Final_SPEIM_Plan_RRA_Systems_Demo_1_Groundwater_OU_2005.pdf

Impact Area Groundwater Study Program

FINAL

System Performance and Ecological Impact Monitoring (SPEIM) Plan

Rapid Response Action Systems Demo 1 Groundwater Operable Unit

Camp Edwards Massachusetts Military Reservation

Cape Cod, Massachusetts

January 6, 2005 Prepared for:

U.S. Army Corps of Engineers New England District

Concord, Massachusetts for

U.S. Army / National Guard Bureau Impact Area Groundwater Study Program

Camp Edwards, Massachusetts

Prepared by:

AMEC Earth & Environmental, Inc Westford, Massachusetts

Contract No. DAHA92-01-D-0006

MMR-9300

MMR-9300

NOTICE

The United States Department of Defense, Department of the Army, funded wholly or in part the preparation of this document and work described herein under Contract DAHA92-01-D-0006. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

DISCLAIMER

This document has been prepared pursuant to government administrative orders (U.S. EPA Region I SDWA Docket No. I-97-1019 and 1-2000-0014) and is subject to approval by the U. S. Environmental Protection Agency. The opinions, findings, and conclusions expressed are those of the authors and not necessarily those of the Environmental Protection Agency.

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IMPACT AREA GROUNDWATER STUDY PROGRAM

FINAL

System Performance and Ecological Impact Monitoring (SPEIM) Plan

Rapid Response Action Systems Demo 1 Groundwater Operable Unit

Camp Edwards Massachusetts Military Reservation

Cape Cod, Massachusetts

January 6, 2005

U.S. Army Corps of Engineers New England District Concord, Massachusetts

U.S. Army / National Guard Bureau Impact Area Groundwater Study Program Camp Edwards, Massachusetts

Prepared for:

Prepared by:

AMEC Earth & Environmental, Inc.

Westford, Massachusetts

MMR-9300 Page iii

Final System Performance and Ecological Impact Monitoring Plan Rapid Response Action Systems Demo 1 Groundwater Operable Unit January 6, 2005

MMR-9300 Page v

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY ......................................................................................................... ES1

