RECEIVED

FEB08 1998

ENSR Consulting and Engineering

Letter of Transmittal

ATTENTION

Darrell Sommerhauser

DATE

February 7 1996

PROJECT REFERENCE

Colorado Avenue Subsite

PROJECT NUMBER

2340003 142

WE ARE SENDING YOU THE FOLLOWING

NO ORIG I NO COPIES

1

DESCRIPTION

Revised Downgradient Monitoring Well Installation Work Plan

REMARKS

Mr Sommerhauser

The revised Downgradient Monitoring Well Installation Work Plan is attached If you have anyquestions please call me at (412) 261 2910 Thank you

John Fulton

SIGNATURE

-rrr

One Chatham Center Suite 900112 Washington PlacePittsburgh PA 15219

(412) 261 2910

2014046

CAR3174

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ENCR

Colorado Avenue SubsiteHastings GroundwaterContamination Superfund Site

Hastings, Nebraska

Downgradient MonitoringWell Installation Work Plan

ENSR Consulting and Engineering

1February 1996

Document Number 2340-003-142

CAR3175

ENSR

1

1

1

1

1

1

CONTENTS

• 1 0 INTRODUCTION 1 1m 1 1 Purpose 1 1

9 20 WELL INSTALLATION AND SAMPLING PROGRAM 2 12 1 Proposed Well Locations 2 122 Monitoring Well Installation Procedures and Methodologies 2 2

I30 SCHEDULE 27

IAPPENDICES

Appendix A Stepwise Procedures for Using the Interval Packer Sampler

I

R \REPORTS\2340003 142 |

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LIST OF FIGURES

1 Water Table Surface Elevation October 1995 2 32 Piezometnc Surface Deep Monitoring Wells October 1995 233 Proposed Well Construction Details for BW 91 and BW 9D 244 Proposed Well Construction Details for BW 10 and BW 11 255 Proposed Downgradient Monitoring Well Installation Schedule 3 2

I

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fl \REPORTS\2340003 142 ||| -,1CAR-31

2 0 WELL INSTALLATION AND SAMPLING PROGRAM

The well installation program consists of installing four downgradient monitoring wellsGroundwater samples will also be collected from the four proposed wells during the semi annualgroundwater sampling event The following sections detail monitoring well locations wellinstallation procedures and methodologies

21 Proposed Well Locations

Groundwater monitoring well locations and groundwater flow direction within the shallow anddeep portions of the surficial aquifer are illustrated in Figures 1 and 2

BW 9I/9D Proposed monitoring wells BW 91/9D which will be screened from approximately 160to 170 and 190 to 200 feet below the ground surface will be installed adjacent to GS 13 WellGS 13 is located south of the Thomson Oil Company on Good Samaritan Village property andwas installed by the State of Nebraska as part of the State s response to a leaking undergroundstorage tank

BW 9I/9D will act as the intermediate and deep monitoring well complement to GS 13 Datagenerated from BW 9I/9D will be used to assess the extent of VOC migration east of Elm Streetand to assist in delineating the 290//g/l isoconcentratlon contour which will be used to establishthe area of treatment described in the SOW page 2 paragraph 2

BW 10 and BW 11 Proposed monitoring wells BW 10 and BW 11 which will be screened fromapproximately 120 feet to 200 feet below the ground surface will be installed to evaluate thetransport of VOCs associated with other potential source areas east of Elm Street as well asprovide groundwater chemistry and elevation data to fulfill the requirement for downgradientcompliance monitoring The well design utilizes an extended well screen and was previouslyapproved by the U S EPA in their letter dated October 27 1993

The monitoring wells which are referred to as downgradient compliance wells are located in agenerally north to south line and are aligned perpendicular to the direction of groundwater flowAll are located approximately 800 feet east of Elm Street and are being installed to demonstratethe long term effectiveness of the interim remedy

Monitoring well construction details for wells BW 9I/9D and BW 10 and BW 11 are presented asFigures 2 and 3 respectively

R \REPORTS\23*0003 142 21 C

__________________________ EtKR2 2 Monitoring Well Installation Procedures and Methodologies

In general the procedures and methodologies outlined in the Sampling and Analysis Plan (SAP)which was approved in December 1993 will be used as the guidance document for thisinvestigation Modifications to the procedures specified in the SAP are presented below

• BW 9I/9D will be constructed of 2 inch diameter PVC riser and stainless steel wellscreen whereas BW 10 and BW 11 will be constructed of 4 inch diameter PVC riserand stainless steel well screen The procedures for installing and constructingBW 9I/9D will be similar to those described in Section 3 3 1 of the Mass RemovalPerformance Well and Pump Test Well Installation Report (ENSR Document No2340003/135 June 1994)

