95th air base wing edwards air force base, california

95th Air Base Wing Edwards Air Force Base, California Environmental Restoration Program Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan Addendum North Base Operable Unit 5/10 FINAL

November 2008

DEPARTMENT OF THE AIR FORCE HEADQUARTERS 95TH AIR BASE WING (AFMC)

EDWARDS AIR FORCE BASE, CALIFORNIA

6 November 2008 MEMORANDUM FOR SEE DISTRIBUTION FROM: 95 ABW/EMR

5 E. Popson Avenue, Bldg 2650A Edwards AFB CA 93524-8060

SUBJECT: Final Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work

Plan Addendum, North Base, Operable Unit 5/10 1. Transmitted herein are one hard copy and one electronic copy of the final document entitled: Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan Addendum, North Base, Operable Unit 5/10. This work plan addendum describes our Phase 2 treatability study to further evaluate the effectiveness of enhanced in situ bioremediation technology for treatment of chlorinated solvents and perchlorate in groundwater at Site 282. Expected start date for fieldwork is January 2009 with the study lasting 9-12 months. Three areas within the plume will be the areas of interest under this second phase. The Executive Summary, ES-1 and Section 2.3 provides further information on project scope and schedule. 2. If you have any questions or comments, please call me at (661) 277-1474.

AI DUONG Chief, Environmental Restoration Division

Attachment: Final Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan Addendum, North Base, Operable Unit 5/10 (hard copy and CD) DISTRIBUTION: Mr. Joseph Healy, U.S. EPA, Region 9 Mr. Kevin Depies, California DTSC Office of Military Facilities Mr. Jehiel Cass, California RWQCB, Lahontan Region Ms. Karla Brasaemle, TechLaw, Inc.

L:\WORK\102177\WP\03.01\282TEXT.DOC Site 282 Treatability Study Work Plan Addendum Final, November 2008

iii

TABLE OF CONTENTS

Section Title Page

EXECUTIVE SUMMARY ....................................................................................... ES-1

1.0 INTRODUCTION .......................................................................................... 1-11.1 PROJECT BACKGROUND .................................................................... 1-11.2 PROJECT PURPOSE AND SCOPE .......................................................... 1-2

2.0 TREATABILITY STUDY OBJECTIVES, ORGANIZATION, AND SCHEDULE ........... 2-12.1 TREATABILITY STUDY OBJECTIVES.................................................... 2-12.2 PROJECT ORGANIZATION .................................................................. 2-12.3 PROJECT SCHEDULE ......................................................................... 2-1

3.0 TREATABILITY STUDY DESIGN .................................................................... 3-13.1 TREATABILITY STUDY LOCATION AND DESCRIPTION.......................... 3-13.2 TRACER TEST ................................................................................... 3-13.3 SUBSTRATE DELIVERY ...................................................................... 3-73.4 BIOAUGMENTATION ........................................................................3-113.5 SAMPLING ANALYSES DURING TREATABILITY STUDY........................3-12

4.0 TREATABILITY STUDY IMPLEMENTATION .................................................... 4-14.1 WELL CONSTRUCTION AND DEVELOPMENT ....................................... 4-1

4.1.1 Reconnaissance/Permitting ............................................................ 4-14.1.2 Utility Clearance ........................................................................ 4-14.1.3 Drilling.................................................................................... 4-14.1.4 Well Installation ......................................................................... 4-24.1.5 Well Development ...................................................................... 4-44.1.6 Project-Derived Waste.................................................................. 4-44.1.7 Decontamination......................................................................... 4-44.1.8 Surveying ................................................................................. 4-5

4.2 TRACER TEST ................................................................................... 4-54.3 SODIUM LACTATE INJECTION AND MONITORING ................................ 4-64.4 BIOAUGMENTATION ......................................................................... 4-64.5 PERFORMANCE MONITORING ............................................................ 4-7

5.0 ANALYTICAL PROTOCOLS........................................................................... 5-15.1 ANALYTICAL DATA QUALITY LEVELS................................................ 5-1

6.0 DATA INTERPRETATION AND REPORTING .................................................... 6-16.1 DATA INTERPRETATION .................................................................... 6-16.2 REPORTING ...................................................................................... 6-1


iv

TABLE OF CONTENTS (Continued)

Section Title Page

7.0 PROJECT DOCUMENTS ................................................................................ 7-17.1 QUALITY ASSURANCE PROJECT PLAN ................................................ 7-17.2 FIELD SAMPLING PLAN ..................................................................... 7-17.3 HEALTH AND SAFETY PLAN .............................................................. 7-1

8.0 REFERENCES.............................................................................................. 8-1

LIST OF APPENDICES

APPENDIX A EARTH TECH FORMS APPENDIX B LOW FLOW/MINIMAL DRAWDOWN SAMPLING METHODS APPENDIX C HEALTH AND SAFETY PLAN APPENDIX D RESPONSES TO REGULATORY AGENCY COMMENTS


v

TABLE OF CONTENTS (Continued)

LIST OF FIGURES

Figure Title Page

1-1 Site 282 Treatability Study Treatment Area Locations ............................................... 1-33-1 Treatment Area 1 Proposed Well Locations............................................................ 3-23-2 Treatment Area 2 Proposed Well Locations............................................................ 3-33-3 Treatment Area 3 Proposed Well Locations............................................................ 3-43-4 Injected Tracer Volume Versus Dose Response Well Concentration.

Modified from Payne et al., 2008........................................................................ 3-63-5 Conceptual Diagram of the Site 282 Substrate Delivery System...................................3-10

LIST OF TABLES

Table Title Page

2-1 Key Personnel ............................................................................................... 2-22-2 Site 282 Treatability Study Schedule .................................................................... 2-33-1 Potential Injection Volumes for the Site 282 ISB Treatability Study (in Gallons)................ 3-94-1 Existing and Proposed Well and Borehole Specifications ............................................ 4-34-2 Performance Monitoring Schedule ....................................................................... 4-8


vi

LIST OF ABBREVIATIONS AND ACRONYMS

O degree µg/L micrograms per liter 95 ABW/CE 95th Air Base Wing, Civil Engineering 95 ABW/CEV 95th Air Base Wing, Environmental Management Division 95 ABW/EM 95th Air Base Wing, Environmental Management Directorate 95 ABW/EMR 95th Air Base Wing, Environmental Restoration Division AF Air Force AFB Air Force Base AFCEE Air Force Center for Engineering and the Environment (formerly known as

Air Force Center for Environmental Excellence) AFCEE/EXE Air Force Center for Engineering and the Environment, Execution Branch for

Restoration Program AFCEE/EXEW Air Force Center for Engineering and the Environment, Environmental

Programs Execution – West AFCEE/ISM Air Force Center for Environmental Excellence, Installation Support, Air Force Materiel Command AFFTC IMT Air Force Flight Test Center Industrial Management Tool AG amber glass ARAR applicable or relevant and appropriate requirement C Celsius COD chemical oxygen demand CT carbon tetrachloride DHC Dehalococcoides, spp. DO dissolved oxygen Earth Tech Earth Tech, Inc. EC electrical conductivity EPA Environmental Protection Agency ERP Environmental Restoration Program FSP field sampling plan gpm gallons per minute H2SO4 sulfuric acid HASP health and safety plan HCl hydrochloric acid HNO3 nitric acid HSA hollow-stem auger ISB in situ bioremediation ISE ion-specific electrode ITRC Interstate Technology Regulatory Council MCL maximum contaminant level mg/L milligrams per liter mL milliliter mL/L milliliters per liter MSDS Material Safety Data Sheet


vii

LIST OF ABBREVIATIONS AND ACRONYMS (Continued)

mV millivolts NA not applicable NTU nephelometric turbidity unit OD outside diameter ORP oxidation-reduction potential OU operable unit P plastic pH negative log of the hydrogen concentration PID photoionization detector PPE personal protective equipment PVC polyvinyl chloride QAPP quality assurance project plan QA/QC quality assurance/quality control qPCR quantitative polymerase chain reaction ROI radius of injection TCE trichloroethene TSWP treatability study work plan U.S. United States USAF United States Air Force VFA volatile fatty acid VOA volatile organic analysis VOC volatile organic compound


ES-1

EXECUTIVE SUMMARY

The United States Air Force is proposing a treatability study under the Environmental

Restoration Program to further evaluate the effectiveness of enhanced in situ bioremediation

(ISB) technology for treatment of solvent and perchlorate contaminated groundwater at Site 282,

North Base, Operable Unit 5/10, Edwards Air Force Base, California. A previous ISB

treatability study performed at the site from 2005 to 2007 was successful in reducing

contaminant concentrations; however, implementation was challenging due to operational difficulties

associated with the recirculation system. This ISB treatability study will evaluate direct injection of

sodium lactate into the aquifer via injection wells and transport under natural gradient conditions

(without recirculation) to promote biodegradation of site contaminants. Knowledge gained from the

treatability study will help to evaluate the feasibility, design, and implementation of a larger scale

application, if such an application is warranted, and to assess the potential to use this technology at

other locations on Base.

The Site 282 ISB treatability study will involve well installation, substrate (sodium lactate)

injection, and performance monitoring within three separate treatment areas associated with

high concentrations of chlorinated solvents or perchlorate relative to other areas of the site. A

tracer test will be performed to optimize substrate injection volumes. Bioaugmentation will

be performed in treatment areas with chlorinated solvent contamination. Additional substrate

injections will be performed based on performance monitoring results of previous injections.

Substrate injection, bioaugmentation, and performance monitoring will take place over approximately

12 months.

The treatability study will include a monitoring program that will provide data to measure radius of

injection, substrate longevity, redox conditions, and contaminant degradation. The treatability study

monitoring program will include sampling at various locations, measuring field parameters, and

collecting and analyzing samples for laboratory chemical analyses.


ES-2

A treatability study report will summarize the treatability study project methods and results. The report

will include:

Site description Description of field activities Contaminant concentration decline curves and calculations Performance comparison of recirculation and direct injection/natural gradient substrate delivery

methods Recommendations for cost and operational data for optimization of a larger scale application, if

warranted


1-1

1.0 INTRODUCTION

The United States Air Force (USAF) will perform an enhanced anaerobic in situ bioremediation (ISB)

treatability study to remediate chlorinated solvents and perchlorate at Site 282, Edwards Air Force Base

(AFB), California. ISB is considered to be an economical and technically feasible technology to

implement at Site 282 for the anticipated remediation goal and has the potential to meet applicable or

relevant and appropriate requirements (ARARs) in a relatively short time-frame. A previous ISB

treatability study was performed at the site from 2005 to 2007 in accordance with the Site 282

Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan (TSWP) (Earth Tech, 2005)

(Site 282 Enhanced Anaerobic ISB TSWP). This TSWP Addendum details additional ISB activities to

be performed at the site and was prepared by Earth Tech, Inc. (Earth Tech), in accordance with the

Guidance for Contract Deliverables (Air Force Center for Engineering and the Environment [AFCEE],

2002) and Guide for Conducting Treatability Studies under CERCLA (United States Environmental

Protection Agency [U.S. EPA], 1992).

1.1 PROJECT BACKGROUND

This section provides a brief summary of the previous Site 282 ISB treatability study. A detailed

discussion of field activities and analytical results for the previous study is provided in the Site 282

Enhanced Anaerobic In Situ Bioremediation Treatability Study Report (Earth Tech, 2008b). A detailed

description of the ISB technology can be found in the Site 282 Enhanced Anaerobic ISB TSWP

(Earth Tech, 2005).

Site 282 is located approximately 1 mile northwest from the northern boundary of Rogers Dry Lake.

Site 282 groundwater flows to the east-northeast at a relatively flat gradient. The lithology at the site

consists of interbedded coarse alluvial deposited interfingered with playa and lacustrine deposits that

generally dip toward the dry lake bed. This alluvium extends to approximately 400 feet bgs and is

underlain by older alluvium mainly derived from weathered granitic rock over granitic bedrock. A

more comprehensive description of the geology and hydrogeology at Site 282 is provided in

Section 1.2.1 of the Site 282 Enhanced Anaerobic ISB TSWP (Earth Tech, 2005).


1-2

From April 2006 to March 2007, an ISB recirculation treatment cell was operated at Site 282

(Figure 1-1) to stimulate enhanced ISB of relatively high trichloroethene (TCE) concentrations

(410 µg/L) and detectable concentrations of carbon tetrachloride (CT) and perchlorate. Sodium lactate

was injected into a recirculation treatment cell created between injection well 189-MW14 and extraction

well 189-MW15. The treatment cell was bioaugmented with the KB-1® dechlorinating culture.