1.0 INTRODUCTION

1.1 PURPOSE

1.2 ORGANIZATION OF SPEIM PLAN

2.0 HYDROGEOLOGY AND CONTAMINANT DISTRIBUTION

2.1 GEOLOGY

2.2 HYDROGEOLOGY

2.3 CONTAMINANT DISTRIBUTION

3.0 EXTRACTION, TREATMENT AND RECHARGE SYSTEM DESIGNS

3.1 FRANK PERKINS ROAD RRA ETR SYSTEM DESIGN

3.1.1 Well Field Design

3.1.2 Treatment System Design

3.1.2.1 Estimated Influent Concentrations

3.1.2.2 RRA Treatment System Overview

3.1.2.3 RRA Treatment System Components

3.1.2.4 Effluent Criteria

3.2 PEW ROAD RRA ETR SYSTEM DESIGN

3.2.1 Well Field Design

3.2.2 Treatment System Design

3.2.2.1 Estimated Influent Concentrations

3.2.2.2 RRA Treatment System Overview

3.2.2.3 RRA Treatment System Components

3.2.2.4 Effluent Criteria

4.0 REMEDIAL SYSTEM PERFORMANCE MONITORING

4.1 HYDRAULIC MONITORING

4.1.1 Horizontal and Vertical Gradient Analysis

4.1.2 Monitoring Using Numerical Groundwater Model

4.1.3 Monitoring Schedule

4.1.4 Water Level Measurement Quality Assurance/Quality Control

4.2 TYPES OF MONITORING POINTS

4.2.1 Background Wells

PEW ROAD RA ETR SYSTEM

4.2.2 Plume Capture Analysis Wells

4.2.3 New Hydraulic Monitoring Wells

4.2.4 Proposed Toe of the Plume Sentinel Wells

4.2.4.1 Analysis for the Use of Existing Wells

4.2.4.2 Proposed Well Locations

4.3 ECOLOGICAL IMPACT MONITORING

4.4 PLUME CONCENTRATION MONITORING AND LONG TERM MONITORING

4.4.1 Plume Concentration Monitoring Strategy

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TABLE OF CONTENTS

Page

5.0 TREATMENT PLANT PERFORMANCE MONITORING

5.1 CONTAMINANT REMOVAL MONITORING

5.2 FRANK PERKINS ROAD SYSTEM MONITORING

5.3 PEW ROAD SYSTEM MONITORING

6.0 MONITORING AND REPORTING SCHEDULE

REFERENCES

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LIST OF FIGURES

1-1 Demo 1 Location Plan 2-1 Surficial Geologic Map 2-2 Regional Groundwater Elevation Contours 2-3 Perchlorate Distribution in Groundwater 2-4 Extent of Perchlorate and RDX in Groundwater 2-5 Perchlorate Plume Cross-Section - Frank Perkins Road RRA ETR 2-6 Perchlorate Plume Cross-Section - Pew Road RRA ETR 3-1 Frank Perkins Road RRA ETR System 3-2 Predicted Capture Zone: FPR RRA ETR System 3-3 Process Flow Diagram Frank Perkins Road RRA ETR System 3-4 Pew Road RRA ETR System 3-5 Predicted Capture Zone: Pew Road RRA ETR System 3-6 Process Flow Diagram Pew Road RRA ETR System 4-1 Hydraulic Monitoring Program: FPR RRA ETR System 4-2 Hydraulic Monitoring Program: Pew Road RRA ETR System 4-3 Proposed Sentinel Well Locations 4-4 Cross-Section G-G’ Perchlorate Distribution

LIST OF TABLES

2-1 Summary of COCs Detected in Groundwater 3-1 Extraction and Injection Well Details 3-2 Projected Range of COCs Influent Concentrations 3-3 Estimated Geochemical Influent Concentrations, Frank Perkins Road RRA ETR

System 3-4 Estimated Geochemical Influent Concentrations, Pew Road RRA ETR System 4-1 Wells in Hydraulic Monitoring Plan 4-2 Hydraulic Monitoring Schedule 4-3 Perchlorate Plume Concentration Monitoring 4-4 RDX Plume Concentration Monitoring 4-5 Plume Concentration Monitoring Schedule 5-1 Frank Perkins Road RRA ETR System Sampling Locations and Parameters for

Operational Monitoring 5-2 Pew Road RRA ETR System Sampling Locations and Parameters for Operational

Monitoring

LIST OF APPENDICES

Appendix A Extraction and Injection Well Construction Logs Appendix B Plume Concentration Monitoring Figures Appendix C Field Forms for Hydraulic and System Performance Monitoring Appendix D Response to Comments Letter (RCL) and Memorandum of Resolution (MOR)

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ACRONYMS AND ABBREVIATIONS

AMEC AMEC Earth and Environmental, Inc.

AO3 Administrative Order Number 3 (SDWA 1-2000-0014) BBM Buzzards Bay Moraine bgs below ground surface bwt below water table COC Contaminant of Concern Demo 1 Demolition Area DO dissolved oxygen EFF effluent EPA or USEPA United States Environmental Protection Agency ETR Extraction, Treatment, and Recharge EW extraction well identification number FS Feasibility Study ft feet or foot FPR Frank Perkins Road GAC Granular Activated Carbon gpm gallons per minute IAGWSP Impact Area Groundwater Study Program INF influent ITE Innovative Technology Evaluation IW-# injection well identification number IX ion exchange LTGM Long Term Groundwater Monitoring MADEP Massachusetts Department of Environmental Protection µg/L micrograms per liter mg/L milligrams per liter MMR Massachusetts Military Reservation MPP Mashpee Pitted Plain MW monitoring well identification number ND non-detect NGVD National Geodetic Vertical Datum ORP oxidation-reduction potential OU operable unit PR Pew Road QA/QC quality assurance/quality control RDX hexahydro-1,3,5-trinitro-1,3,5-triazine RRA Rapid Response Action SDWA Safe Drinking Water Act SM Sandwich Moraine SPEIM System Performance and Ecological Impact Monitoring TAT turn-around time TNT 2,4,6-trinitrotoluene TOC total organic carbon TSS total suspended solids USACE United States Army Corps of Engineers

