i t e d t o t h e t h r e e m a j o r l a n d t r e a t m e n t p r o c e s s e s :

Slow ra te (SR)

Over l and f l o w (OF) These p r o c e s s e s are d e f i n e d l a t e r i n t h i s c h a p t e r and d i s - c u s s e d i n d e t a i l i n t h e d e s i g n c h a p t e r s . The t i t l e s were a d o p t e d f o r t h e o r i g i n a l 1977 manual t o r e f l e c t t h e r a t e o f

wastewater a p p l i c a t i o n {nd t h e f l o w p a t h w i t h i n t h e p r o c e s s . P r i o r t o t h e 19,77 manual , t h e t e r m " i r r i g a t i o n " was o f t e n used t o d e s c r i b e t h e s low ra te p r o c e s s . The pre- s e n t t e r m w a s chosen t o f o c u s a t t e n t i o n on w a s t e w a t e r t rea t - ment r a t h e r t h a n on i r r i g a t i o n o f c r o p s .

S u b s u r f a c e s y s t e m s , w e t l a n d s , and a q u a c u l t u r e were d i s c u s s e d b r i e f l y i n t h e 1977 manual. b u t a r e d e l e t e d h e r e s i n c e t h e y are now c o v e r e d i n d e t a i l i n o t h e r documents [ 3 , 4:l. Land a p p l i c a t i o n o f s l u d g e , i n j e c t i o n w e l l s , e v a p o r a t i o n ponds , and o t h e r forms o f t r e a t m e n t o r d i s p o s a l t h a t i n v o l v e t h e s o i l m a t r i x are a l s o e x c l u d e d .

I

Most of t h e i n f o r m a t i o n i n t h i s manual i s a p p l i c a b l e t o medium-to-large sys t ems . , For s m a l l s y s t e m s , up t o 1 , 0 0 0 m3/d (250,000 . g a l / d ) , many of t h e d e s i g n p r o c e d u r e s c a n b e s i m p l i f i e d . S p e c i a l c o n s i d e r a t i o n s f o r t h e s e s m a l l s y s t e m s and a number o f t y p i c a l examples a r e discixssed i n C h a p t e r 7. Case s t u d i e s f o r l a r g e r sys t ems a r e a v a i l a b l e i n o t h e r p u b l i c a t i o n s [5-91 . T h i s manual a d d r e s s e s l a n d t r e a t m e n t of m u n i c i p a l w a s t e w a t e r , n o t i n d u s t r i a l w a s t e s . Under c o n t r o l l e d c o n d i t i o n s , however, l a n d t r e a t m e n t of many t y p e s of i n d u s t r i a l w a s t e w a t e r s and even h a z a r d o u s m a t e r i a l s c a n be b o t h t e c h n i c a l l y and e c o n o m i c a l l y f e a s i b l e .

Al though t h e p r i n c i p a l f o c u s i n t h e manual is on t h e t h r e e b a s i c p r o c e s s e s (SR, R I , O F ) , t h e p o s s i b i l i t y of clombining two or more o f t h e c o n c e p l t s i n a c o n t i n u o u s systern s h o u l d n o t be o v e r l o o k e d . Over la~nd f low c o u l d be a p r e a p p l i c a t i o n s t e p f o r e i t h e r SR o r R I , o r d i f f e r e n t p r o c e s s e s c o u l d b e used i n c o l d and warm wea the r .

1 .3 Trea tmen t PFocesses

T y p i c a l d e s i g n f e a t u r e s f o r t h e t h r e e l a n d t r e a t m e n t p r o c e s s e s a r e compared i n T a b l e 1-1. The ma jo r s i t e c h a r a c - t e r i s t i c s are compared f o r e a c h p r o c e s s i n T a b l e 1-2. These are d e s i r a b l e c h a r a c t e r i s t i c s and n o t l i m i t s t o be adhe red t o r i g o r o u s l y , as d i s c u s s e d i n C h a p t e r 2.

The e x p e c t e d q u a l i t y of t r e a t e d w a t e r f o r biochemica:L oxygen demand (BOD) , suspended s o l i d s (SS) , n i t r o g e n , phosphorus , and f e c a l c o l i f o r m s is p r e s e n t e d f o r e a c h p r o c e s s i n T a b l e 1-3. The a v e r a g e and e x p e c t e d upper r a n g e va.:Lues are v a l i d f q r t h e t r a v e l d i s t a n c e s and a p p l i e d was teara ter as i n d i c a t e d . The f a t e of1 t h e s e materials ( p l u s m e t a l s , v i r u s e s , and t r a c e o r g a n i c s ) i s d i s c u s s e d i n t h e c h a p t e r s t h a t f o l l o w .

TABLE 1-1 COMPARISON OF TYPICAL DESIGN FEATURES

FOR LAND TREATMENT PROCESSES

Feature Slow rate Rapid infiltration Overland flow

Application techniques Sprinkler Usually surface Sprinkler or or surfacea surf ace

Annual loading rate, m Field area required, hab Typical weekly 1.3-10 loading rate, cm Minimum preapplication Primary Primary Grit removal and treatment provided in sedimentationd sedimentatione comminutione the United States Disposition of Evapotranspiration Mainly Surface runoff and applied wastewater and percolation percolation evapotranspiration

with some percola tion

Need for vegetation Required Optional Required

a. , Includes ridge-and-furrow and border strip. . b. Field area in hectares not including buffer area, roads, or ditches for

3,785 m3/d (1 Mgal/d) flow. c. Range includes raw wastewater to secondary effluent, higher rates for higher

level of preapplication treatment. d. With restricted public access: crops not for direct humai consumption. e. With restricted public access.

Note: See Appendix G for metric conversions.

'TABLE 1-2 COMPARISON OF S I T E CHARACTERISTICS

FOR LAND TREATMENT PROCESSES

Slow rate Rapid infiltration Overland flow

Grade Less than 20% on Not critical; excessive Finish slopes 2-8%a cultivated land; grades require much less than 40% on earthwork noncultivated land

Soil Moderately slow to Rapid (sands, sandy loams) Slow (clays, silts, permeability moderately rapid and soils with

impermeable barriers) Depth to 0.6-1 m (minimum) ' l m during flood cycleb; Not criticalC ground water . 1.5-3 m during drying cycle Climatic Storase of ten None (possibly modify Storage usually needed restrictions needed for cold operation in cold weather) for cold weather

weather and during heavy precipitation

a. Steeper grades might be feasible at reduced hydraulic loadings. b. Underdrains can be used to maintain this level at sites with high ground

water table. c. Impact on ground water should be considered for more permeable soils.

TABLE 1-3 EXPECTED QUALITY OF TREATED WATER

FROM LAND TREATMENT P R O C E S S E S ~ mg/L Unless Otherwise Noted

Slow ?ateb Rapid infiltrationC Overland flowd

upper Upper Upper Constituent Averaqe range Average range Average range

BOD

I R A T I O N

P E R C O L A T l ON

( a ) A P P L I C A T I O N PATHWAY

(b) RECOVERY PATHWAYS '

( c ) S U B S U R F A C E PATHWAY

FIGURE 1-1 SLOW RATE HYDRAULI C PATHWAYS

3 . Water c o n s e r v a t i o n b b y r e p l a c i n g p o t a b l e water w i t h t r e a t e d e f f l u e n t , f o r i r r i g a t i o n

4 . P r e s e r v a t i o n and e n l a r g e m e n t o f g r e e n b e l t s and open s p a c e

When r e q u i r e m e n t s a re v e r y s t r i n g e n t f o r n i t r o g e n , p h o s p h o r u s , BOD, SS, p a t h o g l e n s , metals , and t race o r g a n i c s , t h e y c a n b e m e t u s u a l l y w ~ i t h SR t r e a t m e n t . N i t r o g e n is o f t e n t h e l i m i t i n g f a c t o r I f o r SR d e s i g n b e c a u s e o f EPA d r i n k i n g water l i m i t s o n g round water q u a l i t y . :I:n a r i d r e g i o n s , however , m a i n t a i n i n g c h l o r i d e s and t o t a l d i s s o l v e d s a l t s a t a c c e p t a b l e l e v e l s f o r c r o p p r o d u c t i o n may be l i m i t i n g . Management a p p r p a c h e s t o m e e t t h e s e o b j e c t i v e s w i t h i n t h e SR p r o c e s s are d i s c u s s e d u n d e r t h e t o p i c s (1) wastewater t r e a t m e n t , ( 2 ) a g r i c u l t u r a l s y s t e m s , ( 3 ) t u r f s y s t e m s , and ( 4 ) f o r e s t s y s t e m s .