Operation and maintenance of the recirculation system was labor intensive, and the system was prone to

mechanical failures due to power outages and biofouling. Despite operational difficulties, performance

monitoring results showed that concentrations of TCE, CT, and perchlorate, as well as their

degradation products, significantly decreased with corresponding increased detections of ethene and

methane (final end products of TCE and CT degradation, respectively) in wells that were affected by

the treatment system (wells 189-MW14 through 189–MW16). Contaminant concentrations in well

189-MW01, located in the middle of the recirculation cell and screened slightly shallower than the other

wells, did not significantly decrease due to poor hydraulic communication with the injection well.

1.2 PROJECT PURPOSE AND SCOPE

Based on the operational difficulties associated with the recirculation system of the initial ISB

treatability study, this treatability study will evaluate direct injection of sodium lactate into injection

wells under natural gradient conditions (without recirculation) to promote biodegradation of site

contaminants. A successful treatability study was performed using a similar injection strategy at

Site 19, Edwards AFB (Mora et al., 2008). Three target treatment areas were selected based on

relatively high concentrations of TCE, CT, and/or perchlorate (Figure 1-1). Treatment Area 1 will

primarily address TCE contamination and is located near well 189-MW01, which was not effectively

treated during the previous ISB treatability study. Treatment Area 2, located near well 282-MW01,

will primarily address CT and TCE contamination in a source area of the main solvent groundwater

plume. Treatment Area 3, located near well 189-MW03, will primarily address perchlorate

contamination at the leading edge of the perchlorate groundwater plume.

The scope of the ISB treatability study includes:

Installation of three additional monitoring wells within each treatment area. Performance of one 1-week tracer test to determine injection volume.


1-4

Injection of sodium lactate solution into each treatment area. Additional injections of sodium lactate will be performed, as needed, using monitoring data from the previous injection to optimize treatment.

Introduction of a bioaugmentation culture into Treatment Areas 1 and 2 to ensure complete degradation of TCE to ethane.

Performance monitoring of all groundwater wells within each treatment area. Preparation of a report presenting the methods and results of the study along with conclusions

and recommendations. This treatment is anticipated to reduce the mass, volume, and concentration of contaminants in the

groundwater while providing cost and operational data for system optimization and for planning a larger

scale ISB treatment application, if necessary.


2-1

2.0 TREATABILITY STUDY OBJECTIVES, ORGANIZATION, AND SCHEDULE

2.1 TREATABILITY STUDY OBJECTIVES

The previous ISB treatability study at Site 282 successfully illustrated the feasibility of treating

site contaminants to concentrations below their respective maximum contaminant levels (MCLs)

using ISB. Therefore, the objectives of this treatability study, listed below, are related to assessing

the effectiveness of an alternate ISB injection strategy, direct injection under natural gradient

conditions.

Evaluate distribution and longevity of sodium lactate Identify optimal design criteria such as volume of electron donor required, injection flowrate,

injection frequency, and monitoring frequency Compare performance of direct injection/natural gradient and recirculation electron

donor delivery methods and determine which method would be more effective at the site

Assess the potential feasibility of larger scale ISB treatability studies for contaminated groundwater at Site 282 and other potential locations on base

2.2 PROJECT ORGANIZATION

This section presents key personnel involved with performance of this ISB treatability study

(Table 2-1). For a detailed description of project organization and the responsibilities of each position,

please refer to the Site 282 Enhanced Anaerobic ISB TSWP (Earth Tech, 2005).

2.3 PROJECT SCHEDULE

Table 2-2 outlines the anticipated schedule of field activities associated with performance of the Site 282

treatability study. The schedule includes approximate duration and timing of well installation, a tracer

test, baseline sampling, the first injection event, bioaugmentation, and performance monitoring

following the first injection at each treatment area. The timing of subsequent injection events at each

treatment area will be based on previous monitoring results and the goal of maintaining optimal

geochemical conditions for efficient ISB (refer to Section 3.0). Approximately two performance

monitoring events will follow each injection to evaluate treatment and the need for a


2-2

TABLE 2-1. KEY PERSONNEL

Title Name Affiliation Phone Number Edwards AFB Project Manager Bruce Oshita 95 ABW/EMR 661-277-1439 AFCEE Project Manager William Hall AFCEE/EXEW 210-536-4412 Operable Unit 5/10 Project Manager Robert Kohlhardt Earth Tech 916-830-4365 Task Manager Rebecca Mora Earth Tech 562-951-2253 Field Task Leader Phil Saxton Earth Tech 661-810-0476 Project Quality Assurance Manager Chris Davis Earth Tech 408-232-2829 Project Health and Safety Professional Joe Bermudez Earth Tech 562-951-2242

Notes:

95 ABW/EMR = 95th Air Base Wing, Environmental Restoration Division AFB = Air Force Base AFCEE = Air Force Center for Engineering and the Environment AFCEE/EXEW = Air Force Center for Engineering and the Environment, Environmental Programs Execution - West Earth Tech = Earth Tech, Inc.


2-3

TABLE 2-2. SITE 282 TREATABILITY STUDY SCHEDULE

Task

Approximate Duration Approximate Dates

Well Installation & Development 1.5 months January through mid-February 2009

Tracer Test and Baseline Sampling 2 weeks 16-27 February 2009

Wait for Baseline Sampling Results and Evaluate Tracer Test Results

1 month Through March 2009

First Injection at Treatment Areas 1, 2, and 3 and Immediate Post-Injection Monitoring

3 weeks 6-24 April 2009

1-Month Post-Injection Sampling 1 week 26-29 May 2009

Bioaugmentation (Treatment Areas 1 and 2) 2 days 8-9 June 2009

2 to 4 Months Post-Injection Sampling 1 week July 2009

Additional Injections and Sampling (as needed) - Through March 2010


2-4

subsequent injection. It is anticipated that all injection and monitoring events will be performed within

a 12-month period.


3-1

3.0 TREATABILITY STUDY DESIGN

3.1 TREATABILITY STUDY LOCATION AND DESCRIPTION

The treatability study will be performed within three treatment areas located in the vicinities of existing

wells 189-MW01, 282-MW01, and 189-MW03 where high concentrations of site contaminants TCE

(150 µg/L), CT (79 µg/L), and/or perchlorate (42 µg/L) were detected during the most recent sampling

of these wells (Figure 1-1). In Treatment Area 1, existing well 189-MW01 will serve as the injection

well to ensure that contamination not treated during the previous ISB treatability study is treated.

Monitoring wells 189-MW20 through 189-MW22 will be installed in the vicinity of well 189-MW01

(Figure 3-1). In Treatment Area 2, a new injection well will be installed up gradient of existing well

282-MW01. When feasible, it is preferable to use existing wells as performance monitoring wells

instead of injection wells because they have historical data sets, making treatment trends easier to

evaluate. Injection well 282-MW03 and monitoring wells 282-MW04 and 282–MW05 will be installed

in the vicinity of existing well 282-MW01 (Figure 3-2). Similar to Treatment Area 2, in Treatment

Area 3 a new injection well, 189-MW23, and monitoring wells 189-MW24 and 189–MW25 will be

installed in the vicinity of existing well 189-MW03 (Figure 3-3). In general, each treatment area will

have one central injection well and surrounding monitoring wells located 7.5, 10, and 15 feet away

from the injection well. These well locations were selected to evaluate radial distribution of the injected

substrate and subsequent treatment.

3.2 TRACER TEST

In order to optimize the delivery of injected liquids (e.g., injection volume, ROI, and injection rate) and

well locations, a tracer test will be conducted within Treatment Area 1. The primary objective of the

tracer test is to calculate a mobile porosity for the site that can be used to determine the volume of

sodium lactate solution required to achieve a certain ROI. Typically, conductive aquifers having a total

porosity of 30 to 40 percent (similar to Site 282), have a mobile porosity value of 10 percent or less

(Payne et al., 2008). Mobile porosity represents the mobile pore space of the aquifer where injected

reagents are primarily transported.


3-5

The tracer test will be performed in Treatment Area 1 using wells 189-MW20 and 189–MW22.

Tracer-amended water will be injected into well 189-MW20 and the tracer concentration will be

monitored in well 189-MW22 (dose response well), located 7.5 feet away (Figure 3-1). The water

source for the tracer solution will be the Site 285 groundwater extraction and treatment system effluent

rather than potable water to avoid potential injection of trihalomethanes often generated during potable

water disinfection. The tracer solution with concentration Cinj will be injected at a constant rate

(estimated to be between 2 and 5 gallons per minute [gpm] based on previous observations at similar

Edwards AFB sites), and injection will continue until the tracer concentration in the dose response well

plateaus (Cmax), at which time, injection will cease and the total volume injected will be recorded. The

injection rate in the injection well, water levels in the injection well and surrounding wells, and the

tracer concentration in the dose response well will be monitored at least two to three times daily until

the maximum concentration is reached. The tracer concentration will also be monitored in additional

surrounding wells (189-MW01, 189-MW15, and 189–MW21) located 7.5 to 15 feet from

well 189-MW20, but less frequently.

Once the tracer test is complete, mobile porosity will be calculated based on the volume injected to reach

50 percent of the maximum observed concentration (Cmax/2) at the dose response well. A graph of tracer

concentration versus injected volume of tracer solution for the dose response well, similar to Figure 3-4,

will be generated and Equation 3-1 below will be used to calculate mobile porosity (Payne et al., 2008).

Equation 3-1

where:

θm = mobile porosity

Volinj 50 = volume of tracer injected when the observed concentration reached 50% of the maximum concentration

r = the distance of the injection well from the dose response well (7.5 feet)

h = screen length (10 feet)

hrVolinj

m ⋅⋅= 2

50

πθ


3-6

FIGURE 3-4. INJECTED TRACER VOLUME VERSUS DOSE RESPONSE WELL CONCENTRATION. MODIFIED FROM PAYNE ET AL., 2008.


3-7

Once calculated, the mobile porosity will be used to determine the required volume of substrate solution

to achieve a desired injection radius using Equation 3-2 (Payne et al., 2008):

Equation 3-2

Injection volumes are discussed further in Section 3.3.

3.3 SUBSTRATE DELIVERY

Food-grade sodium lactate was selected as the electron donor/substrate for this treatability study to

stimulate anaerobic biodegradation of TCE, CT, and perchlorate. This substrate was utilized during the

previous Site 282 ISB treatability study and successfully stimulated biodegradation of all three site

contaminants. Make-up water will be amended with sodium lactate and injected into the central

injection well of each treatment area (wells 189-MW01, 282-MW03, and 189-MW23). Extracted site

groundwater will serve as the make-up water for the initial injection at each area to avoid potential

injection of trihalomethanes, preserve site geochemical conditions, and limit contaminant displacement.

Groundwater will be extracted from the treatability study wells within each treatment area during well

development and stored in aboveground tanks dedicated to each treatment area.

Sodium lactate is typically sold as a 60 percent by weight solution, which is then diluted with water to

create a solution concentration of 3- to 30-percent sodium lactate by weight (Parsons, 2004) depending

on site conditions. Based on similar applications at other Edwards AFB sites (Earth Tech, 2008c), a

sodium lactate solution concentration of approximately 4 to 5 percent will be injected during the first

injection event in each treatment area to create reducing conditions favorable for contaminant

biodegradation. For treatment areas addressing TCE (Treatment Areas 1 and 2) these conditions

include dissolved oxygen (DO) < 0.5 milligrams per liter (mg/L), nitrate < 1 mg/L, sulfate

< 20 mg/L, methane 1 to 10 mg/L, oxidation reduction potential (ORP) < -100 millivolts (mV), and

pH between 5 and 9. For Treatment Area 3, these conditions include DO < 0.5 mg/L, nitrate

< 1 mg/L, and ORP between 0 and -100 mV. Because stronger reducing conditions are required in

Treatment Areas 1 and 2 due to the presence of TCE, a 5-percent sodium lactate solution will be

injected in those areas while a 4-percent sodium lactate solution will be injected in Treatment Area 3.

mhrVolume θπ ×××= 2


3-8

Based on results of the in situ bioremediation treatability study performed at Site 19, Edwards AFB,

which also had a slow groundwater velocity and flat hydraulic gradient, a large volume injection should

result in effective radial distribution from the injection well (Mora et al., 2008). Injection volumes

(total injection volume and volume of 60-percent sodium lactate) will be determined following

performance and evaluation of the tracer test. Table 3-1 summarizes potential injection volumes

required for the Site 282 treatability study depending on the mobile porosity value obtained from the

tracer test and a 10- or 15-foot ROI. The total injection volume will be selected based on achieving the

largest ROI while considering implementation logistics and contaminant displacement. The optimal

injection rate will be determined during the tracer test, but is expected to be between 2 and 5 gpm.