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EXECUTIVE SUMMARY

This System Performance and Ecological Impact Monitoring (SPEIM) Plan is targeted at monitoring the effectiveness of the Rapid Response Action (RRA) for the Demolition Area 1 (Demo 1) contaminant plume and evaluating potential ecological impacts that could be caused by the RRA Extraction, Treatment, and Recharge (ETR) system. The RRA for the Demo 1 Groundwater Operable Unit (OU) includes interim actions by the U.S. Army/National Guard Bureau’s Impact Area Groundwater Study Program (IAGWSP) to remediate groundwater contamination emanating from Demo 1 at Camp Edwards.

Demo 1 is located north of Pocasset Forestdale Road and south of the Impact Area at Camp Edwards, west of Turpentine Road and east of Frank Perkins Road. Demolition training and explosive ordnance disposal at Demo 1 included the destruction of various types of ordnance using explosive charges of C4, 2,4,6-trinitrotoluene (TNT), and detonation cord from the mid 1970’s to the late 1980’s. The predominant explosive compounds used in demolition munitions are hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) followed by TNT. Perchlorate has also been detected in groundwater. Perchlorate (ClO4

-) originates as a contaminant in the environment from the solid salts of ammonium, potassium, or sodium perchlorate. Ammonium and potassium perchlorate are manufactured for use as the oxidizer component and primary ingredient in solid propellant for rockets, missiles, and fireworks, in addition to being used in some delay compositions, flares, signaling devices, other pyrotechnics, smokes, and tracers.

Seven explosive and propellant compounds (RDX, TNT, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, 2-amino-4,6-dinitrololuene, 4-amino-2,6-dinitrotoluene, perchlorate and 2,4-dinitrotoluene) have been consistently detected in groundwater and are identified as the contaminants of concern (COCs) in groundwater for the Demo 1 Groundwater OU. These contaminants are all directly related to past demolition and disposal activities and have been detected in soil at Demo 1.

The measured extent of detectable concentrations of perchlorate in the plume is estimated at approximately 9,200 feet (ft) long and 1,400 ft wide based on data collected through March 2004. The measured extent of the detectable concentrations of RDX in the plume is estimated at approximately 6,600 ft long and 650 ft wide. The measured extent of the 1 microgram per liter (µg/L) perchlorate plume is estimated at 8,460 ft long and 850 ft wide. The RDX plume and all other COC plumes are contained within the perchlorate plume.

The purpose of the groundwater RRA is to begin removing dissolved contaminant mass from the plume while continuing to evaluate the feasibility of comprehensive remedial actions and determining a permanent solution. The RRA includes installation of two remedial systems, one at Frank Perkins Road and the other at Pew Road. The overall objective of the RRA ETR systems at Frank Perkins Road and Pew Road is to provide hydraulic capture of the majority of the groundwater plume to control further migration and to initiate removal and treatment of dissolved contaminant mass contained within the plume.

The major components of the Frank Perkins Road RRA ETR system include:

• A single extraction well pumping at a rate of approximately 220 gallons per minute (gpm)

• An ex-situ treatment process consisting of granular activated carbon (GAC) media and ion exchange (IX) resin to treat perchlorate and explosives, with the option of using other media in the future

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• Two injection wells installed laterally north and south of the plume with the screened interval below the plume to return treated water to the aquifer

The major components of the Pew Road RRA ETR system include:

• A single extraction well pumping at a rate of approximately 100 gpm

• An ex-situ treatment process consisting of GAC media to remove low levels of perchlorate and explosives (if detected)

• A single injection well located to the south of the plume (outside the zone of influence of the extraction well) to return treated water to the aquifer

Construction of the interim action components for the Frank Perkins Road and Pew Road RRA ETR systems was completed in August 2004, and startup of the RRA ETR systems was conducted in September 2004.