1 . 4 . 1 . 1 Wastewater T r e a t m e n t I

When t h e p r i m a r y o b j e c t i v e of t h e SR p r o c e s s is t r e a t m e n t , t h e h y d r a u l i c l o a d i n g is u s u a l l y l i m i t e d e i t h e r by t h e hy- d r a u l i c c a p a c i t y o f t h e s o i l o r t h e n i t r o g e n r emova l c a p a c i t y o f t h e s o i l - v e g e t a t i o n m a t r i x . U n d e r d r a i n s a re s o m e t i m e s needed f o r d e v e l o p m e n t o f s i t e s w i t h h i g h g round water t a b l e s , o r whe re p e r c h e d water t a b l e s or impermeable l a y e r s p r e v e n t d e e p p e r c o l a t i o n . P e r e n n i a l g r a s s e s are o f t e n c h o s e n f o r t h e v e g e t a t i o n b e c a u s e o f t h e i r h i g h n i t r o g e n u p t a k e , a l o n g e r wastewater a p p l i c a t i o n s e a s o n , and t h e a v o i d a n c e o f a n n u a l p l a n t i n g and c u l t i v a t i o n . Corn and o t h e r c r o p s w i t h h i g h e r m a r k e t v a l u e s are a l s o grown on s y s t e m s w h e r e t r e a t m e n t is t h e major o b j e c t i v e . Muskegon, M i c h i g a n [ l o ] i s a n o t e d example i n t h e U n i t e d S t a t e s w i t h o v e r 2 ,000 h e c t a r e s ( 5 , 0 0 0 acres) o f c o r n u n d e r c u l t i v a t i o n .

I

1 . 4 . 1 . 2 ~ g r i c u l t h r a l S y s t e m s

I n t h e more a r i d w e s t e r n p d r t i o n s o f t h e U n i t e d S t a t ' e s , t h e water i t s e l f ( n o t t h e n u t r i e n t c o n t e n t ) is t h e m o s t v a l u a b l e component o f t h e wastewater. C r o p s are s e l e c t e d f o r t h e i r maximum m a r k e t p o t e n t i a l and t h e l eas t p o s s i b l e amount o f wastewater needed f o r i r r i g a t i o n . A p p l i c a t i o n ra tes be tween 2 t o 8 cm/wk ( 0 . 8 t o 3 . 1 i n + / w k ) are common. T h i s is enough water t o s a t i s f y c r o p n e e d s ; p l u s a l e a c h i n g r e q u i r e m e n t t o m a i n t a i n a d e s i r e d s a l t b a l a n c e i n t h e root zone .

I n t h e more humid eas t , t h e water component may be c r i t i c a l a t c e r t a i n t i m e s o f t h e y e a r and d u r i n g e x t e n d e d d r o u g h t p e r i o d s , b u t t h e n u t r i e n t s l i n t h e wastewater are t h e m o s t v a l u a b l e component . Sys tqms are d e s i g n e d t o p romote t h e

n u t r i e n t u p t a k e by t h e c r o p and i n c r e a s e y i e l d s . A t Muskegon, M i c h i g a n , f o r example , c o r n y i e l d s i n 1977 were 6 .5 m3/ha ( 7 5 b u s h e l s p e r a c re ) compared t o 5 . 2 m3/ha ( 6 0 b u s h e l s p e r acre) f o r t h e n o n w a s t e w a t e r f a r m i n g i n t h e same area [ l o ] . R e g a r d l e s s of g e o g r a p h i c a l l o c a t i o n , wastewater i r r i g a t i o n c a n b e n e f i t c r o p p r o d u c t i o n by p r o v i d i n g n u t r i e n t s and m o i s t u r e .

1 . 4 . 1 . 3 T u r f S y s t e m s

G o l f c o u r s e s , p a r k s , and o t h e r t u r f e d areas a re used i n many p a r t s o f t h e U n i t e d S t a t e s f o r SR s y s t e m s , t h u s c o n s e r v i n g p o t a b l e water s u p p l i e s . T h e s e areas h a v e c o n s i d e r a b l e p u b l i c access and t h i s r e q u i r e s s t r i c t c o n t r o l o f p a t h o g e n i c o r g a n i s m s . T h i s c o n t r o l c a n b e a c h i e v e d by d i s i n f e c t i o n o r by n a t u r a l p r o c e s s e s i n b i o l o g i c a l t r e a t m e n t ponds o r s t o r a g e ponds .

1 . 4 . 1 . 4 F o r e s t S y s t e m s

Slow r a t e f o r e s t s y s t e m s e x i s t i n many s t a t e s i n c l u d i n g O r e g o n , W a s h i n g t o n , M i c h i g a n , M a r y l a n d , F l o r i d a , G e o r g i a , Vermont , a n d N e w Hampshi re . I n a d d i t i o n , e x p e r i m e n t a l s y s t e m s i n a v a r i e t y o f l o c a t i o n s are b e i n g s t u d i e d e x t e n s i v e l y t o d e t e r m i n e p e r m i s s i b l e l o a d i n g ra tes , r e s p o n s e s o f v a r i o u s t ree s p e c i e s , and e n v i r o n m e n t a l e f f e c t s (see C h a p t e r 4 ) . F o r e s t s o f f e r s e v e r a l a d v a n t a g e s t h a t make them d e s i r a b l e s i t e s f o r l a n d t r e a t m e n t :

1. F o r e s t s o i l s o f t e n e x h i b i t h i g h e r i n f i l t r a t i o n ra tes t h a n a g r i c u l t u r a l s o i l s .

2 . S i t e a c q u i s i t i o n costs f o r f o r e s t l a n d are u s u a l l y lower t h a n s i t e a c q u i s i t i o n costs f o r p r i m e a g r i - c u l t u r a l l a n d .

3 . Dur ing c o l d w e a t h e r , s o i l t e m p e r a t u r e s a re o f t e n h i g h e r i n f o r e s t l a n d s t h a n i n a g r i c u l t u r a l l a n d s .

4 . S y s t e m s c a n b e d e v e l o p e d o n steeper g r a d e s i n t h e f o r e s t as compared t o a g r i c u l t u r a l s i t e s .

The p r i n c i p a l l i m i t a t i o n s t o t h e u s e o f wastewater f o r f o r e s t e d SR s y s t e m s are:

1. Water n e e d s and t o l e r a n c e s o f some e x i s t i n g trees may b e l o w .

2. N i t r o g e n removals a r e r e l a t i v e l y low u n l e s s . young, d e v e l o p i n g f o r e s t s a r e used o r c o n d i t i o n s conducive t o d e n i t r i f i c a t i o n a r e p r e s e n t .

3 . Fixed s p r i n k l e r s , h h i c h a r e e x p e n s i v e , a r e u s u a l l y n e c e s s a r y . I

I

4 . F o r e s t s o i l s may bg rocky o r v e r y sha l low.

1 .4 .2 Trea tment Performance

The SR p r o c e s s is c a p a b l e o producing t h e h i g h e s t d e g r e e of was tewate r t r e a t m e n t of a l l t h e l and t r e a t m e n t sys tems. The q u a l i t y v a l u e s shown i n Tab le 1-3 c a n be expec ted f o r most wel l -des igned and we l l -opera ted sys tems.