Ideally, each injection event within each treatment area will be completed within 5 working days

including mobilization/debmobilization.

The substrate delivery system used at each treatment area will include one or more polyethylene storage

tanks dedicated to each treatment area for make-up water, 60-percent sodium lactate stock solution, a

chemical metering pump, and a flow meter (Figure 3-5). A generator will be used as the power source

for the metering pump. Make-up water will be discharged from the polyethylene storage tank through

polyvinyl chloride (PVC) piping and pass through a flow meter. Sodium lactate will be added to the

injection line using the metering pump to create a 4- to 5-percent solution, which will then be injected

through flexible tubing lowered into the screen interval of each injection well. Valves within the

system will control the injection rate.

Immediately following sodium lactate injection at each treatment area, redox conditions and substrate

loading will be evaluated by measuring field parameters DO, ORP, and chemical oxygen demand

(COD) as well as collecting groundwater samples from all treatability study wells in each treatment area

and analyzing for volatile fatty acids (VFAs). Two additional sampling events, approximately 1 month

post-injection and 2 to 4 months post-injection, will be performed to evaluate substrate utilization,

redox conditions, and contaminant degradation. Sampling analyses are discussed in Section 3.5, and

the sampling schedule is discussed in Section 4.5. Sampling events for all three treatment areas will be

performed concurrently. If results from post-injection sampling events suggest that substrate is depleted

or optimal conditions for contaminant degradation are not being maintained in any of the treatment

areas, additional sodium lactate injections may be required. Injection volumes for subsequent injections

in each treatment area will be optimized based on performance monitoring results from the initial

TABLE 3-1. POTENTIAL INJECTION VOLUMES FOR THE SITE 282 ISB TREATABILITY STUDY(IN GALLONS)

0.02 0.04 0.06 0.08 0.10

Total Injection Volume (Water + Lactate)

470 940 1,410 1,880 2,350

60% Lactate Volume for 5% Solution 39 78 117 157 196


705 1,410 2,115 2,820 3,525



705 1,880 2,820 3,760 4,700



1,057 2,115 3,172 4,230 5,287



1,586 3,172 4,759 6,345 7,931



1,586 4,230 6,345 8,460 10,575


Notes:

% = percentft = feetROI = radius of injection

3-9

Treatment Area 1

Treatment Area 2

Treatment Area 3

15 ft ROI

10 ft ROI

Treatment Area 3

Mobile PorosityPotential Scenario

Treatment Area 1

Treatment Area 2

L:\WORK\102177\WP\03.01\TABLE3-1.XLS Site 282 Treatability Study Work Plan Addendum Final, November 2008


3-11

injection. If results from the 2- to 4-month sampling event show that optimal conditions for

contaminant biodegradation are being maintained, additional performance monitoring will be conducted

every 2 to 3 months until results indicate a subsequent injection is required.

To reduce the potential for biofouling, approximately 30 to 60 gallons of chase water will be injected

into each injection well at the end of each day during injection. The purpose of the chase water is to

push the sodium lactate solution out of the injection well and associated filter pack into the formation.

Groundwater levels will be monitored during injection to predict potential biofouling. If necessary,

injection wells experiencing biofouling will be physically cleaned via manual screen brushing and well

surge-block treatment.

3.4 BIOAUGMENTATION

Previous microcosm studies at Site 282 (Geosyntec, 2001) suggested that naturally-occurring

Dehalococcoides species (DHC), the only known isolate capable of complete reductive dechlorination

of tetrachloroethene and TCE to ethene, were sparse in the subsurface and bioaugmentation with a

microbial consortium containing DHC would reduce the chlorinated solvent concentration more quickly

and completely than with the use of electron donor alone. In addition, bioaugmentation with the

commercial microbial consortium KB-1® was performed during the previous Site 282 ISB treatability

study and was successful in enhancing reductive dechlorination of TCE. Based on these previous

studies, bioaugmentation with KB-1® will also be performed during this treatability study in

Treatment Areas 1 and 2 where TCE contamination exists. It is important to note that DHC is less

effective at sites with chlorinated solvent concentrations less than 100 micrograms per liter (µg/L), such

as Treatment Area 2. This is because DHC requires chlorinated solvents for growth. Bioaugmentation

has been performed at sites with TCE concentrations less than 100 µg/L; however, the KB-1® vendor

suggested additional culture (approximately three times that required for sites where TCE is greater

than 100 µg/L) be injected into Treatment Area 2 to avoid incomplete or a significant lag in efficient

dechlorination of TCE.

Prior to sodium lactate injection, a baseline microbial analysis will be conducted to evaluate the

presence of naturally-occurring DHC in the subsurface. Microbial analysis will also be conducted


3-12

during performance monitoring in order to confirm the presence and growth of DHC after

bioaugmentation.

The microbial consortium will be shipped to the site in a specially designed 22-liter vessel that will

exclude oxygen. Material Safety Data Sheets (MSDSs) will be made available by the manufacturer

prior to shipment. Prior to bioaugmentation in Treatment Areas 1 and 2, strongly anaerobic reducing

conditions (i.e., nitrate <1 mg/L, sulfate <20 mg/L, methane 1 to 10 mg/L, ORP < - 100 mV, DO

<0.5 mg/L) should be obtained in the aquifer to ensure the successful introduction and survival of

DHC in the subsurface. In addition, injection vessels and transfer lines will be purged with argon or

nitrogen gas to displace any oxygen before and during injection of the microbial consortium.

The microbial consortium will be directly injected from the vessel to the aquifer via injection

well 189-MW01 in Treatment Area 1 and injection well 282-MW03 in Treatment Area 2. The vessel

will be pressurized using argon or nitrogen to displace the culture to its final destination (below the

water table in the screened interval). Low pressures will be used and the pressure will be monitored

closely to mitigate potential damage to the injection wells. Bioaugmentation is expected to be

conducted after the 1-month post-injection sampling event, assuming strongly anaerobic conditions have

been achieved in each treatment area.

3.5 SAMPLING ANALYSES DURING TREATABILITY STUDY

Field and geochemical parameters as well as progress sampling analytes will be measured and used to

indicate changes within the subsurface environment. Microbial analysis will also be conducted. The

following details the sampling analyses to be conducted:

Field Parameters: o pH: The desired pH range for biological activity during reductive dechlorination is

between 5 and 9. Therefore pH will be monitored and a buffering agent may be added if the pH drops below 5.

o DO: Measurements can indicate whether the saturated zone conditions are chemically oxidizing (aerobic) or reducing (anaerobic).

o ORP: In the saturated zone, ORP indicates oxidizing or reducing conditions and provides an indication of which ion is the predominant electron acceptor.


3-13

o Specific Electrical Conductance: Because conductivity increases with the number of ions (electrically charged particles) in the water, it indicates the presence of dissolved substances such as cations, anions, or contaminants.

o Temperature: Affects the rates of microbial metabolism. Slower biodegradation occurs at lower temperatures.

o COD: COD concentrations will be monitored to evaluate substrate loading, distribution, and utilization.

Geochemical Parameters: o Nitrate: Nitrate is a competing electron acceptor for microbial respiration and

concentrations will be monitored to evaluate whether nitrate is being reduced in the aquifer. o Ferrous Iron: Elevated levels of ferrous iron indicate that iron-reducing conditions are

occurring in the aquifer and reductive dechlorination can occur. o Sulfate: Decreasing sulfate concentrations indicate that sulfate-reduction is occurring in the

aquifer and conditions are suitable for reductive dechlorination. o Sulfide: Elevated sulfide concentrations produced by sulfate reduction may inhibit

anaerobic dechlorination. o Dissolved Metals: Some metals may be more mobile under highly reducing conditions. o Chloride: Chloride is produced during reductive dechlorination. Concentrations several

times greater than background indicate dechlorination is occurring. o Alkalinity: During microbial respiration, carbon dioxide, carbonate, and bicarbonate are

produced. Therefore, if the alkalinity concentration is greater in the contaminant plume than in the background, this may be an indication of biological activity. In addition, alkalinity concentrations will be monitored in conjunction with pH to evaluate the buffering capacity of the aquifer during generation of acids from substrate fermentation.

o Total Organic Carbon (TOC): This parameter is used primarily to estimate dissolved organic matter and will be monitored to evaluate substrate loading, distribution, and utilization.

Progress Sampling Analytes: o Volatile Organic Compounds (VOCs)/daughter products: TCE, CT, and daughter

product concentrations will be monitored to evaluate whether biodegradation is occurring. o Perchlorate: Perchlorate concentrations will be monitored to evaluate whether

biodegradation of perchlorate is occurring. o Volatile Fatty Acids (VFAs including Acetate, Butyrate, Lactate, Propionate, and

Pyruvate): Provides a measure of the quantity of lactate and its transformation to other VFAs such as propionate and/or acetate.

o Dissolved Hydrocarbon Gases (Methane, Ethane, and Ethene): As ethene and ethane are the final biodegradation products of TCE, increases in their concentrations will be interpreted as evidence that biological degradation is occurring. Increases in methane concentrations in addition to strongly negative ORP readings will be interpreted as evidence that methanogenic conditions are being achieved in the aquifer.

Microbial Analysis: A real-time quantitative polymerase chain reaction (qPCR) method is used to monitor the DHC population in the subsurface.

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4.0 TREATABILITY STUDY IMPLEMENTATION

The sequence of operations of the treatability study implementation is summarized below in

chronological order:

Install and develop wells Perform tracer test Perform baseline groundwater sampling and analysis Perform substrate (sodium lactate) injection Perform groundwater performance monitoring Bioaugment Treatment Areas 1 and 2 with microbial consortium Perform additional groundwater performance monitoring Perform subsequent sodium lactate injections as needed and continue performance monitoring

4.1 WELL CONSTRUCTION AND DEVELOPMENT

4.1.1 RECONNAISSANCE/PERMITTING

Prior to the start of drilling, reconnaissance will be conducted to establish access routes and mark the

proposed drilling locations. A Base Work Clearance Request (Air Force [AF] Form 332) and digging

permit (Air Force Flight Test Center Industrial Management Tool [AFFTC IMT] Form 5926) will be

completed and submitted to 95th Air Base Wing Civil Engineering (95 ABW/CE) prior to drilling. The

appropriate Base personnel (e.g., Environmental Management, Communications, Base Operations,

Bioenvironmental) will be contacted as part of this effort. Well information will also be submitted to

the Kern County Environmental Health and Safety Department for each well that will be installed.

4.1.2 UTILITY CLEARANCE

A subsurface utility clearance survey will be performed at each drilling location, in accordance with the

Edwards Air Force Base Basewide Sampling and Analysis Plan, Volume II: Basewide Field Sampling

Plan (Basewide FSP) (Earth Tech, 2008a). The drilling locations will be cleared using conventional

geophysical techniques such as ground-penetrating radar, electromagnetic, and magnetometer surveys.

4.1.3 DRILLING

All drilling and well installation activities will be conducted under the supervision of a professional

geologist certified by the state of California. Soil samples will be collected from selected depth


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intervals for geological logging and a detailed log of the drilling activities and lithology will be

maintained by the site geologist. Drilling procedures are in accordance with the Basewide FSP

(Earth Tech, 2008a). Drill cuttings and open boreholes will be screened for VOCs throughout the

drilling procedures with a photoionization detector (PID) or organic vapor analyzer.

The hollow-stem auger (HSA) technique will be used to advance pilot boreholes. Eight-inch

outside-diameter (OD) continuous-flight HSAs in 5-foot sections will be advanced in the ground while

rotating. The pilot boreholes will be reamed using 10-inch OD augers that are sealed with a bottom

plug. After reaming, a well will be installed in each borehole. Further details regarding the HSA

drilling technique are provided in Section 4.1.4 of the Basewide FSP (Earth Tech, 2008a).

4.1.4 WELL INSTALLATION

Well installation procedures are described in Section 4.1.5 of the Basewide FSP (Earth Tech, 2008a).

Nine monitoring wells, 189-MW20 through 189–MW25 and 282-MW03 through 189–MW05, will be

installed in support of this treatability study. The proposed locations of these wells are shown on

Figures 3-1, 3-2, and 3-3 and the proposed well and borehole specifications are provided in Table 4-1.