The purpose of this RRA Groundwater SPEIM Plan is to outline procedures to monitor the effectiveness of the Frank Perkins Road and Pew Road RRA ETR systems. This plan outlines specific activities proposed to demonstrate the extent of plume capture upgradient of the extraction well for each of the RRA ETR systems. Additional monitoring activities are focused on plume concentration monitoring to assess contaminant distribution. In addition, monitoring at the treatment systems will include influent and effluent sampling to demonstrate that the treated water being recharged back into the aquifer through the injection wells is below the method detection limit of 0.35 µg/L for perchlorate and the reporting limit of 0.25 µg/L for RDX.

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1.0 INTRODUCTION

This System Performance and Ecological Impact Monitoring (SPEIM) Plan for the Rapid Response Action (RRA) at Demolition Area 1 (Demo 1) presents a program for monitoring the effectiveness of two separate remedial Extraction, Treatment, and Recharge (ETR) systems. One is located at Frank Perkins Road and the other at Pew Road. Monitoring activities will be conducted to determine the extent of capture of the perchlorate and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) plumes upgradient of Frank Perkins Road and Pew Road. Additional monitoring activities will assess the RRA ETR systems’ effectiveness in treating the extracted groundwater prior to recharge back to the aquifer through injection wells and assessing potential ecological impacts.

A detailed description of the RRA system designs is contained in the RRA Plan, Demo 1 Groundwater OU (AMEC 2003a). Final modifications to the injection well design and flow rates for the Frank Perkins Road extraction well are found in Project Note 8010, Revised Screen Elevation of Injection Wells, Frank Perkins Road ETR system (USACE 2003). Final modifications to the treatment system design and components are found in the Memorandum of Resolution for the Draft RRA Plan, Demo 1 Groundwater Operable Unit (OU) (AMEC 2004). A brief description of the RRA ETR systems is presented in Section 3.0 of this plan.

Demo 1 is located south of the Impact Area as shown on Figure 1-1. Explosives and perchlorate in groundwater are the result of historic open burn and detonation activities, munitions burning and/or burial, and demolition training activities conducted at Demo 1 from the mid 1970’s to the late 1980’s. During that time, explosive materials and propellants from other ranges were disposed of by detonation, burning, and/or burial at Demo 1.

This work has been conducted pursuant to United States Environmental Protection Agency (EPA) Administrative Orders under the Safe Drinking Water Act (SDWA) 1-97- 1019 and 1-2000-0014 (AO3).

1.1 Purpose

The overall objective of the RRA ETR systems at Frank Perkins Road and Pew Road is to provide hydraulic capture of the majority of the groundwater plume to control further migration and to initiate removal and treatment of dissolved contaminant mass contained within the plume. By controlling the spread of the plume, the RRA ETR systems will limit the ultimate size of the comprehensive remedy and associated effects on natural resources.

The primary objectives of the RRA ETR interim actions at Frank Perkins Road and Pew Road are presented below.

Frank Perkins Road – Capture the highest contaminant (explosives and perchlorate) concentrations within the plume that are located upgradient of Frank Perkins Road to prevent further migration beyond Frank Perkins Road.

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Pew Road – Eliminate or significantly reduce the degree of hazard posed by continued migration of the portion of the perchlorate and RDX plumes downgradient of Frank Perkins Road and limit the ultimate volume of measurable perchlorate concentrations (greater than the analytical reporting limit of 1.0 microgram per liter [µg/L]). In addition, the Pew Road location will provide the Impact Area Groundwater Study Program (IAGWSP) with valuable information regarding the long-term treatment of groundwater containing low concentrations of perchlorate with granular activated carbon (GAC) media.