O r g a n i c s a r e reduced s u b s t a n t i a l l y by SR l a n d t r e a t m e n t w i t h i n t h e t o p 1 t o 2 cm (0 .4 t o 0.8 i n . ) of s o i l . F i l t r a t i o n and a d s o r p t i o n a r e t h e i n i t i a l s t e p s i n BOD removal , b u t b i o l o g i c a l o x i d a t i o n is t h e u l t i m a t e t r e a t m e n t mechanism. F i l t r a t i o n is t h e major removal mechanism f o r suspended s o l i d s . Res idues remaining a f t e r o x i d a t i o n and t h e i n e r t s o l i d s become p a r t of t h e s o i l m a t r i x .

N i t r o g e n is removed p r i m a r i l l y by c r o p u p t a k e , which v a r i e s w i t h t h e t y p e o f c r o p grown and t h e c r o p y i e l d . TO remove t h e n i t r o g e n e f f e c t i v e l y , I t h e c r o p must be h a r v e s t e d . D e n i t r i f i c a t i o n c a n a l s o be s i g n i f i c a n t , even i f t h e s o i l is i n a n a e r o b i c c o n d i t i o n most of t h e t i m e . O the r n i t r o g e n removal mechanisms i n c l u d e ammonia v o l a t i l i z a t i o n and s t o r a g e i n t h e s o i l . I

Phosphorus is removed from s o l u t i o n by f i x a t i o n p r o c e s s e s i n t h e s o i l , s u c h a s a d s o r p t i o n and chemical p r e c i p i k a t i o n . Removal e f f i c i e n c i e s a r e g e n e r a l l y v e r y h igh f o r SR sys tems and a r e more dependen t on t h e s o i l p r o p e r t i e s t h a n on t h e c o n c e n t r a t i o n of t h e phosphorus a p p l i e d . Residual. phos- p h o r u s c o n c e n t r a t i o n s i n t h e p e r c o l a t e w i l l g e n e r a l l y be less t h a n 0.1 mg/L [ l l ] . A , s m a l l b u t s i g n i f i c a n t p o r t i o n of t h e phosphorus a p p l i e d is t a k e n up and removed w i t h t h e c r o p . I

1 .5 Rapid I n f i l t r a t i o n P r o c e s s

I n R I l a n d t r e a t m e n t , m o s t , o f t h e a p p l i e d was tewate r pe r - colates th rough t h e s o i l , and t h e t r e a t e d e f f l u e n t d r a i n s n a t u r a l l y t o s u r f a c e w a t e r s or j o i n s t h e ground wa te r . The w a s t e w a t e r is a p p l i e d t o modera te ly and h i g h l y permeable s o i l s ( s u c h a s s a n d s and lloamy s a n d s ) , by s p r e a d i n g i n ' b a s i n s o r by s p r i n k l i n g , ' a n d is t r e a t e d a s it t r a v e l s

t h r o u g h t h e s o i l m a t r i x . V e g e t a t i o n is n o t u s u a l l y p l a n n e d , b u t t h e r e are some e x c e p t i o n s , and emergence o f weeds and g r a s s e s u s u a l l y d o e s n o t c a u s e p r o b l e m s .

The s c h e m a t i c v iew i n F i g u r e 1 - 2 ( a ) shows t h e t y p i c a l h y d r a u l i c pa thway f o r r a p i d i n f i l t r a t i o n . A much g r e a t e r p o r t i o n o f t h e a p p l i e d wastewater p e r c o l a t e s t o t h e g round water t h a n w i t h S R l a n d t r e a t m e n t . T h e r e is l i t t l e or no c o n s u m p t i v e u s e by p l a n t s . E v a p o r a t i o n r a n g e s f rom a b o u t 0 .6 m/yr ( 2 f t / y r ) f o r cool r e g i o n s t o 2 m/yr ( 6 f t / y r ) f o r h o t a r i d r e g i o n s . T h i s is u s u a l l y a smal l p e r c e n t a g e o f t h e h y d r a u l i c l o a d i n g ra tes .

I n many cases, r e c o v e r y o f r e n o v a t e d water is a n i n t e g r a l p a r t o f t h e s y s t e m . T h i s c a n be a c c o m p l i s h e d u s i n g unde r - d r a i n s o r w e l l s , a s shown i n F i g u r e 1 - 2 ( b ) . I n some cases, t h e water d r a i n s n a t u r a l l y t o a n a d j a c e n t s u r f a c e water ( F i g u r e 1 - 2 ( c ) ) . Such s y s t e m s c a n p r o v i d e a h i g h e r l e v e l o f t r e a t m e n t t h a n m o s t m e c h a n i c a l s y s t e m s d i s c h a r g i n g t o t h e same s u r f a c e water.

1 . 5 . 1 P r o c e s s O b j e c t i v e s The o b j e c t i v e o f R I is wastewater t r e a t m e n t . U s e s f o r t h e t r e a t e d water c a n i n c l u d e :

1. Ground water r e c h a r g e

2 . Recove ry of r e n o v a t e d water by w e l l s or u n d e r d r a i n s w i t h s u b s e q u e n t r e u s e o r d i s c h a r g e

3 . Recha rge of s u r f a c e streams by i n t e r c e p t i o n o f g r o u n d water

4 . Temporary s t o r a g e o f r e n o v a t e d water i n t h e a q u i f e r

I f g r o u n d water q u a 1 i t . y is b e i n g d e g r a d e d by sa l twa te r i n t r u s i o n , g r o u n d w a t e r r e c h a r g e by R I c a n h e l p t o create a b a r r i e r and p r o t e c t t h e e x i s t i n g f r e s h g round water. I n many cases, t h e major t r e a t m e n t g o a l is c o n v e r s i o n o f ammonia n i t r o g e n t o n i t r a t e n i t r o g e n p r i o r t o d i s c h a r g e t o s u r f ace waters. The 131 p r o c e s s o f f e r s a c o s t - e f f e c t i v e method fo r a c h i e v i n g t h i s g o a l w i t h r e c o v e r y o r r e c h a r g e as d e s c r i b e d i n i t e m s 2 a n d 3 a b o v e . R e t u r n o f t h e r e n o v a t e d water t o t h e s u r f a c e by w e l l s , u n d e r d r a i n s , o r g r o u n d water i n t e r c e p t i o n may b e n e c e s s a r y o r a d v a n t a g e o u s when d i s c h a r g e to a p a r t i c u l a r s u r f a c e water body is c o n t r o l l e d by water r i g h t s , o r when e x i s t i n g g r o u n d water q u a l i t y is n o t compat- i b l e w i t h e x p e c t e d r e n o v a t e d water q u a l i t y . A t P h o e n i x , A r i z o n a , f o r example , r e n o v a t e d water is b e i n g w i t h d r a w n by w e l l s t o allow r e u s e o f t h e water f o r i r r i g a t i o n .

A P P L I E D WASTEWATER

( a ) H Y D R A U L I C P A T H W A Y I

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FLOODIN6 B A S I N S RECOVERKD WATER

I I

U N D E R D R A I N S W E L L S

FLOOD l N Q B A S I N

( c ) N A T U R A L D R A I W A G E I N T O S U R F A C E W A T E R S

FIGURE 1-2 RAPID INF 1 LTRATI ON HYDRAULIC PATHWAYS

1 . 5 . 2 T r e a t m e n t P e r f o r m a n c e

Removals of w a s t e w a t e r c o n s t i t u e n t s by t h e f i l t e r i n g and s t r a i n i n g a c t i o n of t h e s o i l a r e e x c e l l e n t . Suspended s o l i d s , BOD, and f e c a l c o l i f o r m s a r e a l m o s t c o m p l e t e l y removed.

N i t r i f i c a t i o n o f t h e a p p l i e d w a s t e w a t e r is e s s e n t i a l l y com- p l e t e when a p p r o p r i a t e h y d r a u l i c l o a d i n g c y c l e s a r e u s e d . T h u s , f o r c o m m u n i t i e s t h a t have ammonia s t a n d a r d s i n t h e i r d i s c h a r g e r e q u i r e m e n t s , R I c a n p r o v i d e a n e f f e c t i v e way t o meet s u c h s t a n d a r d s .