Wells 189-MW20 through 189-MW22 will have 10-foot screen intervals while the remaining wells will

have 15-foot screen intervals. All well screens will have a slot size of 0.02 inches and will consist of

4-inch diameter, wire wrapped, schedule 5, type 304 stainless steel, with the exception of

wells 189-MW24 and 189–MW25, which will consist of 4-inch diameter slotted schedule 80 PVC.

Schedule 80 PVC blank casing will extend from the top of the screened interval to the ground surface if

the well is located on an existing road or sidewalk, or 2 feet above ground surface if the well is located

in an unpaved area to ensure visibility of the well. The filter pack will consist of Monterey #3 sand and

will be placed from the bottom of the well to approximately 2 feet above the well screen.

Approximately 1 foot of #30 transition sand will be placed above the filterpack. The actual slot size

and filter pack selection will be based on field-determined conditions. A bentonite seal will be placed

in a 3-foot interval above the sand pack and the remaining well annulus will be grouted to the surface

with a mixture composed of 95-percent Type II/V Portland cement and 5-percent bentonite.

TABLE 4-1. EXISTING AND PROPOSED WELL AND BOREHOLE SPECIFICATIONS

Well IdentificationTotal Depth

(feet bgs)

Static Water Level

(feet bgs)

Borehole Diameter (inches)

Well Diameter (inches)

SS Wirewrap Screen(feet)

PVC Casing (feet)

Treatment Area 1189-MW01 130 123 11 4 15 117(a)

189-MW20 133 - 10 4 10 123189-MW21 133 - 10 4 10 125(a)

189-MW22 133 - 10 4 10 123Treatment Area 2282-MW01 137 121 12 4 20 (b) 119(a)

282-MW03 137 - 10 4 15 122282-MW04 137 - 10 4 15 122282-MW05 137 - 10 4 15 124(a)

Treatment Area 3189-MW03 136 124 10 4 15 123(a)

189-MW23 136 - 10 4 15 123(a)

189-MW24 136 - 10 4 15(b) 123(a)

189-MW25 136 - 10 4 15(b) 123(a)

Notes:

Wells shown in bold are existing wells. (a) Additional footage included for above ground well completion with 2-foot stick-up. (b) Schedule 80 PVC slotted screen. bgs = below ground surface PVC = polyvinyl chloride SS = stainless steel - = no measurement

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4-4

4.1.5 WELL DEVELOPMENT

The groundwater wells will be developed no sooner than 24 hours and no later than 30 days after

installation. Development will be completed using a surge block in conjunction with either a bailer or

submersible pump. The temperature, pH, conductivity, and turbidity of the groundwater removed from

the well will be monitored throughout the development period. After the parameters stabilize

(e.g., temperature +1 degree Celsius [oC], pH +0.1 pH units, conductivity +5 percent of previous

readings, turbidity +10 nephelometric turbidity units [NTUs]), the water will be tested for settleable

solids. Well development is considered complete if the water is relatively free of sediment (turbidity

within +10 NTU, settleable solids less than 0.75 milliliters per liter [mL/L]). All data collected during

development will be recorded using a standard well development/purge log form (Appendix A).

Specific well development procedures are included in Section 4.1.5.3 of the Basewide FSP

(Earth Tech, 2008a).

4.1.6 PROJECT-DERIVED WASTE

Well construction and development generate project-derived waste, including soil cuttings and

groundwater. The waste will be containerized in 55-gallon Department of Transportation-approved

drums and polyethylene tanks. Wastes will be sampled to determine the appropriate method of

disposal. Following characterization, project-derived waste will be properly disposed.

Used personal protective equipment (PPE), such as coveralls, gloves, booties, and other refuse (e.g.,

plastic sheeting) will be decontaminated with a nonphosphate detergent and potable water, then placed

in plastic bags. These bags will be disposed either in an industrial dumpster or in a municipal landfill.

4.1.7 DECONTAMINATION

Decontamination of drilling equipment is required prior to mobilizing onsite as well as prior to moving

offsite following completion of site drilling activities. All downhole drilling tools, bits, drilling rods,

augers, and drill equipment will be decontaminated by the procedures documented in the Basewide FSP

(Earth Tech, 2008a).


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4.1.8 SURVEYING

Well locations will be determined utilizing a survey-grade global positioning system unit. Elevation

measurements will be made of the top of the inside well casing and of the ground surface adjacent to the

well. The measuring point will be clearly and permanently marked on the north side of the inside well

casing for future water level measurements. Casing elevations will be measured to the nearest

0.01 foot and ground surface elevations will be measured to the nearest 0.10 foot, referenced to mean

sea level. The horizontal location of the well will be measured to the nearest 0.10 foot and referenced

to the California State Plane Coordinates.

4.2 TRACER TEST

As discussed in Section 3.2, the tracer test will be performed in Treatment Area 1 primarily using

wells 189-MW20 and 189–MW22. Tracer solution will be injected into well 189-MW20 and the

groundwater tracer concentration will be monitored in well 189-MW22 located 7.5 feet away.

Bromide, a conservative tracer ion that is innocuous and resistant to physical and chemical interactions,

will be injected as the tracer. Bromide was previously used as a tracer at this site; therefore, prior to

tracer injection, baseline samples will be collected to establish background bromide concentrations.

While typical mobile porosity values for conductive aquifers range from 2 to 10 percent, it is important

to prepare enough tracer solution volume to reach the dose response well, 189-MW22, if the mobile

porosity is in the 15 to 20 percent range (Payne et al., 2008). Using Equation 3-2, the 10-foot screen

interval in well 189-MW20, an ROI of 7.5 feet, and a mobile porosity of 20 percent, the volume of

tracer solution prepared will be approximately 2,640 gallons. The tracer solution will be premixed at a

bromide concentration of 1,000 mg/L. The injection flow rate will be monitored during injection and

kept as constant as possible. The water level in the injection well and surrounding monitoring wells

will be recorded using pressure transducers set to record the water level at 10 minute intervals prior to,

during, and following injection until water levels return to static. Groundwater samples will be

collected from the dose response well and three additional surrounding monitoring wells and monitored

for bromide in the field using a bromide ion-specific electrode (ISE). Samples will be archived and

refrigerated until completion of the tracer test (estimated to be 5 days), at which time, a graph of field

monitoring data will be plotted to determine which samples will yield the most beneficial data. Selected


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samples will be shipped to an off-site laboratory for bromide analysis using EPA Method E300.0;

remaining samples will be sent to the laboratory on an as-needed basis to fill in any data gaps. The

laboratory hold time for bromide is 14 days; therefore, if the tracer test should continue for more than

1 week, samples may be shipped to the laboratory before completion of the injection.

4.3 SODIUM LACTATE INJECTION AND MONITORING

Upon completion of groundwater baseline characterization at each treatment area (Section 4.5), sodium

lactate injection will be performed. At each treatment area, injection make-up water will be transferred

from the polyethylene storage tank to the injection well via an injection line. A metering pump will

pump 60-percent sodium lactate stock solution from a 55-gallon drum through a feed line and into the

injection line where it will be mixed in-line with the make-up water to create a 4- to 5-percent sodium

lactate solution. The solution will then be injected into the screen interval of each injection well at the

optimal rate determined during the tracer test. Each injection will be performed for 8 to 10 hours a day

until the total injection volume is delivered.

During the injection, groundwater levels will be monitored daily to predict potential biofouling in the

subsurface. Immediately after the completion of each injection, groundwater samples will be collected

for field parameters (DO, ORP, specific conductivity, pH, and COD) as well as TOC and VFA

analyses to document initial substrate loading. Samples will be analyzed following published analytical

protocols (Earth Tech, 2008a).

4.4 BIOAUGMENTATION

Once the anaerobic redox conditions in the aquifer are obtained (most likely 1 month after sodium

lactate injection), bioaugmentation will be conducted in Treatment Areas 1 and 2 to stimulate faster and

more complete biodegradation. Approximately 3 liters of KB-1 ® will be injected into well 189-MW01

and approximately 9 liters of KB-1 ® will be injected into well 282-MW03 directly from the shipment

vessels. The vessels will be pressurized using argon or nitrogen to displace the culture to its final

destination (below the water table in the screened interval of each well).


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4.5 PERFORMANCE MONITORING

Performance monitoring will be conducted to evaluate and optimize treatment efficiency as well as

gather information for the design and operation of a long-term remediation system. Table 4-2

summarizes the proposed performance monitoring schedule including types of analyses and frequency

(baseline, immediately post-injection, 1 month post-injection and 2 to 4 months post-injection).

Groundwater samples will be collected from all treatability study wells in each treatment area during

each sampling event. In Treatment Area 1, field parameters will be collected from wells 189-MW14

through 189–MW17 after injection to evaluate whether they were affected by sodium lactate injection

(e.g., favorable conditions for reductive dechlorination of TCE exist) for additional ROI information.

Groundwater samples will not be collected from these wells, however, as contaminants were

successfully biodegraded during the previous treatability study. All groundwater sampling will be

performed using low-flow protocols (Appendix B) and the “Low Flow/Minimal Drawdown Well

Sampling Log” (form included in Appendix A). Personal hydrogen sulfide monitors will be worn

during groundwater sampling events until sulfate concentrations are reduced. Samples will be analyzed

following published analytical protocols (Earth Tech, 2008a).

If performance monitoring results suggest that sodium lactate is depleted or favorable conditions for

biodegradation cannot be sustained, additional rounds of sodium lactate injection may be warranted in

which case, a similar performance monitoring program will be implemented. The monitoring program

may change, however, depending on field conditions and the results of previous sampling events.

TABLE 4-2. PERFORMANCE MONITORING SCHEDULE

Analyte Analysis Type Method Sample Containers and Preservative Holding Time Frequency*Temperature Field Direct measure with YSI 600 XL or equivalent NA NA I,II,III,IVpH Field Direct measure with YSI 600 XL or equivalent NA NA I,II,III,IVEC Field Direct measure with YSI 600 XL or equivalent NA NA I,II,III,IVORP Field Direct measure with YSI 600 XL or equivalent NA NA I,II,III,IVFerrous Iron Field Hach Field Colorimeter - Method 8146 NA NA I,II,III,IVDO Field Hach Field Colorimeter - Method 8316 NA NA I,II,III,IVCOD Field Hach Field Colorimeter - Method 8000 NA NA I,II,III,IVVFAs Laboratory gas chromatagraph/flame ionization detector 1 40-mL VOA 14 days I,II,III,IVTOC Laboratory U.S. EPA Method 415.1 250 mL AG with H2SO4 (pH<2) 28 days I,III,IVVOCs Laboratory U.S. EPA Method 8260B 3 40-mL VOAs with HCl (pH<2) 14 days I,III,IVDissolved Gases Laboratory U.S. EPA Method RSKSOP 175 3 40-mL VOAs with HCl (pH<2) 14 days I,III,IVPerchlorate Laboratory U.S. EPA Method 314.0 1 250-mL P 28 days I,III,IVAlkalinity Laboratory U.S. EPA Method 2320B or 310.1 1 500-mL P 14 days I,III,IVAnions (sulfate, nitrate, chloride) Laboratory U.S. EPA Method 300.0 1 250-mL P 28 days I,III,IVSulfide Laboratory U.S. EPA Method 376.2 1 500-mL P 7 days I,III,IVDissolved Metals (field filtered) Laboratory U.S. EPA Method 6010B or 6020 1 500-mL P with HNO3 (pH<2) 6 months I,III,IV

Microbial (DHC) Laboratory qPCR 2 40-mL polys with glycerol 24 hoursPeriodic monitoring to determine distribution

and growth of DHC

Notes:

* Rounds II, III, and IV will be repeated after each injection. The length of time between rounds and the type of analyses included may be modified based on results of previous injections.AG = amber glass Sampling Round KeyCOD = chemical oxygen demand I - BaselineDHC = Dehalococcoides , spp. II - Immediately Post InjectionDO = dissolved oxygen III - 1 Month Post InjectionEC = specific electrical conductance IV - 2 to 4 Months Post InjectionH2SO4 = sulfuric acidHCl = hydrochloric acidHNO3 = nitric acidmL = milliliterNA = not applicableORP = oxidation-reduction potentialP = plasticpH = negative log of the hydrogen ion concentrationqPCR = quantitative polymerase chain reactionU.S. EPA = United States Environmental Protection AgencyVFA = volatile fatty acidVOA = volatile organic analysisVOC = volatile organic compound

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5-1

5.0 ANALYTICAL PROTOCOLS

Samples will be analyzed in accordance with the methods specified in the Edwards Air Force Base

Basewide Sampling and Analysis Plan, Volume I: Basewide Quality Assurance Project Plan

(Basewide QAPP) (Earth Tech, 2008a). Table 4-2 provides the recommended sample containers,

preservation, and holding times.