This SPEIM Plan specifies monitoring activities to meet the following objectives:

• Evaluate hydraulic conditions to assess the effectiveness of the RRA ETR systems on the contaminant plume upgradient of Frank Perkins Road and Pew Road

• Evaluate the RRA ETR systems impact on ecological receptors, specifically the effect of the Frank Perkins Road system on groundwater elevations at Opening Pond

• Evaluate the nature and extent of perchlorate and RDX concentrations in groundwater and trends over time

• Assess the treatment system’s performance at removing perchlorate and RDX from groundwater prior to recharge back to the aquifer through injection wells

• Assess changes in general groundwater chemistry throughout the treatment process

The RRA systems are estimated to operate from September 2004 through Spring 2007.

In 2007, the two extraction wells and three injection wells utilized in the RRA will be incorporated into the comprehensive remedy for the Demo 1 Groundwater OU.

1.2 Organization of SPEIM Plan

The hydrogeologic framework and nature and extent of contaminants in groundwater are presented in Section 2. A general description of the Frank Perkins Road and Pew Road RRA ETR systems is presented in Section 3. Proposed monitoring activities to assess the RRA ETR systems hydraulic control effectiveness, changes in contaminant distribution within the plume and ecological impacts are presented in Section 4. Details concerning in-plant monitoring to assess the contaminant removal efficiency of the treatment process and to determine effluent compatibility with groundwater are presented in Section 5.

2.0 HYDROGEOLOGY AND CONTAMINANT DISTRIBUTION

2.1 Geology

Three extensive sedimentary units dominate the regional geology: the Buzzards Bay Moraine (BBM), the Sandwich Moraine (SM), and the Mashpee Pitted Plain (MPP). The Demo 1 contaminant plume is located within the MPP and the BBM (Figure 2-1). The

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MPP consists of fine to coarse-grained sands and gravel and forms a broad flat outwash plain south and east of the two moraines. The BBM and SM are distinct ridges with a hummocky topography and commonly include lenses of silt and clay or large boulders interbedded with the sands.

The Demo 1 depression (a dry kettle hole) is located within the MPP (Figure 2-1). The Demo 1 plume originates at the Demo 1 depression and extends west of Frank Perkins Road into the more stratified BBM.

Within the MPP the water table is at a depth of approximately 80 feet (ft) to water and bedrock is generally at a depth of 300 ft. In the moraine, due to the hummocky land surface, depths to the water table are highly variable and range up to 150 ft, (AMEC 2003b). The top of bedrock elevation is assumed to rise slightly toward the west.

2.2 Hydrogeology

A single groundwater flow system underlies western Cape Cod, including the Massachusetts Military Reservation (MMR). The aquifer system is unconfined (i.e., it is in equilibrium with atmospheric pressure and is recharged by infiltration from precipitation). The ocean bounds the aquifer on three sides, with groundwater discharging into Nantucket Sound on the south, Buzzards Bay on the west, and Cape Cod Bay on the north (Figure 2-2). The Bass River in Yarmouth forms the eastern lateral aquifer boundary. The high point of the water table occurs as a groundwater mound beneath the eastern portion of Camp Edwards, north and east of Demo 1 (Figure 2-2). The top of this mound is at an elevation of approximately 66 ft under long-term average conditions (based on groundwater elevations measured in May 2002).

Groundwater flow radiates outward from this mound.

The Demo 1 depression is located approximately 1½ miles west of the groundwater mound and 4 miles east of Buzzards Bay (Figure 2-2). Groundwater flow in the Demo 1 plume is west-southwest toward the Bourne area and ultimately Buzzards Bay.

Groundwater elevations in the plume range from approximately 64 to 50 ft (Figure 2-3).

The horizontal groundwater gradient in the Demo 1 plume becomes steeper as it crosses into the BBM. This gradient is approximately 0.0006 ft/ft between the source depression area and Frank Perkins Road, increasing to 0.0023 ft/ft at the downgradient toe of the plume toward the middle of the moraine (Figure 2-3). Depths to water vary from 45 ft in the depression to over 140 ft in downgradient portions of the plume.