G e n e r a l l y , n i t r o g e n r emova l a v e r a g e s 50% u n l e s s s p e c i f i c o p e r a t i n g p r o c e d u r e s a r e e s t a b l i s h e d t o maximize d e n i t r i f i - c a t i o n . T h e s e p r o c e d u r e s i n c l u d e o p t i m i z i n g t h e a p p l i c a t i o n c y c l e , r e c y c l i n g t h e p o r t i o n s of t h e r e n o v a t e d w a t e r t h a t c o n t a i n h i g h n i t r a t e c o n c e n t r a t i o n s , r e d u c i n g t h e i n f i l t r a t i o n r a t e , and s u p p l y i n g a n a d d i t i o n a l c a r b o n s o u r c e . Us ing t h e s e p r o c e d u r e s i n s o i l column s t u d i e s , a v e r a g e n i t r o g e n r e m o v a l s o f 8 0 % h a v e been a c h i e v e d . N i t r o g e n r emova l by d e n i t r i f i c a t i o n c a n be s i g n i f i c a n t i f t h e h y d r a u l i c l o a d i n g r a t e is a t t h e mid r a n g e o r below t h e v a l u e s i n T a b l e 1-1 and t h e BOD t o n i t r o g e n r a t i o is 3 o r more.

P h o s p h o r u s r e m o v a l s c a n r a n g e f r o m 70 t o 99%, d e p e n d i n g o n t h e p h y s i c a l and c h e m i c a l c h a r a c t e r i s t i c s o f t h e s o i l . A s w i t h S R s y s t e m s , t h e p r i m a r y r emova l mechanism is a d s o r p t i o n w i t h some c h e m i c a l p r e c i p i t a t i o n , so t h e l o n g - t e r m c a p a c i t y is l i m i t e d b y t h e mass and t h e c h a r a c t e r i s t i c s o f s o i l i n c o n t a c t w i t h t h e w a s t e w a t e r . Removals a r e r e l a t e d a lso t o t h e r e s i d e n c e t i m e o f t h e w a s t e w a t e r i n t h e s o i l , t h e t r a v e l d i s t a n c e , and o t h e r c l imat ic and o p e r a t i n g c o n d i t i o n s .

1 . 6 O v e r l a n d F l o w P r o c e s s

I n OF l a n d t r e a t m e n t , w a s t e w a t e r is a p p l i e d a t t h e u p p e r r e a c h e s of g r a s s c o v e r e d s l o p e s and a l l o w e d t o f l o w o v e r t h e v e g e t a t e d s u r f a c e t o r u n o f f c o l l e c t i o n d i t c h e s . The OF p r o c e s s is b e s t s u i t e d t o s i t e s h a v i n g r e l a t i v e l y imper- meab le s o i l s . However, t h e p r o c e s s h a s b e e n u s e d w i t h s u c c e s s o n m o d e r a t e l y p e r m e a b l e s o i l s w i t h r e l a t i v e l y impe rmeab le s u b s o i l s . The w a s t e w a t e r is r e n o v a t e d by p h y s i c a l , c h e m i c a l , and b i o l o g i c a l means a s it f l o w s i n a t h i n f i l m down t h e l e n g t h o f t h e s l o p e . A s c h e m a t i c view o f OF t r e a t m e n t i s shown i n F i g u r e 1 - 3 ( a ) , and a p i c t o r i a l v iew o f a t y p i c a l s y s t e m is shown i n F i g u r e 1 - 3 ( b ) . A s shown i n F i g u r e 1 - 3 ( a ) , t h e r e is r e l a t i v e l y l i t t l e p e r c o l a t i o n i n v o l v e d e i t h e r b e c a u s e of a n impe rmeab le s o i l or a s u b s u r f a c e b a r r i e r t o p e r c o l a t i o n .

WASTEWATER I GRASS A N D V E G E T A T I V E L I T T E R

E V A P O T R A N S P I R A T I O W

+ P E R C O L A T I O N

( a ) H Y O R A U ~ L I C PATHWAY I

( b ) P I C T O R I A L V I E ~ I O F S P R I N K L E R A P P L I C A T I O N FIGURE 1-3

OVERLAND FLOW ~

I n t e r e s t by m u n i c i p a l i t i e s and d e s i g n e n g i n e e r s h a s s p u r r e d r e s e a r c h and demonstra t : ion p r o j e c t s i n S o u t h C a r o l i n a , N e w Hampsh i r e , M i s s i s s i p p i , Oklahoma, I l l i n o i s , and C a l i f o r n i a . Co ld -wea the r o p e r a t i o n h a s been d e m o n s t r a t e d t h r o u g h s e v e r a l w i n t e r s a t Hanove r , N e w Hampshi re . R a t i o n a l d e s i g n e q u a t i o n s h a v e been d e v e l o p e d b a s e d on r e s e a r c h a t Hanover and a t D a v i s , C a l i f o r n i a .

1 . 6 . 1 P r o c e s s O b j e c t i v e s The o b j e c t i v e s o f OF a r e w a s t e w a t e r t r e a t m e n t a n d , t o a mino r e x t e n t , c r o p p r o d u c t i o n . T r e a t m e n t o b j e c t i v e s may be e i t h e r :

1. To a c h i e v e s e c o n d a r y e f f l u e n t q u a l i t y when a p p l y i n g s c r e e n e d raw w a s t e w a t e r , p r i m a r y e f f l u e n t , o r t r e a t m e n t pond e f f l u e n t .

2 . To a c h i e v e h i g h l e v e l s o f n i t r o g e n , BOD, and SS r e m o v a l s .

T r e a t e d w a t e r is c o l l e c t e d a t t h e toe o f t h e O F s l o p e s and c a n be e i t h e r r e u s e d o r d i s c h a r g e d t o s u r f a c e w a t e r . Over- l a n d f l o w c a n a l s o be u sed f o r t h e p r e s e r v a t i o n o f g r e e n b e l t s .

1 . 6 . 2 T r e a t m e n t P e r f o r m a n c e

B i o l o g i c a l o x i d a t i o n , s e d i m e n t a t i o n , and f i l t r a t i o n a re t h e p r i m a r y r emova l mechanisms f o r o r g a n i c s and s u s p e n d e d s o l i d s .

N i t r o g e n r e m o v a l s a r e a c o m b i n a t i o n o f p l a n t u p t a k e , d e n i t r i f i c a t i o n , and v o l a t i l i z a t i o n of ammonia n i t r o g e n . The dominan t mechanism i n a p a r t i c u l a r s i t u a t i o n w i l l depend o n t h e f o r m s of n i t r o g e n p r e s e n t i n t h e w a s t e w a t e r , t h e amount o f c a r b o n a v a i l a b l e , t h e t e m p e r a t u r e , and t h e r a t e s and s c h e d u l e s of w a s t e w a t e r a p p l i c a t i o n . Pe rmanen t n i t r o g e n r emova l by t h e p l a n t s is o n l y p o s s i b l e i f t h e c r o p is h a r - v e s t e d and removed f rom t h e f i e l d . Ammonia v o l a t i l i z a t i o n c a n be s i g n i f i c a n t i f t h e pH o f t h e w a s t e w a t e r is above 7 . N i t r o g e n r e m o v a l s u s u a l l y r a n g e f rom 7 5 t o 9 0 % w i t h t h e f o r m , o f r u n o f f n i t r o g e n d e p e n d e n t on t e m p e r a t u r e and on a p p l i c a t i o n r a t e s and s c h e d u l e . L e s s r emova l o f n i t r a t e and ammonium may o c c u r d u r i n g c o l d w e a t h e r a s a r e s u l t o f r e d u c e d b i o l o g i c a l a c t i v i t y and l i m i t e d p l a n t u p t a k e .