5.1 ANALYTICAL DATA QUALITY LEVELS

For a detailed description of analytical data quality levels, please refer to the Site 282 Enhanced ISB

TSWP (Earth Tech, 2005).

Except in the case of specialty analyses (e.g., qPCR and VFAs), analytical laboratory data generated

for this treatability study are required to be definitive-level data, which provide low detection limits, a

wide range of calibrated analytes, matrix recovery information, laboratory process control information,

and known precision and accuracy. Additional analytical and data reporting requirements for definitive

data are specified in the Basewide QAPP (Earth Tech, 2008a).


6-1

6.0 DATA INTERPRETATION AND REPORTING

6.1 DATA INTERPRETATION

Data obtained during the 12-month treatability study will be utilized real time to make decisions

regarding treatment optimization. Treatability study data will also be tabulated, reviewed, and

interpreted to estimate the rate and extent of enhanced anaerobic ISB of chlorinated solvents and

perchlorate. To the extent possible, factors affecting bioremediation performance and efficiency will be

identified.

6.2 REPORTING

Findings from the treatability study will be documented in a treatability study report. The report will

include data presentation as tables, figures, and calculations, summarized and presented in various

forms. The report will include methods, results, and discussion to assist in the decision-making process

for future remediation activities. Recommendations regarding the technical feasibility of larger scale

implementation of ISB at Site 282 using a natural gradient approach compared to the recirculation

approach used during the previous treatability study will be presented. The report will contain the

following information:

ISB study activities description Borehole and well completion logs Instrument readings and other field data Analytical results Contaminant concentration decline curves and calculations Injection data Interpretation of results Quality assurance/quality control (QA/QC) documentation including data validation criteria Conclusions and recommendations


7-1

7.0 PROJECT DOCUMENTS

This section presents the documents that provide direction for field crews or office staff in order to

meet the requirements of this study. These documents include the QAPP, the FSP, and the Health and

Safety Plan (HASP).

7.1 QUALITY ASSURANCE PROJECT PLAN

The Site 282 enhanced anaerobic ISB treatability study will be conducted in accordance with the

Basewide QAPP (Earth Tech, 2008a). Any deviation from the Basewide QAPP must be approved by

the project quality assurance manager and be documented in the project quality assurance summary

report that will be appended to the treatability study report.

7.2 FIELD SAMPLING PLAN

Project sampling procedures will be performed in accordance with the Basewide FSP (Earth Tech,

2008a). If field conditions necessitate deviation from the Basewide FSP prescribed procedures, the

field task leader will immediately contact the Earth Tech OU manager. All deviations will be

documented in the field and detailed in the treatability study report.

7.3 HEALTH AND SAFETY PLAN

Health and safety requirements will be followed in accordance with the updated Site 282 Treatability

Study HASP, which is provided in Appendix C of this work plan. Level D or modified Level D PPE is

assumed to be adequate for all of the field activities. However, PPE will be upgraded, if needed, based

upon field monitoring.


8-1

8.0 REFERENCES

Air Force Center for Environmental Excellence (AFCEE), 2002. Guidance for Contract Deliverables.

Earth Tech, Inc. (Earth Tech) 2005. Environmental Restoration Program, Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan, Final. Prepared for 95th Air Base Wing, Environmental Management Division (95 ABW/CEV), Edwards AFB, CA; Air Force Center for Environmental Excellence, Installation Support, Air Force Materiel Command (AFCEE/ISM), Brooks City-Base, TX. San Jose, CA. July.

⎯⎯—2008a. Environmental Restoration Program, Edwards Air Force Base Basewide Sampling and Analysis Plan, Volume I: Basewide Quality Assurance Project Plan and Volume II: Basewide Field Sampling Plan, Edwards Air Force Base, California, Final. Prepared for 95th Air Base Wing, Environmental Restoration Division (95 ABW/EMR), Edwards AFB, CA, and the U.S. Army Corps of Engineers (USACE), Sacramento District, Sacramento, CA. Long Beach, CA. February.

⎯⎯—2008b. Environmental Restoration Program, Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Report, North Base, Operable Unit 5/10, Final. Prepared for 95th Air Base Wing, Environmental Management Directorate (95 ABW/EM), Edwards AFB, CA, and Air Force Center for Engineering and the Environment, Execution Branch for Restoration Program (AFCEE/EXE), Brooks City-Base, TX. Sacramento, CA. February.

⎯⎯—2008c. Environmental Restoration Program, Site 301 Enhanced Anaerobic In Situ Bioremediation Treatability Study Report, Northwest Main Base, Operable Unit 8, Preliminary Draft. Prepared for 95 ABW/EM, Edwards AFB, CA, and the USACE, Sacramento District, Sacramento, CA. San Jose, CA. June.

Geosyntec Consultants, 2001. Laboratory Evaluation of Enhanced Bioremediation of Chlorinated Solvents in Groundwater, Operable Unit 5, Edwards Air Force Base, California. Prepared for Earth Tech, Inc. August.

Mora, Rebecca, Tamzen W. MacBeth, Tara MacHarg, Jagadish Gundarlahalli, Holly Holbrook, and Paul Schiff. 2008. “Enhanced Bioremediation Using Whey Powder for a Trichloroethene Plume in a High-Sulfate, Fractured Granitic Aquifer,” Remediation. Hoboken, New Jersey, Wiley Interscience. Summer 2008/Volume 18, Number 3.

Parsons Corporation, 2004. Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents. Prepared for the Air Force Center for Environmental Excellence, Brooks City-Base, Texas, Naval Facilities Engineering Service Center, Port Hueneme, California, and the Environmental Security Technology Certification Program, Arlington, Virginia. August.

Payne, F.C., J.A. Quinnan, and S.T. Potter. 2008. Remediation Hydraulics. Boca Raton, Florida, CRC Press.


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U.S. Environmental Protection Agency (U.S. EPA), 1992. Guide for Conducting Treatability Studies under CERCLA (Final), EPA/540/R-92/071a, October.

APPENDIX B

LOW FLOW/MINIMAL DRAWDOWN SAMPLING METHODS

1

STANDARD OPERATING PROCEDURE FOR

LOW-STRESS (LOW FLOW) / MINIMAL DRAWDOWN

GROUND-WATER SAMPLE COLLECTION

INTRODUCTION

The collection of “representative” water samples from wells is neither straightforward nor easily accomplished. Groundwater sample collection can be a source of variability through differences in sample personnel and their individual sampling procedures, the equipment used, and ambient temporal variability in subsurface and environmental conditions. Many site inspections and remedial investigations require the sampling at groundwater monitoring wells within a defined criterion of data confidence or data quality, which necessitates that the personnel collecting the samples are trained and aware of proper sample collection procedures.

The purpose of this standard operating procedure (SOP) is to provide a method that minimizes the amount of impact the purging process has on the groundwater chemistry during sample collection and to minimize the volume of water that is being purged and disposed. This will take place by placing the pump intake within the screen interval and by keeping the drawdown at a minimal level (0.33 feet) (Puls and Barcelona, 1996) until the water quality parameters have stabilized and sample collection is complete. The flow rate at which the pump will be operating will be depended upon both hydraulic conductivity of the aquifer and the drawdown with the goal of minimizing the drawdown. The flow rate from the pump during purging and sampling will be at a rate that will not compromise the integrity of the analyte that is being sampled. This sampling procedure may or may not provide a discrete ground water sample at the location of the pump intake. The flow of groundwater to the pump intake will be dependent on the distribution of the hydraulic conductivity (K) of the aquifer within the screen interval. In order to minimize the drawdown in the monitoring well a low-flow rate must be utilized. Low-flow refers to the velocity with which water enters the pump intake from the surrounding formation in the immediate vicinity of the well screen. It does not necessarily refer to the flow rate of water discharged at the surface, which can be affected by flow regulators or restrictions (Puls and Barcelona, 1996). This SOP was developed by the Superfund/RCRA Ground Water Forum and draws from U.S. EPA’s Ground Water Issue Paper, Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedure, by Robert W. Puls and Michael J. Barcelona. Also, available U.S. EPA Regional SOPs regarding Low-Stress (Low Flow) Purging and Sampling were used for this SOP.

SCOPE AND APPLICATION

This SOP should be used primarily at monitoring wells that have a screen or an open interval with a length of 10 feet or less and can accept a sampling device that minimizes the disturbance to the aquifer or the water column in the well casing. The screen or open interval should have been optimally located to intercept an existing contaminant plume(s) or along flowpaths of potential contaminant releases. Knowledge of the contaminant distribution within the screen interval is highly recommended and is essential for the success of this sampling procedure. The groundwater samples that are collected using this procedure are acceptable for the analyses of groundwater contaminants that may be found at Superfund and RCRA contamination sites. The analytes may be volatile, semivolatile organic

2

compounds, pesticides, PCBs, metals and other inorganic compounds. The screened interval should be located within the contaminant plume(s) and the pump intake should be placed at or near the known source of the contamination within the screened interval. It is critical to place the pump intake in the exact location or depth for each sampling event. This argues for the use of dedicated, permanently installed sampling devices whenever possible. If this is not possible, then the placement of the pump intake should be positioned with a calibrated sampling pump hose sounded with a weighted-tape or using a pre-measured hose. The pump intake should not be placed near the bottom of the screened interval to avoid disturbing any sediment that may have settled at the bottom of the well.

Water-quality indicator parameters and water levels must be measured during purging, prior to sample collection. Stabilization of the water quality parameters as well as monitoring water levels are a prerequisite to sample collection. The water-quality indicator parameters that are recommended include the following: specific electrical conductance, dissolved oxygen, turbidity, oxidation-reduction potential, pH, and temperature. The latter two parameters are useful data, but are generally insensitive as purging parameters. Oxidation-reduction potential may not always be appropriate stabilization parameter, and will depend on site-specific conditions. However, readings should be recorded because of its value as a double check for oxidation conditions, and for fate and transport issues. Also, when samples are collected for metals, semi-volatile organic compounds, and pesticides every effort must be made to reduce turbidity to 10 NTUs or less (not just the stabilization of turbidity) prior to the collection of the water sample. In addition to the measurement of the above parameters, depth to water must be measured during purging (U.S. Environmental Protection Agency, 1995).

Proper well construction, development and maintenance are essential for any ground-water sampling procedure. Prior to conducting the field work, information on the construction of the well and well development should be obtained and that information factored into the site specific sampling procedure. The attached Sampling Checklist is an example of the type of information that is useful.

Stabilization of the water-quality indicator parameters is the criterion for sample collection. But if stabilization is not occurring and the procedure has been strictly followed, then sample collection can take place once three (minimum) to six (maximum) casing volumes have been removed (Schuller et al., 1981 and U.S. Environmental Protection Agency, 1986; Wilde et al., 1998; Gibs and Imbrigiotta, 1990). The specific information on what took place during purging must be recorded in the field notebook or in the ground-water sampling log.

This SOP is not to be used where non-aqueous phase liquids (immiscible fluids) are present in the monitoring well.

3

EQUIPMENT

• Depth-to-water measuring device - An electronic water-level indicator or steel tape and chalk, with marked intervals of 0.01 foot. Interface probe for determination of liquid products (NAPL) presence, if needed.

• Steel tape and weight - Used for measuring total depth of well. Lead weight should not be used.

• Sampling pump - Submersible or bladder pumps with adjustable rate controls are preferred. Pumps are to be constructed of inert materials, such as stainless steel and Teflon®. Pump types that are acceptable include gear and helical driven, centrifugal (low-flow type) and air-activated piston. Adjustable rate, peristaltic pump can be used when the depth to water is 20 feet or less.

• Tubing - Teflon® or Teflon®-lined polyethylene tubing is preferred when sampling for organic compounds. Polyethylene tubing can be used when sampling inorganics.

• Power Source - If a combustion type (gasoline or diesel-driven) generator is used, it must be placed downwind of the sampling area.