Flow in the Demo 1 plume is mostly horizontal except at the downgradient end of the plume where there are some downward and upward gradients associated with lower permeability zones. Hydraulic conductivities are generally very high especially in the upgradient portions of the plume.

Surface water bodies near the Demo 1 plume include Opening Pond (Figure 2-3) on the northern edge of the central part of the plume, and North Pond located approximately 1,300 ft downgradient of the toe of the plume (MW-258). Opening Pond is the only surface water body or potentially sensitive area in close proximity to the RRA systems to

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MMR-9300 Page 4 warrant monitoring for potential ecological impacts due to hydraulic effects. This is further discussed in Section 4.3.

2.3 Contaminant Distribution

The Final Technical Memorandum 01-2, Demo 1 Groundwater Report (AMEC 2001a) established contaminants of concern (COCs) for groundwater at Demo 1 in accordance with the Draft Final COC Identification Process (Ogden 2000). The results of the contaminants of potential concern screening, risk evaluation and risk management process (AMEC 2001a) identified the following six compounds as COCs for the Demo 1 Groundwater OU:

• RDX

• 2,4,6-trinitrotoluene (TNT)

• octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)

• 4-amino-2,6-dinitrotoluene (4A-DNT)

• 2-amino-4,6-dinitrotoluene (2A-DNT)

• 2,4-dinitrotoluene (2,4-DNT)

In addition to these compounds, perchlorate has been identified as a COC at Demo 1.

Perchlorate, for which groundwater was not analyzed prior to August 2000, has been repeatedly detected in groundwater at Demo 1. Table 2-1 presents the sampling dates and detected concentrations of the COCs by monitoring well at Demo 1 through March 5, 2004. Figure 2-3 depicts perchlorate concentrations in plan view. Figure 2-4 depicts the extent of perchlorate and RDX that make up the Demo 1 plume.

RDX and TNT have been detected in groundwater at Demo 1 at maximum concentrations of 370 µg/L and 16 µg/L, respectively. The USEPA Lifetime Health Advisory for both RDX and TNT in drinking water is 2 µg/L. Perchlorate has been detected in groundwater at Demo 1 at a maximum concentration of 500 µg/L. There is no Federal Maximum Contaminant Level or EPA Lifetime Health Advisory for perchlorate. A “relevant standard” of 1.5 µg/L had been provided by EPA (USEPA 2001) for the purposes of developing and evaluating alternatives in feasibility studies required by AO3, however, this was rescinded in February 2003.

In January 2003, EPA (EPA 2003) issued a memorandum re-affirming 1999 interim guidance that results in a provisional risk-based standard range from 4 to 18 µg/L for perchlorate. The range (4-18 µg/L) is considered to be protective based on recent, ongoing analyses and taking into account the most sensitive receptors, and therefore no additional adjustment for childhood exposure is needed.

In April 2002, the Massachusetts Department of Environmental Protection (MADEP) issued a ‘Massachusetts Interim Drinking Water Advice for Perchlorate’ (MADEP 2002) to the Bourne Water District in response to the low concentrations of perchlorate detected in groundwater samples collected from wells within the Monument Beach Well Field. The MADEP recommended, “Pregnant women, infants, children up to the age of twelve, and individuals with hypothyroidism avoid drinking water containing concentrations of perchlorate exceeding 1 µg/L”. In addition, the MADEP plans to establish a numeric standard for perchlorate in Spring 2004. The Army has agreed to

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MMR-9300 Page 5 meet numeric standards or remediate to a level below such standards if feasible, where such standards are applicable or relevant and appropriate, and promulgated or adopted in the future.