P h o s p h o r u s is removed by a d s o r p t i o n and p r e c i p i t a t i o n i n e s s e n t i a l l y t h e same manner as w i t h t h e S R and R I me thods . T r e a t m e n t e f f i c i e n c i e s are somewhat l i m i t e d b e c a u s e o f t h e l i m i t e d c o n t a c t be tween t h e w a s t e w a t e r and t h e a d s o r p t i o n

s i t e s w i t h i n t h e s o i l . Phdsphorus r emova l s u s u a l l y r a n g e from 50 t o 7 0 % on a mass b a s i s . I n c r e a s e d r e m o v a l s may b e

> w a t e r o b t a i n e d b y a d d i n g alum or f e ' r r i c c h l o r i d e t o t h e wastc,, j u s t p r i o r t o a p p l i c a t i o n on t h e s l o p e . 1 . 7 Combina t ion Sys t ems

I n a r e a s where e f f l u e n t mus t be v e r y good , o r where a h i g h d e g r e e o f t r e a t m e n t r e l i a b i l i t y must be m a i n t ; ! i n e d , c o m b i n a t i o n s o f l a n d t r e a t m e n t p r o c e s s e s may be d e s i r a b l e . F o r example , e i t h e r a n S R , R I , o r a w e t l a n d s t r e a t m e n t s y s t e m c o u l d f o l l o w a n OF s y s t e m and would r e s u l t i n b e t t e r o v e r a l l t r e a t m e n t t h a n t h e QF a l o n e . I n p a r t i c u l a r , t h e s e c o m b i n a t i o n s c o u l d be used t d improve BOD, su spended s o l i d s , n i t r o g e n , and p h o s p h o r u s r emova l s .

S i m i l a r l y , OF c o u l d be used p r i o r t o R I t o r e d u c e n i tzrogen l e v e l s t o a c c e p t a b l e l e v e l s . T h i s combinatiorn was d e m o n s t r a t e d s u c c e s s f u l l y i n a p i l o t s c a l e s t u d y a t . Ada, Oklahoma, u s i n g s c r e e n e d r a w ) w a s t e w a t e r f o r t h e OF p o r t i o n [121 Rapid i n f i l t r a t i o n may a l s o p r e c e d e SR l a n d t reatment : . . I n t h i s c o m b i n a t i o n , r e n o v a t e d w a t e r q u a l i t y f o l l o w i n g R I is e x p e c t e d t o be h i g h enough t h a t even t h e most r e s t r i c t i v e r e q u i r e m e n t s r e g a r d i n g t h e u s e of r e n o v a t e d w a t e r orr food c r o p s c a n be m e t . A l s o , t h e ground w a t e r a q u i f e r c a n be used t o s to re r e n o v a t e d w a t e r t o c o r r e s p o n d w i t h c r o p i r r i g a t i o n s c h e d u l e s . Some o f t h e s e c o m b i n a t i o n s a r e shown s c h e m a t i c a l l y i n F i g u r e 1-4.

1 . 8 Guide t o I n t e n d e d U s e od t h e Manual

T h i s manual i s o r g a n i z e d s i m i l a r l y t o t h e o r i g i n a l 1977 e d i t i o n e x c e p t t h a t t h e de,sign examples a r e i n c l u d e d a s a p p e n d i x e s . C o m p l e t e l y ney f e a t u r e s i n t h i s manual a r e c h a p t e r s on e n e r g y , and h e a l t h and e n v i r o n m e n t a l e f f e c t s .

C h a p t e r s 2 t h r o u g h 6 f o l l o w , i n s e q u e n c e , a l o g i c a l . p ro - c e d u r e f o r p l a n n i n g and d e s ~ i g n o f l a n d t r e a t m e n t s y s t e m s . The p r o c e d u r e commences (Chap t ' e r 2 ) w i t h s c r e e n i n g of t h e e n t i r e s t u d y a r e a t o i d e n k i f y p o t e n t i a l l a n d t r e a t m e n t sites. The P h a s e 1 p l a n n i n g 'is based on e x i s t i n g i n f o r - m a t i o n and d a t a on l a n d u s e , w a t e r r i g h t s , topog: raphy , s o i l s , and geohydro logy . I p o t e n t i a l l y s u i t a b l e s i t e s e x i s t , t h e P h a s e 2 p l a n n i n p t h e n i n v o l v e s d e t a i l e d s i t e i n v e s t i g a t i o n s ( C h a p t e r 3 ) t o d e t e r m i n e p r o c e s s s u i t a b i l i t y and p r e l i m i n a r y d e s i g n c r i t e r i a ( C h a p t e r s 4 , 5 , and 6). P r o c e s s s e l e c t i o n f o r a p a r t i c u l a r s i t u a t i o n i s ' i n f l u e n c e d by h e a l t h and e n v i r o n m e n t a l i s s u e s ( C h a p t e r 9 ) and by e n e r g y

n e e d s ( C h a p t e r 8 ) . Thus , Phase 2 p l a n n i n g r e q u i r e s t h e u s e of a l l t h e t e c h n i c a l c h a p t e r s i n t h e manual .

I

S m a l l communi t i e s ( u p t o 3 ,500 p o p u l a t i o n ) d o n o t u s u a l l y need t h e same l e v e l o f p l b n n i n g and i n v e s t i g a t i o n t h a t i s e s s e n t i a l f o r l a r g e s y s t e m s . Nor do t h e y a l w a y s need t h e l e v e l of s o p h i s t i c a t i o n t h a t is n o r m a l l y p r o v i d e d , i n terms o f e q u i p m e n t and management p r o c e d u r e s , f o r l a r g e s y s t e m s . P r o c e d u r e s and s h o r t c u t s , t h a t a r e u n i q u e t o s m a l l l a n d t r e a t m e n t s y s t e m s a r e d e s c r i b e d i n C h a p t e r 7 . T y p i c a l examples a r e i n c l u d e d t o i l l u s t r a t e t h e l e v e l of e f f o r t needed i n f i e l d work and de ' s ign .

The f i n a l d e s i g n of a l a n d t r e a t m e n t s y s t e m n e e d s o n l y t o draw on t h e p e r t i n e n t c h a p t e r ( 4 , 5 , o r 6 ) f o r t h e i n t e n d e d p r o c e s s . Some a d d i t i o n a l f i e l d i n v e s t i g a t i o n ( C h a p t e r 3 ) may be n e c e s s a r y t o o p t i m i z e h y d r a u l i c l o a d i n g r a t e s and e n s u r e p r o p e r s u b s u r f a c e f low c o n d i t i o n s . T h e d e s i g n c h a p t e r s d o n o t p r e s e n t c o m p l e t e d e t a i l on t h e ha rdware e pumps, p i p e m a t e r i a l s , s p r i n k l e r r i g s , e t c . ) i n v o l v e d . O t h e r s o u r c e s w i l l be needed f o r t h e s e d e s i g n d e t a i l s . The cost i n f o r m a t i o n i n r e f e r e n c e [l] o r i n t h e CAPDET program is s u i t a b l e f o r p l a n n i n g , compar i son of a l t e r n a t i v e s , and p r e l i m i n a r y d e s i g n o n l y . The? f i n a l c o n s t r u c t i o n cost e s t i m a t e s h o u l d be d e r i v e d i n t h e c o n v e n t i o n a l way ( b y m a t e r i ~ l t a k e - o f f , e t c . ) f rom t h e f i n a l p l a n s .

Append ixes A, B , and C p r o v i d e d e s i g n examples o f SR, R I , and OF and a r e i n t e n d e d t o d e m o n s t r a t e t h e d e s i g n p r o c e d u r e . Energy b u d g e t s hnd costs a r e p r o v i d e d a l o n g w i t h t h e p r o c e s s d e s i g n . ~ p ~ e n d i x D c o n t a i n s a r e p r e s e n t a t i v e l i s t o f c u r r e n t l y o p e r a t i n g m u n i c i p a l ( a l s o f e d e r a l government and s e l e c t e d i n d u s t r i a l ) l a n d t r e a t m e n t s y s t e m s i n t h e U n i t e d S t a t e s .