• The well screens associated with BW 9I/9D will be installed so that the deep screenextends from 190 to 200 feet and the intermediate screen extends from 160 to 170 feet

• The well screen associated with BW 10 and BW 11 will be installed so that the bottomof the screen extends from approximately the top of clay (200 feet) to approximatelyseven feet above the static water table surface (120 feet) using the procedures outlinedin the SAP

• Each borehole will be advanced to the water table surface Split spoon samples will becollected at 10 feet intervals from the water table surface to a depth of approximately200 feet Soil samples will be collected only for lithologic purposes

• In wells BW 10 and BW 11 groundwater sampling will be conducted using a 5 footinterval packer system to allow for discrete sampling Stepwise procedures for utilizingthe packer system are presented in Appendix A

Table 1 lists the procedures and methodologies which will be utilized during the investigation

R \REPOHTS\2340003 1*2 22CARS 180

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IIIIIII

11I

1 0 INTRODUCTION

The Downgradlent Monitoring Well installation Work Plan (Work Plan) is prepared on behalf ofthe Dravo Corporation {DravoJ and fulfills paragraph 50 (d) (f) of the March 1993 UnilateralAdministrative Order (UAO) Docket No VII 93 F0019 Statement of Work (SOW) and the U SEnvironmental Protection Agency s (EPAs) March 22 and May 12 1995 letters The UAO whichwas issued by the EPA required that a Groundwater Remedial Design/Remedial Action (RD/RA)Program for the Colorado Avenue Subsite (Subsrte) Hastings Nebraska be developed

11 Purpose

Data generated from the downgradient monitoring wells will be used to 1) assess the effects ofmass removal and containment of volatile organic compounds (VOCs) in the groundwaterbeneath the Subsite and 2) evaluate the potential impacts of VOCs on groundwater from othersource areas This Work Plan addresses the following

• a schedule for installing and sampling the downgradtent monitoring wells

• proposed well locations and

• methods and procedures associated with monitoring well installation

R\BEPORTSV2340003 142 1 1C A R j I S l

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— 2 DIA STAINLESS STEELWELL SCREEN (>

12 DIAMETER HOLE

(a) The screen length may vary with well location and shall be determinedby the field geologist

FIGURE 3PROPOSED WELL CONSTRUCTION DETAILS FOR BW-9I/9D

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FIGURE 4PROPOSED WELL CONSTRUCTION DETAILS FOR BW-10 AND BW-11

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IIIIIII

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TABLE 1

Procedures and Methodologies

Actwrty

Drilling Procedures

Soil Sampling Procedures

Total Organic Volatile Screening Procedures

Health & Safety Air Monitoring

Monitoring Well Installation Procedures

Monitoring Well Development Procedures

Groundwater Elevation Data

Well Labeling

Groundwater Quality Sampling

QA/QC Samples

Field Equipment Calibration

Decontamination Procedures

Sample Handling Requirements

Documentation

Sampling Packing & Shipping

Section of the SAP1

31

32

3334

38

38

3 8 1

382

383

39

310

40

50

53

54

Page

3 2

32

37

3 7

38

3 11

3 12

3 13

3 13

3 15

3 16

4 1

51

5 3

5-4

1 Dated July 1993 and approved m December 1993

iR \TABLES\2340003 TA1

CAR3184

FIGUREPROPOSED DOWNGRADIENT MONITORING WELL INSTALLATION SCHEDULE

COLORADO AVENUE SUBSITE HASTINGS NEBRASKA

Task Name

Submit Revised DGMW Installation Work Plan

EPA Review and Approval

Site Access Agreements

Subcontractor Bid and Selection

Mobilization

Drill and Install Wells

Well Development

Sol Disposition Sampling

Receive Laboratory Results Associated with Soil Disposal

Disposal of Soil Cuttings

Well Sampling

Survey Wells

Recei e Labo atory Results

D ta Validation

Pr pare Report

Start Date

2/7/96

2/7/962/7/96

2/7/96

2/14/96

2/17/96

3/3/96

3/3/96

3/4/96

3/18/96

4/5/96

3/6/96

4/10/96

5/10/96

5/15/96

Duration

OdSOOd

SOOd

700d

300d

1400d

300d

1 OOd

1400d

30 OOd

SOOd

200d

30 OOd

SOOd

30 OOd

End Date

2/7/96

2/11/96

2/11/96

2/13/96

2/16/96

3/2/96

3/5/96

3/3/96

3/17/96

4/16/96

4/9/96

3/7/96

5/9/96

5/14/96

6/14/96

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