• Flow measurement supplies - flow meter, graduated cylinder and a stop watch. • Multi-Parameter meter with flow-through-cell - This can be one instrument or more contained

in a flow-through cell. The water-quality indicator parameters that must be monitored are pH, ORP/EH, dissolved oxygen (DO), turbidity, specific conductance, and temperature. Turbidity readings must be collected before the flow cell because of the potential for sediment buildup that can bias the turbidity measurements. Calibration fluids for all instruments should be NIST-traceable and there should be enough for daily calibration throughout the sampling event. The inlet of the flow cell must be located near the bottom of the flow cell and the outlet near the top. The size of the flow cell should be kept to a minimum and a closed cell is preferred. The flow cell must not contain any air or gas bubbles when monitoring for the water-quality indicator parameters.

• Decontamination Supplies - Including a reliable and documented source of distilled water and any solvents (if used). Pressure sprayers, buckets or decontamination tubes for pumps, brushes and non-phosphate soap will also be needed.

• Sample bottles, sample preservation supplies, sample tags or labels and chain of custody forms. • Approved Field Sampling and Quality Assurance Project Plan. • Well construction data, field and water quality data from the previous sampling event. • Well keys and map of well locations. • Field notebook, ground-water sampling logs and calculator. A suggested field data sheet

(ground-water sampling record or ground-water sampling log) are provided in the attachment.

• Filtration equipment, if needed. An in-line disposable filter is recommended. • Polyethylene sheeting that will be placed on ground around the well head. • Personal protective equipment specified in the site Health and Safety Plan. • Air monitoring equipment as specified in the Site Health and Safety Plan. • Tool box - All needed tools for all site equipment used. • A 55-gallon drum or container to contain the purged water. Materials of construction of the sampling equipment (bladders, pumps, tubing, and other equipment that comes in contact with the sample) should be limited to stainless steel, Teflon®, glass and other inert material. This will reduce the chance of the sampling materials to alter the groundwater where concentrations of the site contaminants are expected to be near the detection limits. The sample tubing

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diameter thickness should be maximized and the tubing length should be minimized so that the loss of contaminants into and through the tubing walls may be reduced and the rate of stabilization of groundwater parameters is maximized. The tendency of organics to sorb into and out of material makes the appropriate selection of sample tubing material critical for trace analyses (Pohlmann and Alduino, 1992; Parker and Ranney, 1998).

PURGING AND SAMPLING PROCEDURES

The following describes the purging and sampling procedures for the Low-Stress (Low Flow)/ Minimal Drawdown method for the collection of ground-water samples. These procedures also describe steps for dedicated and non-dedicated systems.

Pre-Sampling Activities (Non-dedicated and dedicated system)

1. Sampling locations must begin at the monitoring well with the least contamination, generally upgradient or furthest from the site or suspected source. Then proceed systematically to the monitoring wells with the most contaminated ground water.

2. Check and record the condition of the monitoring well for damage or evidence of tampering. Lay out polyethylene sheeting around the well to minimize the likelihood of contamination of sampling/purging equipment from the soil. Place monitoring, purging and sampling equipment on the sheeting.

3. Unlock well head. Record location, time, date and appropriate information in a field logbook or on the ground-water sampling log (See attached ground-water sampling record and ground-water sampling log as examples).

4. Remove inner casing cap. 5. Monitor the headspace of the monitoring well at the rim of the casing for volatile organic

compounds (VOC) with a Photoionization detector (PID) or Flame ionization detector (FID), and record in the logbook. If the existing monitoring well has a history of positive readings of the headspace, then the sampling must be conducted in accordance with the Health and Safety Plan.

6. Measure the depth to water (water level must be measured to nearest 0.01 feet) relative to a reference measuring point on the well casing with an electronic water level indicator or steel tape and record in logbook or ground-water sampling log. If no reference point is found, measure relative to the top of the inner casing, then mark that reference point and note that location in the field logbook. Record information on depth to ground water in the field logbook or ground water sampling log. Measure the depth to water a second time to confirm initial measurement; measurement should agree within 0.01 feet or re-measure.

7. Check the available well information or field information for the total depth of the monitoring well. Use the information from the depth of water in step six and the total depth of the monitoring well to calculate the volume of the water in the monitoring well or the volume of one casing. Record information in field logbook or groundwater sampling log.

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Purging and Sampling Activities

8A. Non-dedicated system - Place the pump and support equipment at the wellhead and slowly lower the pump and tubing down into the monitoring well until the location of the pump intake is set at a pre-determined location within the screen interval. The placement of the pump intake should be positioned with a calibrated sampling pump hose, sounded with a weighted-tape, or using a pre-measured hose. Refer to the available monitoring well information to determine the depth and length of the screen interval. Measure the depth of the pump intake while lowering the pump into location. Record pump location in field logbook or groundwater sampling log.

8B. Dedicated system - Pump has already been installed, refer to the available monitoring well information and record the depth of the pump intake in the field logbook or ground-water sampling log.

9. Non-dedicated system and dedicated system - Measure the water level (water level must be measured to nearest 0.01 feet) and record information on the ground-water sampling log, leave water level indicator probe in the monitoring well.

10. Non-dedicated and dedicated system - Connect the discharge line from the pump to a flow-through cell. A “T” connection is needed prior to the flow cell to allow for the collection of water for the turbidity measurements. The discharge line from the flow-through cell must be directed to a container to contain the purge water during the purging and sampling of the monitoring well.

11. Non-dedicated and dedicated system - Start pumping the well at a low flow rate (0.2 to 0.5 liter per minute) and slowly increase the speed. Check water level. Maintain a steady flow rate while maintaining a drawdown of less than 0.33 feet (Puls and Barcelona, 1996). If drawdown is greater than 0.33 feet lower the flow rate. 0.33 feet is a goal to help guide with the flow rate adjustment. It should be noted that this goal may be difficult to achieve under some circumstances due to geologic heterogeneities within the screened interval, and may require adjustment based on site-specific conditions and personal experience (Puls and Barcelona, 1996).

12. Non-dedicated and dedicated system - Measure the discharge rate of the pump with a graduated cylinder and a stop watch. Also, measure the water level and record both flow rate and water level on the groundwater sampling log. Continue purging, monitor and record water level and pump rate every three to five minutes during purging. Pumping rates should be kept at minimal flow to ensure minimal drawdown in the monitoring well.

13. Non-dedicated and dedicated system - During the purging, a minimum of one tubing volume (including the volume of water in the pump and flow cell) must be purged prior to recording the water-quality indicator parameters. Then monitor and record the water-quality indicator parameters every three to five minutes. The water-quality indicator field parameters are turbidity, dissolved oxygen, specific electrical conductance, pH, redox-potential and temperature. Oxidation-reduction potential may not always be an appropriate stabilization parameter, and will depend on site-specific conditions. However, readings should be recorded because of its value as a double check for oxidizing conditions. Also, for the final dissolved oxygen measurement, if the readings are less than 1 milligram per liter, it should be collected and analyze with the spectrophotometric method (Wilde et al., 1998 Wilkin et al., 2001), colorimetric or Winkler titration (Wilkin et al., 2001). The stabilization criterion is based on three successive readings of the water quality field parameters; the following are the criteria which must be used:

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Parameter Stabilization Criteria Reference

pH ± 0.1 pH units Puls and Barcelona, 1996; Wilde et al.,

Specific electrical ± 3% S/cm Puls and Barcelona, 1996 conductance (SEC)

oxidation-reduction ± 10 millivolts Puls and Barcelona 1996 potential (ORP)

turbidity ± 10 % NTUs (when Puls and Barcelona, 1996 turbidity is greater than Wilde et al., 1998 10 NTUs)

dissolved oxygen ± 0.3 milligrams per liter Wilde et al., 1998

Once the criteria have been successfully met indicating that the water quality indicator parameters have stabilized, then sample collection can take place.

14. If a stabilized drawdown in the well can’t be maintained at 0.33 feet and the water level is approaching the top of the screened interval, reduce the flow rate or turn the pump off (for 15 minutes) and allow for recovery. It should be noted whether or not the pump has a check valve. A check valve is required if the pump is shut off. Under no circumstances should the well be pumped dry. Begin pumping at a lower flow rate, if the water draws-down to the top of the screened interval again turn pump off and allow for recovery. If two tubing volumes (including the volume of water in the pump and flow cell) have been removed during purging then sampling can proceed next time the pump is turned on. This information should be noted in the field notebook or groundwater sampling log with a recommendation for a different purging and sampling procedure.

15. Non-dedicated and dedicated system - Maintain the same pumping rate or reduce slightly for sampling (0.2 to 0.5 liter per minute) in order to minimize disturbance of the water column. Samples should be collected directly from the discharge port of the pump tubing prior to passing through the flow-through cell. Disconnect the pump’s tubing from the flow-through-cell so that the samples are collected from the pump’s discharge tubing. For samples collected for dissolved gases or Volatile Organic Compounds (VOCs) analyses, the pump’s tubing needs to be completely full of ground water to prevent the ground water from being aerated as the ground water flows through the tubing. The sequence of the samples is immaterial unless filtered (dissolved) samples are collected and they must be collected last (Puls and Barcelona, 1996). All sample containers should be filled with minimal turbulence by allowing the ground water to flow from the tubing gently down the inside of the container. When filling the VOC samples a meniscus must be formed over the mouth of the vial to eliminate the formation of air bubbles and head space prior to capping. In the event that the ground water is turbid,(greater then 10 NTUs), a filtered metal (dissolved) sample also should be collected.

If filtered metal sample is to be collected, then an in-line filter is fitted at the end of the discharge tubing and the sample is collected after the filter. The in-line filter must be pre-rinsed following manufacturer’s recommendations and if there are no recommendations for rinsing, a minimum of 0.5 to 1 liter of ground water from the monitoring well must pass through the filter prior to sampling.

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16A. Non-dedicated system - Remove the pump from the monitoring well. Decontaminate the pump and dispose of the tubing if it is non-dedicated.

16B. Dedicated system - Disconnect the tubing that extends from the plate at the wellhead (or cap) and discard after use.

17. Non-dedicated system - Before locking the monitoring well, measure and record the well depth (to 0.1 feet). Measure the total depth a second time to confirm initial measurement; measurement should agree within 0.01 feet or re-measure.

18. Non-dedicated and dedicated system - Close and lock the well. DECONTAMINATION PROCEDURES

Decontamination procedures for the water level meter and the water quality field parameter sensors. The electronic water level indicator probe/steel tape and the water-quality field parameter sensors will be decontaminated by the following procedures: 1. The water level meter will be hand washed with phosphate free detergent and a scrubber, then

thoroughly rinsed with distilled water. 2. Water quality field parameter sensors and flow-through cell will be rinsed with distilled water

between sampling locations. No other decontamination procedures are necessary or recommended for these probes since they are sensitive. After the sampling event, the flow cell and sensors must be cleaned and maintained per the manufacturer’s requirements.

Decontamination Procedure for the Sampling Pump

Upon completion of the ground water sample collection the sampling pump must be properly decontaminated between monitoring wells. The pump and discharge line including support cable and electrical wires which were in contact with the ground water in the well casing must be decontaminated by the following procedure:

1. The outside of the pump, tubing, support cable and electrical wires must be pressured sprayed with soapy water, tap water and distilled water. Spray outside of tubing and pump until water is flowing off of tubing after each rinse. Use bristle brush to help remove visible dirt and contaminants.

2. Place the sampling pump in a bucket or in a short PVC casing (4-in. diameter) with one end capped. The pump placed in this device must be completely submerged in the water. A small amount of phosphate free detergent must be added to the potable water (tap water).

3. Remove the pump from the bucket or 4-in. casing and scrub the outside of the pump housing and cable.

4. Place pump and discharge line back in the 4-in. casing or bucket, start pump and re-circulate this soapy water for 2 minutes (wash).

5. Re-direct discharge line to a 55-gallon drum, continue to add 5 gallons of potable water (tap water) or until soapy water is no longer visible.

6. Turn pump off and place pump into a second bucket or 4-in. Casing which contains tap water, continue to add 5-gallons of tap water (rinse).

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7. Turn pump off and place pump into a third bucket or 4-in. casing that contains distilled/deionized water, continue to add three to five gallons of distilled/deionized water (final rinse).

8. If a hydrophobic contaminant is present (such as separate phase, high levels of PCB’s, etc.) An additional decon step, or steps, may be added. For example, an organic solvent, such as reagent-grade isopropanol alcohol may be added as a first spraying/bucket prior to the soapy water rinse/bucket.

FIELD QUALITY CONTROL

Quality control (QC) samples must be collected to verify that sample collection and handling procedures were performed adequately and that they have not compromised the quality of the ground water samples. The appropriate EPA program guidance must be consulted in preparing the field QC sample requirements for the site-specific Quality Assurance Project Plan (QAPP).