Appendix E p r o v i d e s i n f o r m a t i o n on d e s i g n i n g i r r i g a t i o n s y s t e m s f o r S R f a c i l i t i e s . The l e v e l o f d e t a i l i n t h i s a p p e n d i x is s u f f i c i e n t t o d e v e l o p p r e l i m i n a r y l a y o u t s and s i z i n g f o r d i s t r i b u t i o n s y s t e m components . Appendix F con- , t a i n s a l is t of communi t i e s f o r which t h e EPA p rog rams t h a t d e t e r m i n e s t o r a g e r e q u i r e m e n t s based on c l i m a t e ' ( S e c t i o n 4 .6 .2 ) have been r u n . The f i n a l appencl ix , G , ' p r o v i d e s a g l o s s a r y of terms and c o n v e r s i o n f a c t o r s f rom metric t o U.S. c u s t o m a r y u n i t s f o r a l l f i g u r e s and t a b l e s .

The d e s i g n a p p r o a c h f o r l a n d t r e a t m e n t h a s been e s s e n t i a l l y e m p i r i c a l , i . e . , o b s e r v a t i o n of s u c c e s s f u l p e r f o r m a n c e f o l l o w e d by d e r i v a t i o n o f c r i t e r i a and m a t h e m a t i c a l e x p r e s s i o n s t h a t d e s c r i b e o v e r a l l p e r f o r m a n c e . E s s e n t i a l l y t h e same a p p r o a c h was used t o d e v e l o p d e s i g n c r i t e r i a f o r

a c t i v a t e d s l u d g e and o t h e r b i o l o g i c a l t r e a t m e n t p r o c e s s e s . The p h y s i c a l , c h e m i c a l , and b i o l o g i c a l r e a c t i o n s and i n t e r a c t i o n s o c c u r r i n g i n a l l t r e a t m e n t p r o c e s s e s a r e q u i t e complex and a re d i f f i c u l t t o d e f i n e m a t h e m a t i c a l l y . Such d e f i n i t i o n is s t i l l e v o l v i n g f o r a c t i v a t e d s l u d g e a s w e l l a s l a n d t r e a t m e n t . A s a r e s u l t , t h e d e s i g n p r o c e d u r e s p r e s e n t e d i n t h i s manual a r e s t i l l c o n s e r v a t i v e and a r e based on s u c c e s s f u l o p e r a t i n g e x p e r i e n c e .

More r a t i o n a l d e s i g n p r o c e d u r e s however , a r e becoming a v a i l a b l e (see S e c t i o n 6 . 1 1 ) . I n a d d i t i o n , t h e r e a r e m a t h e m a t i c a l mode l s a v a . i l a b l e t h a t may be used t o e v a l u a t e t h e r e s p o n s e t o a p a r t i c u l a r c o n s t i t u e n t ( n i t r o g e n , p h o s p h o r u s , e t c . ) o r used i n c o m b i n a t i o n t o d e s c r i b e t h e e n t i r e s y s t e m p e r f o r m a n c e . A b r i e f summary o f mode l s t h a t a r e c u r r e n t l y a v a i l a b l e is i n c l u d e d i n r e f e r e n c e [ 1 3 ] . A more d e t a i l e d d i s c u s s i o n o f s p e c i f i c mode l s f o r l a n d t r e a t m e n t c a n be found i n r e f e r e n c e [ 1 4 ] .

1 . 9 R e f e r e n c e s

1. Reed, S.C., e t a l . Cost o f Land T r e a t m e n t Sys t ems . U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency. EPA-430/9-75-003, MCD 10 . Sep tember 1979 .

2. Culp/Wesner/Culp. Water Reuse and R e c y c l i n g . V o l . 2 . U.S.D. I . OWRT/RU-7!3/2. 1979.

3 . U . S . E n v i r o n m e n t a l P r o t e c t i o n Agency. A q u a c u l t u r e Sys t ems f o r Was tewa te r T r e a t m e n t : Semina r P r o c e e d i n g s and E n g i n e e r i n g Asses smen t . Off ice o f Water Program O p e r a t i o n s . EPA-430/9-80-006, MCD 67. Sep tember 1979 .

4. U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency. Des ign Manual f o r O n s i t e Wastewater T r e a t m e p t and D i s p o s a l Sys t ems . C e n t e r o f E n v i r o n m e n t a l R e s e a r c h I n f o r m a t i o n . EPA- 645/1-80-012. O c t o b e r 1980.

5. U . S . E n v i r o n m e n t a l P r o t e c t i o n Agency. Slow R a t e Land T r e a t m e n t : A R e c y c l e Technology . O f f i c e o f Water Pro- gram O p e r a t i o n s . EPA-430/9-80-Olla, MCD 70. O c t o b e r 1980.

6. U. S. E n v i r o n m e n t a l P r o t e c t i o n Agency. Rapid I n f i l t r a - t i o n Land T r e a t m e n t : A R e c y c l e Technology . O f f i c e o f Water Program O p e r a t i o n s . EPA-430/9-80-Ollb, MCD 71. ( I n P r e s s ) 1981.

7 . P r o c e e d i n g s o f t h e I n t e r n a t i o n a l Symposium ,on Land T r e a t m e n t o f Wastewate~. Volumes 1 and 2. Hanove r , N e w Hampsh i r e . Augus t 20-25, 1978 .

8. H i n r i c h s , D . J . , e t a l . , A s s e s s m e n t o f C u r r e n t I n fo rma- t i o n o n O v e r l a n d Flow T r e a t m e n t . U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency. ' O f f i c e o f Wa te r Program O p e r a t i o n s . EPA-430/9-80-002, MCD 66 . S e p t e m b e r 1980 .

I 9 . L e a c h , L.E. , C.G. E n f i b l d , a n d C.C . H a r l i n , Jr. Summary

o f Long-Term Rap id I n f i l t r a t i o n Sys tem S t u d i e s . U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency. O f f i c e o f R e s e a r c h and Deve lopment . Ada, Oklahoma. EPA-600/2-80-165. J u l y 1980 .

10 . W a l k e r , J . M . Was t ewa td r : Is Muskegon C o u n t y ' s l i jo lu t ion Your S o l u t i o n ? u .S. I ~ n v i r o n m e n t a l P r o t e c t i o n Agency. EPA-905/2-76-004, MCD-3'4. Augus t 1979 .

11. J e n k i n s , T.F. a n d A . J . P a l a z z o . W a s t e w a t e r T r e a t m e n t by a Slow R a t e Land T r e a t m e n t Sys tem. U.S. Army C o r p s o f E n g i n e e r s , Cold R e g i o n s R e s e a r c h and E n g i n e e r i n g L a b o r a t o r y . CRREL R e p o r t 81-14. Hanove r , N e w Hampshi re . A u g u s t 1981 .

1 2 . Thomas, R . E . , e t a l . q e a s i b i l i t y o f O v e r l a n d Flow f o r T r e a t m e n t o f Raw D o m e s t i c Wastewater. U . S. E n v i r o n m e n t a l P r o t e c t i o l n Agency. EPA-66/2-74-08,?. 1974 .

1 3 . I s k a n d a r , I . K . Overvie 'w o n Model ing Wastewater R e n o v a t i o n by Land T r e a t m e n t . USACRREL, S p e c i a l R e p o r t . USACRREL, Hanove r , N e w Hampshi re . 1981 .

14 . I s k a n d a r , I . K . ( e d . ) . Mode l i ng Wastewater R e n o v a t i o n : Land T r e a t m e n t . W i l e y I n t e r s c i e n c e , N e w York. 1981 .

CHAPTER 2

PLANNING AND TECHNICAL ASSESSMENT

2 . 1 P l a n n i n g P r o c e d u r e

A d e q u a t e p l a n n i n g mus t p r e c e d e a n y wastewater t r e a t m e n t s y s t e m d e s i g n t o e n s u r e s e l e c t i o n of t h e most c o s t - e f f e c t i v e p r o c e s s t h a t is f e a s i b l e f o r t h e s i t u a t i o n u n d e r c o n s i d e r - a t i o n . I n many cases, g u i d e l i n e s o r s p e c i f i c a t i o n s f o r t h e p l a n n i n g p r o c e d u r e are p r o v i d e d b y t h e a g e n c y r e s p o n s i b l e for t h e p r o j e c t . The p u r p o s e o f t h i s c h a p t e r is to p r e s e n t t h o s e a s p e c t s o f t h e p l a n n i n g p r o c e d u r e t h a t are e i t h e r u n i q u e o r r e q u i r e s p e c i a l e m p h a s i s b e c a u s e o f l a n d t r e a t m e n t .

P r o c e s s s e l e c t i o n f o r l a n d t r e a t m e n t s y s t e m s is more depen- d e n t o n s i t e c o n d i t i o n s t h a n are m e c h a n i c a l t r e a t m e n t a l t e r - n a t i v e s . T h i s c a n mean t h a t t h e r e is a need f o r e x t e n s i v e a n d , i n some cases, e x p e n s i v e s i t e i n v e s t i g a t i o n and f i e l d t e s t i n g p r o g r a m s . To a v o i d u n n e c e s s a r y e f f o r t and e x p e n s e , a two-phase p l a n n i n g a p p r o a c h h a s b e e n d e v e l o p e d and a d o p t e d by most a g e n c i e s c o n c e r n e d . A s shown i n F i g u r e 2-1, P h a s e 1 i n v o l v e s i d e n t i f i c a t i o n o f p o t e n t i a l s i t e s v i a s c r e e n i n g o f a v a i l a b l e i n f o r m a t i o n and e x p e r i e n c e . I f p o t e n t i a l s i t e s f o r a n y o f t h e l a n d t r e a t m e n t p r o c e s s e s a re i d e n t i f i e d , t h e s t u d y moves i n t o P h a s e 2. T h i s p h a s e i n c l u d e s f i e l d i n v e s - t i g a t i o n s and a n e v a l u a t i o n o f t h e a l t e r n a t i v e s .

2 .2 P h a s e 1 P l a n n i n g

E a r l y d u r i n g P h a s e 1, b a s i c d a t a t h a t are common t o a l l wastewater t r e a t m e n t a l t e r n a t i v e s m u s t b e c o l l e c t e d a n d a n a l y z e d a l o n g w i t h l a n d t r e a t m e n t s y s t e m r e q u i r e m e n t s t o d e t e r m i n e w h e t h e r l a n d t r e a t m e n t is a f e a s i b l e c o n c e p t . I f n o l i m i t i n g f a c t o r s a re i d e n t i f i e d t h a t would e l i m i n a t e l a n d t r e a t m e n t f r o m f u r t h e r c o n s i d e r a t i o n , t h e n e x t s t e p s are t o i d e n t i f y p o t e n t i a l l a n d t r e a t m e n t s i t e s and t o e v a l u a t e t h e f e a s i b i l i t y o f e a c h s i t e .

2 .2 .1 P r e l i m i n a r y D a t a

S e r v i c e area d e f i n i t i o n , p o p u l a t i o n f o r e c a s t s , wastewater q u a l i t y and q u a n t i t y p r o j e c t i o n s , a n d water q u a l i t y r e q u i r e - m e n t s are u s u a l l y e i t h e r s p e c i f i e d or d e t e r m i n e d u s i n g p r o c e d u r e s e s t a b l i s h e d b y t h e r e s p o n s i b l e a u t h o r i t y . Wi th t h e e x c e p t i o n o f water q u a l i t y r e q u i r e m e n t s , t h e d a t a are g e n e r a l l y t h e same f o r a l l fo rms o f wastewater t rea tmel ,~ . A few a s p e c t s are s p e c i f i c t o l a n d t r e a t m e n t and are d i s c u s s e d i n t h i s s e c t i o n .

E S T I M A T I O N OF LAND

PHASE 1 I I

I t- LAND TREATMENT S I T E I O E N T l F l C A T l O N NOT F E A S I B L E BECAUSE OF L I M I T I N G FACTORS OR PROJECT REQU IREUENTS

4 t i LAND A P P L I C A T I O N

NOT F E A S I B L E I F THERE ARE NO

I P O T E N T I A L S I T E S ,-

1-1

PHASE 2

F I E L D l N V E S T l 6 A T l O N S

P R E L I M INA'RY DES I GN C R I T E R I A ~ N D COSTS

L A N 0 A P P L l C A T I O N NOT F E A S I B L E FOR

PLAN SELECT l ON OTHEd REASONS OR OTHER A L T E R N A T I V E S MORE COST E F F E C T I V E

I N I T I A T I O N OF LAND TREATMEHT D E S I G N

FIGURE 2-1 TWO-PHASE PLANN l NG PROCESS

I

2 . 2 . 1 . 1 Wastewater Q u a l i t y and L o a d i n g s Ma jo r c o n s t i t u e n t s i n d o m e s t i c wastewater are p r e s e n t e d i n T a b l e 2-1. T r a c e e l e m e n t c o n c e n t r a t i o n r a n g e s are shown i n T a b l e 2-2. The v a l u e s i n t h e s e t a b l e s may b e u s e d f o r pl 'an- n i n g p u r p o s e s when a c o m m u n i t y l s water q u a l i t y h a s n o t b e e n d e t e r m i n e d . O t h e r i m p o r t a n t p a r a m e t e r s i n l a n d t r e a t m e n t d e s i g n c a n i n c l u d e t o t a l d i s s o l v e d s o l i d s , pH, p o t a s s i u m , sod ium, c a l c i u m , magnesium, b o r o n , b a r i u m , s e l e n i u m , f l u o r - i d e , and s i l v e r .

TABLE 2-1 IMPORTANT CONSTITUENTS I N TYPICAL

DOMESTIC WASTEWATER [ I ] mg/L

Type of wastewater

Constituent Strong Medium Weak

BOD 400 220 110 Suspended solids 350 220 100 Nitrogen (total as N) 8 5 40 2 0

Organic 35 15 8 Ammonia 50 25 12 Nitrate 0 0 0

Phosphorus (total as PI 15 8 4 Organic 5 3 1 Inorganic 10 5 3

Total organic carbon 290 160 80

F o r m u n i c i p a l l a n d t r e a t m e n t s y s t e m s , BOD and s u s p e n d e d s o l i d s l o a d i n g s s e ldom l i m i t s y s t e m c a p a c i t y . T y p i c a l BOD l o a d i n g r a tes a t m u n i c i p a l s y s t e m s are shown i n T a b l e 2-3 and are much lower t h a n ra tes used s u c c e s s f u l l y i n l a n d t r e a t m e n t o f f o o d p r o c e s s i n g wastewaters. Suspended s o l i d s l o a d i n g s a t t h e s e i n d u s t r i a l s y s t e m s would b e s imi la r t o t h e BOD l o a d i n g s shown i n T a b l e 2-3.

I n c o n t r a s t , i f n i t r o g e n r emova l is r e q u i r e d , n i t r o g e n l o a d - i n g may l i m i t t h e s y s t e m c a p a c i t y . N i t r o g e n r e m o v a l c a p a c i t y d e p e n d s o n t h e c r o p grown, i f a n y , and o n s y s t e m management p r a c t i c e s . The e n g i n e e r s h o u l d c o n s u l t S e c t i o n s 4 .5 and 5 .4 .3 .1 t o d e t e r m i n e w h e t h e r n i t r o g e n l o a d i n g w i l l g o v e r n s y s t e m c a p a c i t y a n d , t h e r e f o r e , l a n d area r e q u i r e m e n t s .

TABLE 2-2 COMPARISON OF TRACE ELEMENTS IN

WATER AND WASTEWATERS mg/L I

Maximum recommended EPA recommended Untreated concentrations f r drinking

Element wastewatera / irrigation waterg water standardsC Arsenic Boron Cadmium Chromium Copper Iron

Lead Manganese Mercury Nickel Zinc

0.1 0.5-2.0 0.01 0.1 0.2 5.0 5.0 0.2

NO standard 0.2 2.0

0.05 NO standard

0.01 0.05 1.0 0.3 0.05 0.05 0.002

No standard 5.0

a. The concentrations presented encompass the range of values reported in references [2-61.

b. Based on unlimited irrigation.at 1.0 m/yr(3 ft/yr). c. Reference I71 :

TABLE 2-3 TYPICAL BOD LOADING RATES

kg/ha yr

Slow rate Rapid infiltration overland flow -

Range for municipal wastewater 370-1;830 8,000-46,000 2,000-7,500

Note: See Appendix G for metric conversions.