There are five primary areas of concern for quality assurance (QA) in the collection of representative ground-water samples:

1. Obtaining a ground-water sample that is representative of the aquifer or zone of interest in the aquifer. Verification is based on the field log documenting that the field water-quality parameters stabilized during the purging of the well, prior to sample collection.

2. Ensuring that the purging and sampling devices are made of materials, and utilized in a manner, which will not interact with or alter the analyses.

3. Ensuring that results generated by these procedures are reproducible; therefore, the sampling scheme should incorporate co-located samples (duplicates).

4. Preventing cross-contamination. Sampling should proceed from least to most contaminated wells, if known. Field equipment blanks should be incorporated for all sampling and purging equipment, and decontamination of the equipment is therefore required.

5. Properly preserving, packaging, and shipping samples. All field quality control samples must be prepared the same as regular investigation samples with regard to sample volume, containers, and preservation. The chain of custody procedures for the QC samples will be identical to the field ground water samples. The following are quality control samples that must be collected during the sampling event:

Sample Type Frequency Field duplicates 1 per 10 samples Matrix spike 1 per 20 samples Matrix spike duplicate 1 per 20 samples Equipment blank 1 per day when reusable sampling equipment is used Trip blank (VOCs) 1 per sample cooler Temperature blank 1 per sample cooler

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HEALTH AND SAFETY CONSIDERATIONS

Depending on the site-specific contaminants, various protective programs must be implemented prior to sampling the first well. The site Health and Safety Plan should be reviewed with specific emphasis placed on the protection program planned for the sampling tasks. Standard safe operating practices should be followed, such as minimizing contact with potential contaminants in both the liquid and vapor phase through the use of appropriate personal protective equipment.

Depending on the type of contaminants expected or determined in previous sampling efforts, the following safe work practices will be employed:

Particulate or metals contaminants 1. Avoid skin contact with, and incidental ingestion of, purge water. 2. Use protective gloves and splash protection. Volatile organic contaminants 1. Avoid breathing constituents venting from well. 2. Pre-survey the well head space with an appropriate device as specified in the Site Health

and Safety Plan. 3. If monitoring results indicate elevated organic constituents, sampling activities may be

conducted in level C protection. At a minimum, skin protection will be afforded by disposable protective clothing, such as Tyvek®.

General, common practices should include avoiding skin contact with water from preserved sample bottles, as this water will have pH less than 2 or greater than 10. Also, when filling pre-acidified VOA bottles, hydrochloric acid fumes may be released and should not be inhaled.

POST-SAMPLING ACTIVITIES

Several activities need to be completed and documented once ground-water sampling has been completed. These activities include, but are not limited to:

1. Ensure that all field equipment has been decontaminated and returned to proper storage location. Once the individual field equipment has been decontaminated, tag it with date of cleaning, site name, and name of individual responsible.

2. All sample paperwork should be processed, including copies provided to the Regional Laboratory, Sample Management Office, or other appropriate sample handling and tracking facility.

3. All field data should be complied for site records. 4. All analytical data when processed by the analytical laboratory, should be verified against

field sheets to ensure all data has been returned to sampler.

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REFERENCES

Gibs, J. and T.E. Imbrigiotta, 1990, Well-Purging Criteria for Sampling Purgeable Organic Compounds; Ground Water, Vol. 28, No. 1, pp 68-78.

Pohlmann, K.F. and A.J. Alduino, 1992, Ground-Water Issue Paper: Potential Sources of Error in Ground-Water Sampling at Hazardous Waste Sites, EPA/540/S-92/019.

Puls, R.W. and M.J. Barcelona, 1996, Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedure, EPA/540/S-95/504, 12 pp.

Schuller, R.M., J.P. Gibb and R.A Griffin, 1981, Recommended Sampling Procedures for Monitoring Wells; Ground Water Monitoring Review, Spring 1981, pp. 42-46.

Parker, L.V. and T.A. Ranney, 1998, Sampling Trace-Level Organic Solutes with Polymeric Tubing: Part 2, Dynamic Studies; Ground Water Monitoring and Remediation, Vol. 18, No. 1, pp. 148-155.

U.S. Environmental Protection Agency, 1986, RCRA Ground-Water Monitoring Technical Enforcement Guidance Document; OSWER-9950.1, U.S. Government Printing Office, Washington, D.C., 208 pp., appendices.

U.S. Environmental Protection Agency, 1995, Ground Water Sampling - A Workshop Summary, Texas, November 30-December 2, 1993, EPA/600/R-94/205, 146 pp.

U.S. Environmental Protection Agency Region 1, 1996, Low Stress (low flow) Purging and Sampling Procedure For the collection of Ground water Samples From Monitoring Wells, SOP#: GW 0001, July 30, 1996.

U.S. Environmental Protection Agency Region 2, 1998, Ground Water Sampling Procedure Low Stress (Low Flow) Purging and Sampling, GW Sampling SOP Final, March 16, 1998.

Wilde, F.D., D.B. Radtke, J.Gibs and R.T. Iwatsubo, eds., 1998, National Field Manual for the Collection of Water-Quality Data; U.S. Geological Survey Techniques of Water-Resources Investigations, Book 9, Handbooks for Water-Resources Investigations, variously paginated.

Wilkin, R.T., M.S. McNeil, C.J. Adair and J.T. Wilson, 2001, Field Measurement of Dissolved Oxygen: A Comparison of Methods, Ground Water Monitoring and Remediation, Vol. 21, No. 4, pp. 124132.

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SAMPLING CHECKLIST

Well Identification:________________________

Map of Site Included: Y or N Wells Clearly Identified w/ Roads: Y or N Well Construction Diagram Attached: Y or N

Well Construction:

Diameter of Borehole:________ Diameter of Casing:__________ Casing Material:____________ Screen Material:______________ Screen Length:_____________ Total Depth:______________ Approximate Depth to Water:_____________ Maximum Well Development Pumping Rate:_________________ Date of Last Well Development:_____________ Previous Sampling Information:

Was the Well Sampled Previously: Y or N (If Sampled, Fill Out Table Below)

Table of Previous Sampling Information

Parameter Previously Sampled

Number of Times Sampled

Maximum Concentration

Notes (include previous purge rates)

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Groundwater Sampling Log

Site Name: Well #: Date:

Well Depth (Ft-BTOC1): Screen Interval (Ft):

Well Dia.: Casing Material: Sampling Device:

Pump placement(Ft from TOC2):

Measuring Point: Water level (static)(Ft):

Water level (pumping)(Ft): Pump rate(Liter/min):

Sampling Personnel:

Other info: (such as sample numbers, weather conditions and field notes)

Water Quality Indicator Parameters

Time Pumping rates (L/min)

Water level (ft)

DO (mg/l)

ORP (mv)

Turb. (NTU)

SEC3 (S/cm)

pH Temp. (Cº)

Volume pumped (L)

Type of Sample collected: 1-casing volume was: Total volume purged prior to sample collection: 1BTOC-Below Top of Casing 2TOC-Top of Casing 3Specific electrical conductance

Stabilization Criteria DO ± 0.3 mg/l Turb. ± 10% SEC ±3% ORP ± 10 mv pH ± 0.1 unit

PASSIVE SAMPLING (MINIMAL PURGE SAMPLING) Introduction Unlike water supply wells, wells installed for ground water quality assessment and restoration programs are often installed in low water yielding settings (e.g. clays, silts), or geologic or aquifer heterogeneities within the screened intervals (Puls and Barcelona, 1996). When purging a well, the primary consideration is to avoid well evacuation (dewatering of the well screen). Well dewatering can pose several problems (QED 2003): • Purging below top of screen can cause water entering the well to “cascade” inside the well

screen as the well recovers, resulting in a change in dissolved gasses and redox state and ultimately affecting the concentration of the analytes of interest through the oxidation of dissolved metals and possible loss of VOCs;

• Dewatering the screen drains water from the sand pack surrounding the screen, resulting in air being trapped in the pore spaces with lingering effects on dissolved gas levels and redox state;

• Where the well screen is submerged, drawdown below the top of screen could induce movement of vadose zone gases into the well, resulting in false-positive or biased analytical result for VOCs;

• Stress on the formation and stirring up of any settled solids in the bottom of the well can result in increased sample turbidity;

• The time required for sufficient recovery of the well may be excessive, affecting sample chemistry through prolonged exposure to the atmosphere. In some cases, the well may not recover sufficiently to produce the sample volume required within a reasonable time period.

Low flow/low volume sampling overcomes many of the limitations created by traditional well volume purging. By pumping at low flow rates when using low flow methodology, the disturbance to the water column in the well and stress on the surrounding formation is kept to a minimum. Hence, sample turbidity is less and sample chemistry alteration is minimized. The low flow approach purges water only from the screened zone. Therefore, the volume of water purged out of the well needed to achieve stable water conditions can be significantly reduced from the traditional approach (purging three to five volumes of water). This is especially ideal where wells are set in low hydraulic conductivity formations, possibly in wells set in fractured rock, or in general, where wells may not yield enough water sufficiently to achieve representative samples of the groundwater. For wells that cannot achieve a stabilized water level even at the very low pumping rates (< 0.1 L/min), alternative types of sampling such as passive or minimal pure sampling techniques are needed in these types of environments (Powell and Puls, 1997). Passive sampling generates the lowest purge volume of any technique and would essentially entail acquisitions of the sample with no or very little purging using dedicated sampling system installed within a screened interval or a passive sample collection device (Puls and Barcelona, 1997). When this method is used properly, it also has the potential for providing the best contaminant concentration data (Powell and Puls, 1997).

Application When using passive sampling system techniques, the volume should be minimized by using very small diameter tubing and the smallest possible pump chamber volume (QED, 2003). Plastic tubing should have sufficient wall thickness to minimize the potential for oxygen transfer through the tubing when pumping at very low flow rates (QED, 2003). After purging 1-3 volumes of the sampling system, the samples are then taken from the subsequent water being pumped. Since passive sampling requires the minimum possible disturbance to the water column and surrounding formation, dedicated sampling systems are required for this approach. Passive sampling collection requires insertion of the device into the screened interval for a sufficient time period to allow flow and sample equilibration before extraction for analysis (Powell and Puls, 1996). The pumping rates used for passive/minimal purge sampling are much lower than for low-flow/low-volume purging, generally 100 ml/minute or less. Drawdown is expected, since it cannot be avoided; however, it is still advisable to pump at the lowest possible rate to limit drawdown to the minimum possible. As with low-flow/low-volume techniques, the water level in the well should not be lowered below the top of the screen if possible. Monitoring indicator parameters for stability is not part of this approach, since the intention is not to purge until stabilization of these measurements. However, pumping through a flow cell is still the best way to get field measurements prior to sampling. Where the total volume of water in the well is very small, field measurements can be accomplished with a very small volume flow cell (< 50 ml), or grab sampling and measurements can be used. It may be necessary to work with the analytical laboratory to reduce the sample volumes to the minimum possible to reduce the total volume of water removed. This is also useful from a practical standpoint, since the time required to fill larger sample containers may be lengthy at the very low flow rates used. As suggested in Powell and Puls (1997), a typical passive-sampling scenario can be simple as: 1) Adjusting the pump/controller to the proper (slow) sampling speed and turning it off 2) 2)Attaching the pump/controller to the tubing exiting the well and starting the pump. 3) Purging enough water to remove the sampling device volume at least once (two to three

times might be preferable but the risk of acquiring stagnant casing water increases with each device volume removed).

4) Collecting and preserving the samples 5) Measuring the water level (Note: This step should always follow the sampling when using

passive techniques to avoid initial disturbance to the stagnant water). 6) Closing up and proceeding to the next well. References: Severn Trent- QED Environmental Systems (QED), 2003. Low-Flow/Low-Volume Purging and Sampling of Ground-Water Monitoring Wells Performance and Application Criteria Version 8, April 2003, 19 pp. Powell, R. M. and R.W. Puls, 1997, Hitting the Bull’s-Eye in Groundwater Sampling, Pollution Engineering International, Winter 1997, pp. 12-15.

Puls, R.W. and M.J. Barcelona, 1996, Low-Flow (Minimal Drawdown) Ground-water Sampling Procedure, EPA/540/S-95/504, 12 pp.