In some cases, other wastewater constituents such as phos- phorus or trace elements may control design. For example, if wastewater trace element concentrations exceed t:.he maxi- mum recommended concentrations for irrigation water (Table 2-2), SR systems may be infeasible or may require special precautions. This is rare, however, and most atunicipal systems will be limited either by hydraulic capacity or nitrogen loading.

2.2.1.2 Water Quality Requirements

Land treatment systems , have somewhat unique discharge requirements because man$ of these systems do not have

c o n v e n t i o n a l p o i n t d i s c h a r g e s t o r e c e i v i n g s u r f a c e waters. I n t h e p a s t , t h e a b i l i t y of t h e s o i l t o t r e a t w a s t e w a t e r was n o t w e l l r e c o g n i z e d . A s a r e s u l t , d i s c h a r g e s t a n d a r d s were o f t e n imposed on a w a s t e w a t e r p r i o r t o i t s a p p l i c a t i o n o n l a n d , t h e r e b y i n c r e a s i n g t r e a t m e n t costs and e n e r g y r e q u i r e - men t s w i t h o u t s i g n i f i c a n t l y improv ing o v e r a l l t r e a t m e n t p e r f o r m a n c e . More r e c e n t l y , l a n d h a s been r e c o g n i z e d a s a n i m p o r t a n t component i n t h e t r e a t m e n t p r o c e s s . F o r t h i s r e a s o n , d i s c h a r g e r e q u i r e m e n t s now a p p l y t o w a t e r q u a l i t y f o l l o w i n g l a n d t r e a t m e n t .

F o r s y s t e m s t h a t d i s c h a r g e t o r e c e i v i n g w a t e r s , s u c h as OF s y s t e m s and some u n d e r d r a i n e d or n a t u r a l l y d r a i n i n g SR and R I s y s t e m s , r e n o v a t e d w a t e r q u a l i t y mus t m e e t s u r f a c e d i s - c h a r g e r e q u i r e m e n t s . F o r s y s t e m s where t h e r e n o v a t e d w a t e r r e m a i n s u n d e r g r o u n d , EPA h a s e s t a b l i s h e d g u i d a n c e f o r t h r e e c a t e g o r i e s of g round w a t e r d i s c h a r g e t h a t meet t h e c r i t e r i a f o r b e s t p r a c t i c a b l e waste t r e a t m e n t . These t h r e e c a t e g o r i e s are as f o l l o w s :

Case 1 - The ground w a t e r c a n p o t e n t i a l l y be used f o r d r i n k i n g water s u p p l y .

The c h e m i c a l and p e s t i c i d e l e v e l s i n T a b l e 2-4 s h o u l d n o t be exceeded i n t h e ground water. I f t h e e x i s t i n g c o n c e n t r a t i o n i n t h e ground w a t e r o f a n i n d i v i d u a l p a r a m e t e r e x c e e d s t h e s t a n d a r d s , t h e r e s h o u l d be no f u r t h e r i n c r e a s e i n t h e c o n c e n t r a t i o n of t h a t parameter r e s u l t i n g f r o m l a n d a p p l i c a t i o n o f w a s t e w a t e r .

C a s e 2 - The g round water is used f o r d r i n k i n g water s u p p l y .

The same c r i t e r i a as ,Case 1 a p p l y and t h e bacterio- l o g i c a l q u a l i t y c r i t e r i o n f rom T a b l e 2-4 a lso a p p l i e s i n c a s e s where t h e ground water is used w i t h o u t d i s i n f e c t i o n .

Case 3 - U s e s o t h e r t h a n d r i n k i n g water s u p p l y . b

Ground water c r i t e r i a s h o u l d be e s t a b l i s h e d by t h e R e g i o n a l A d m i n i s t r a t o r i n c o n j u n c t i o n w i t h app ro - p r i a t e s t a t e a g e n c i e s based on t h e p r e s e n t or p o t e n t i a l u s e of t h e ground water.

F o r e a c h g round water c a t e g o r y , d i s c h a r g e r e q u i r e m e n t s mus t be m e t a t t h e bounda ry of t h e l a n d t r e a t m e n t p r o j e c t .

T#BLE 2-4 NATIONAL INTERIM PRIMARY

DRINKING WATER STANDARDS, 1977 [7,8]

Constituent Reason or characteristic valuea for standard

Physical Turbidity, units lb

Chemical, mg/L Arsenic 0.05 Barium 1.0 Cadmium 0.01 Chromium 0.05 Fluoride 1 1.4-2.4C Lead 0.05 Mercury 0.002 Nitrates as N 10 Selenium 0.01 Silver 0.05 sodiumd --

Bacteriological Total coliforms, MPN/100 mL , 1

Pesticides, mg/L Endrin 0.0002 Lindane 0.004 Methoxychlor 0.1 Toxaphene 0.005 2,4-D I 0.1 2,4,5-TP 0.01

Aesthetic

Health Health Health Health Health Health Health Health Health Cosmetic Health

Disease

Health Health Health Health Health Health

a. The latest revisions to the constituents and concentrations should be used.

b. Five mg/L of suspended solids may be substituted if it can be demonstrated that it does not interfere with disinfection. ;

c. Dependent on ambi.ent air temperature; higher limits for lower temperatures.

d. Ground water dripking supplies must be monitored at least once every 3 years; surface water supplies must be monitored at least annually.

For SR systems, individual states of ten have additional, crop-specific preapplication treatment requirements, These requirements are usually based on the method of wastewater application, the degree of public contact with the site, and the disposition of the crop. For example, crops for human consumption generally require higher levels of prleappli- cation treatment than forage crops.

I

Local and state water quality requirements may also apply to site runoff. Generally, al,l wastewater runoff must be con- tained onsite and reapplied or treated. Stormwater runoff requirements will vary from site to site and will depend on

t h e e x p e c t e d q u a l i t y o f t h e r u n o f f and t h e q u a l i t y o f local s u r f ace waters. S t a t e and l oca l water q u a l i t y a g e n c i e s s h o u l d b e c o n t a c t e d f o r more s p e c i f i c r e q u i r e m e n t s .

2 .2 .1 .3 R e g i o n a l C h a r a c t e r i s t i c s

C r i t i c a l r e g i o n a l p a r a m e t e r s i n c l u d e c l imate , s u r f ace water h y d r o l o g y and q u a l i t y , and g r o u n d water q u a l i t y .

, C l i m a t e i , L o c a l c l imate may a f f e c t (1) t h e water b a l a n c e ( a n d t h u s t h e

a c c e p t a b l e wastewater h y d r a u l i c l o a d i n g r a t e ) , ( 2 ) t h e l e n g t h o f t h e g rowing s e a s o n , ( 3 ) t h e number o f d a y s p e r y e a r t h a t a l a n d t r e a t m e n t s y s t e m c a n n o t be o p e r a t e d , (4) t h e s t o r a g e c a p a c i t y r e q u i r e m e n t , ( 5 ) t h e l o a d i n g c y c l e o f R I s y s t e m s , and ( 6 ) t h e amount o f s t o r m w a t e r r u n o f f . F o r t h i s r e a s o n , loca l p r e c i p i t a t i o n , e v a p o t r a n s p i r a t i o n , t e m p e r a t u r e , and wind v a l u e s m u s t be d e t e r m i n e d b e f o r e d e s i g n c r i t e r i a c a n b e e s t a b l i s h e d . Whenever p o s s i b l e , a t l e a s t 1 0 y e a r s of d a t a s h o u l d b e u s e d to o b t a i n t h e s e v a l u e s .

T h r e e p u b l i c a t i o n s o f The N a t i o n a l O c e a n i c and A t m o s p h e r