APPENDIX D

RESPONSES TO REGULATORY AGENCY COMMENTS

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Responses to Regulatory Agency Comments Draft Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan Addendum

North Base, Operable Unit 5/10, Edwards AFB, California, dated August 2008 Reviewer Comment # Comment Response

Joseph Healy (U.S. EPA) 1 EPA reviewed this document and has no comments. Comment noted. No action taken. Michael Finch (DTSC) General

Comment 1 The GSU questions if optimal site characterization has been performed at the Site to maximize in-situ bioremediation (ISB). The vertical extent of contamination does not appear to have been determined. Of particular note, crystalline rocks compose the Site’s basement. Three-D seismic imagery techniques may be useful to determine fracture bound ground water flow in crystalline rocks. Another site investigation approach to consider is a tight grid of passive soil gas samplers (such as Goresorbers) drilled into the shallow soil or rock. The results may reveal preferential pathways containing volatile organic compounds (VOCs). Recommendation: The GSU recommends further Site characterization especially in the vertical extent. Consider the use of 3-D seismic techniques and passive soil gas sampling.

The vertical extent of contamination was determined using a variety of techniques, including the installation of wells screened at deeper intervals (Wells 189-MW05 and 189-MW07 on Figure 1-1) and hydropunch sampling (Remedial Investigation [RI] Summary Report Operable Unit 5/10 [Earth Tech, 2008]). Bedrock is more than 300 feet below the targeted treatment interval (see Section 1.1, Paragraph 2). Therefore, 3-D imagery is not applicable. Identification of preferential pathways is not considered necessary for this treatability study given that the geology of the area is alluvium and the target treatment areas are relatively small.

Michael Finch (DTSC) General Comment 2

Due to the presence of unconsolidated sediments, the use of zero-valence iron may be suitable for VOC reduction at the Site. Recommendation: Consider the use of a zero-valence iron wall at the Site.

Nanoscale zero-valent iron (NZVI) was used previously at this site during another treatability study performed in 2005. The results of this study showed that although NZVI could reduce contaminant concentrations, NZVI mobility was extremely limited (less than 6 feet). For further details, refer to Section 4.11.3.5.1 of the OU5/10 RI Summary Report (Earth Tech, 2008). The proposed treatability study was designed to evaluate a targeted source area treatment approach, and therefore, a barrier application is not applicable for this study.

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Responses to Regulatory Agency Comments

Draft Site 282 Enhanced Anaerobic In Situ Bioremediation Treatability Study Work Plan Addendum North Base, Operable Unit 5/10, Edwards AFB, California, dated August 2008

Reviewer Comment # Comment Response Michael Finch (DTSC) General

Comment 3 The GSU notes that in the first phase of the ISB well 189-MW01 did not show significant breakdown of VOCs (note the possible exception in Detailed Comment number 11 below) despite its location between the injection and extraction points. All of the other wells exhibited significant VOC breakdown. This result suggests preferential pathways exclusive of 189-MW01. Recommendation: Consider conducting a preferential ground water pathway analysis.

Rather than being indicative of a preferential pathway, the lack of connectivity observed during the first phase of the treatability study is most likely due to the more shallow screen interval of Well 189-MW01, as shown in the attached figure from the Site 282 Bioremediation Treatability Study Report. The proposed new monitoring wells will be screened similarly to Well 189-MW01.

Michael Finch (DTSC) General Comment 4

The GSU notes that biobarrier contact time using groundwater flow velocities was not performed at the Site. Usually a contact time of at least 30 days is necessary to complete ISB. The GSU realizes that the groundwater gradient is low at this location, but flow gradients were measurable and should be used to achieve adequate contact time. Recommendation: Insure adequate ISB contact time using Site-specific ground water velocity data.

The treatment proposed in this work plan is hot spot treatment. Unlike a biobarrier, this treatment approach uses multiple applications of soluble electron donor to target one specific area, not to prevent migration of contaminants beyond a certain point. Groundwater velocities at the site are estimated to range between 11.51 and 34.97 feet per year (0.03 to 0.1 feet per day), as reported in the Site 282 Treatability Study Work Plan (Earth Tech, 2005), which means that the injected donor will not travel far beyond the initial injection radius before it is consumed. Contact time will not be an issue at these sites.

Michael Finch (DTSC) Detailed Comment 1

Page 1-2. The Report acknowledged that biofouling led to difficulties in the first phase of ISB. Have the biofouling organism(s) been identified? Recommendation: Consider well disinfection before bioaugmentation.

Well disinfection will not be used, since disinfection measures would cause problems with subsequent proposed bioaugmentation. During the first in situ bioremediation (ISB) treatability study at Site 282, biofouling was mainly a problem in the extraction well. Since groundwater extraction will not be used during these injections, biofouling is not anticipated to be a problem. The last paragraph in Section 3.3 of the Report describes the preventative measures as well as contingency plans should biofouling occur. The organisms that caused the biofouling in the first phase of the study were not identified.

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Reviewer Comment # Comment Response Michael Finch (DTSC) Detailed

Comment 2 The GSU noted several data gaps and contour errors on Report Figure 1-1 including: A) Incorrectly drawn trichloroethene (TCE) contour between wells 282-MW02 and 282-MW01 (no reason for separate lobes of TCE); B) Incorrect carbon tetrachloride (carbon tet) between 189-MW04 and 189-MW18 (no reason for separate lobes of carbon tet); C) Perchlorate contour incorrect at well 192-MW01; D) In general the extent of contamination is undetermined to the west of 188-MW01, northeast of 193-MW02, and southeast 189-MW08; E) High detection levels of carbon tet and other compounds were noted at several locations; and F) explanation of data qualifiers such as “S,” “Ja,” “ SJ,” and “J+1” were not provided. In general Figure 1-1 overly simplifies the extent of Site contamination. Recommendation: Correct Figure 1-1.

A) The trichloroethene (TCE) contour depicted represents the maximum contaminant level (MCL), not the edge of the extent of detectable TCE concentrations. Due to the TCE concentration detected at Well 193-MW03 (0.56 micrograms per liter), the separation of the two portions of the plume is warranted. B) The plumes will be redrawn to show the possible commingling of the carbon tet plumes. C) The plume will be redrawn to include well 192-MW02 within the perchlorate plume contour. D) Comment noted. These areas are not subject to the current treatability study. E) Comment noted. The treatability study is limited to the three target areas identified on Figure 1-1. Remedial alternatives for the entire site are being evaluated in the OU 5/10 Feasibility Study Report. F) Explanations for these data qualifiers will be added. Figure 1-1 is intended to present a general overview of the groundwater contamination at the Site, not a detailed evaluation of plume delineation and migration. Additional plume details are provided in the OU 5/10 RI Summary Report (Earth Tech, 2008).


The GSU notes an apparent ground water divide on Figure 1-1. In the northern half of the figure ground water moves to the northeast, in the southern half to the southeast. The Report does not discuss the reasons for this apparent ground water divide or the implications on contamination fate and transport at the Site. Recommendation: The Report should discuss how the different ground water flow directions would influence ISB efforts.

The apparent groundwater divide is localized and does not represent the regional groundwater flow direction. Furthermore, the hydraulic gradient at the Site is relatively flat. Since the proposed treatment areas are very small in scale relative to the entire site, any changes in groundwater flow direction across the entire site will not affect the treatability study. The impact of different groundwater flow directions and how it might influence full-scale ISB efforts will be considered when evaluating remedial alternatives in the OU5/10 Feasibility Study.

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Draft Remedial Investigation Summary Report North Base, Operable Unit 5/10, Edwards AFB, California, dated October 2007


Comment 4 The Report fails to mention of ethane was detected in the first phase of ISB at the Site.

Ethene, the end product of reductive dechlorination of chloroethenes, was detected during the first phase of ISB at the Site, as described in the Site 282 Bioremediation Treatability Study Report (Earth Tech, 2008). The second to last sentence on page 1-1 will be revised to read: “… concentrations of TCE, CT, and perchlorate, as well as their degradation products, significantly decreased with corresponding detections of ethene and methane (final end products of TCE and CT degradation, respectively) in wells that were affected by the treatment system…”


The Report does not state if Site-specific aquifer properties were directly measured in the field (such as a pump test). Recommendation: Please clarify this issue. Note, the GSU recommends field measurement of aquifer properties before starting ISB to better understand contaminant fate and transport.

Both groundwater slug tests and groundwater pumping tests were conducted in the vicinity of the treatability study locations. These tests are described in detail in Section 3.3.2 of the Site 282 Treatability Study Work Plan (Earth Tech, 2005).


On the bottom of page 3-7 of the Report, conditions favoring ISB are given to be more rigorous at treatment areas 1 and 2, than at 3. The GSU assumes this difference is due to the presence of only perchlorates at Area 3. Recommendation: Clarify this issue.

The last sentence on Page 3-7 will be revised as follows: “Because stronger reducing conditions are required at Treatment Areas 1 and 2 due to the presence of TCE, a 5 percent sodium lactate solution will be injected in those areas while a 4 percent sodium lactate solution will be injected in Treatment Area 3.

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Comment 7 Other ISB projects have provisions for supplemental bioaugmentation into monitoring wells if active distribution of DHC is not successful after a given time period (8 months). Recommendation: Consider provisions for supplemental bioaugmentation.

Supplemental bioaugmentation should not be necessary. Injections of electron donor will be performed after bioaugmentation and will serve to further distribute the injected culture. This effect has been documented at another site at Edwards AFB, as reported in the Remediation article cited below. Mora, R. H., T.W. Macbeth, T. Macharg, J. Gundarlahalli, H. Holbrook, and P. Schiff. 2008. “Enhanced Bioremediation Using Whey Powder for a Trichloroethene Plume in a High-Sulfate, Fractured Granitic Aquifer,” Remediation. 18:3:7-30.


The GSU disagrees that bromide is an innocuous ion as stated on page 4-4. Bromide can form trihalomethanes after water disinfection for municipal use. Brominated trihalomethanes are particularly carcinogenic and only a few gallons of bromide can contaminate thousands of gallons of ground water from the perspective of a water purveyor. However, as a further precaution, lithium salts may be better suited for tracer tests to limit the potential for the generation of carcinogenic products. Recommendation: Consider the use of lithium salts (or other tracer) as a future tracer compound.

Bromide has been used as a tracer for multiple treatability studies within OU 5/10, including the first phase of the Site 282 ISB TS, without appreciable formation of trihalomethanes. In the future, use of lithium salts or other alternative tracers will be considered.


Section 4.1.4 of the Report specified well slot and filter pack specifications for future wells. The Report should state that the selection of well slot and filter pack will be determined based on field conditions. The anticipated selection, however, can be given. Recommendation: Select well slot size and filter pack based on field determined conditions.

The following sentence will be inserted before the last sentence in the second paragraph: “The actual slot size and filter pack selection will be based on field-determined conditions.”

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Draft Remedial Investigation Summary Report North Base, Operable Unit 5/10, Edwards AFB, California, dated October 2007


Comment 10 On the bottom of Page 4-2, the formula for well grout is not given. The GSU recommends neat Portland cement with 6 gallons water per 90# sack. Recommendation: Specify grout mix.

The last sentence in the second paragraph will be revised as follows: “A bentonite seal will be placed in the 3-foot interval above the sand pack and the remaining well annulus will be grouted to the surface with a mixture composed of 95 percent Type II/V Portland cement and 5 percent bentonite.”


The Report states that in phase I of the ISB, well 189-MW01 did not show significant biodegradation. The GSU notes, however that high levels of vinyl chloride and cis-1,2-Dichloroethene – TCE breakdown products – were measured in this well. The GSU suspects that TCE contamination may be more extensive at this location. Recommendation: The text should note the presence of TCE breakdown products in this well and determine if contamination is more extensive (or isolated) at this location.

The low concentrations of cis-1,2-dichloroethene and vinyl chloride detected in this well are likely from biodegradation occurring in nearby monitoring wells. The contamination is not expected to be more extensive at this location. Instead, as mentioned in response to General Comment 3, the screen interval in this well is shallower than those of the surrounding wells, leading to a limited amount of electron donor being received, and, consequently, no significant biodegradation within the well screen interval.


The GSU noted another location for a pilot treatment area that is more contaminated than areas 2 and 3; near well 189-MW13 with TCE at 320 ug/L. Other nearby wells have TCE levels of 210, 190, and 56 ug/L, all much higher than in areas 2 or 3. Recommendation: Consider adding a fourth area (or reassigning areas).

This area is not suitable for the ISB pilot study, since it was the location of the previous NZVI pilot study. (Refer to response to General Comment 3.)

Notes: The California Regional Water Quality Control Board did not provide comments. DTSC = California Department of Toxic Substance Control U.S. EPA = United States Environmental Protection Agency

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