The measured extent of the 1 µg/L perchlorate plume is estimated at approximately 8,460 ft long. The measured maximum width of the 1 µg/L perchlorate plume is in the Frank Perkins Road area and is estimated at approximately 850 ft. The measured perchlorate plume width at Pew Road is approximately 500 ft. The maximum measured extent of the RDX plume is estimated at 6,600 ft long with an estimated width of approximately 650 ft. The RDX plume and all other COC plumes are contained within the perchlorate plume. Figures 2-5 and 2-6 present cross-sections of the perchlorate plume at Frank Perkins Road and Pew Road, respectively.

3.0 EXTRACTION, TREATMENT AND RECHARGE SYSTEM DESIGNS

ETR was selected as the remedial approach for the RRA because it was likely to be compatible with future comprehensive remedial actions based on the Draft Feasibility Study (FS) (AMEC 2001b) and input from the EPA, MADEP and the Impact Area Review Team.

The Frank Perkins Road and Pew Road RRA ETR systems were developed independently without consideration of the hydraulic effects of the other system. That is, the design flow rates that provide suitable capture at each location were optimized as if each well was the only extraction well in the plume. For two pumping wells along a flow path, much of the water outside the upgradient capture zone that is not captured by the upgradient well is ultimately captured by the downgradient pumping well. Therefore, a wider portion of the aquifer at the upgradient location is ultimately captured, albeit by the downgradient extraction well. However, it was considered conservative to design the Frank Perkins Road extraction well location and flow rate to fully contain the upgradient portion of the plume without additional capture provided by a downgradient well. The combined effects of multiple extraction wells have been considered in the development of remedial alternatives in the Final FS.

3.1 Frank Perkins Road RRA ETR System Design

The following sections present the Frank Perkins Road well field design and the treatment system design.

3.1.1 Well Field Design

The Frank Perkins Road well field was designed using the minimum number of wells to achieve the objective of maintaining hydraulic control of the high concentration area of the perchlorate plume upgradient of Frank Perkins Road. The design was completed using a 3D numerical groundwater flow model as documented in the RRA Plan (AMEC 2003a). Since completion of the RRA Plan, the groundwater model was updated (Dec.

2003) and used to develop well field designs for Revised Draft FS (AMEC 2004b) for the Demo 1 Groundwater OU. Numerical modeling results conducted for the RRA Plan indicate that a single extraction well (EW-D1-1) coupled with two injection wells (IW-D1-1

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MMR-9300 Page 6 and IW-D1-2) is capable of containing the plume. These locations are along Frank Perkins Road and generally aligned crossgradient. EW-D1-1 is located roughly in the center of the plume (Figure 3-1). The location and screen length (90 ft) was set to span the full thickness of the plume at Frank Perkins Road. The elevation of the screen is from 34 to –56 ft National Geodetic Vertical Datum (NGVD) (Figure 2-5).

The injection wells are located on the northern (IW-D1-1) and southern (IW-D1-2) edges of the perchlorate plume. The original design location for these injection well screens was 100 ft outside the plume with a vertical span equal to the same elevations as the extraction well. However, during installation of these wells, very low levels of perchlorate (less than 1 µg/L) were detected in one or more profile samples at both of the injection well locations. Based on these detections, it was agreed by the USEPA and the MADEP to set the screen for the injection wells at deeper elevations (beneath the plume) to avoid bifurcating these low levels of perchlorate (USACE 2003). Therefore, the screen elevation of IW-D1-1 was set at elevation -54 to -154 ft and the screen elevation of IW- D1-2 was set at elevation –69 to –169 ft NGVD (Figure 2-5). The proposed flow rate of 220 gallons per minute (gpm) is higher than originally specified in the RRA Plan (AMEC 2003a). The extraction rate was increased at the request of EPA and MADEP to compensate for the change in injection well screen elevations and corresponding slight reduction in capture efficiency. Extraction well and injection well construction details are presented in Table 3-1. Well construction logs for these wells are presented in Appendix A.

Figure 3-2 illustrates the modeled plan view potentiometric contours and resulting streamlines that form the capture zone for the proposed system. Due to the high hydraulic conductivity of the aquifer in this area, predicted draw down at the extraction well is less than 5 ft. The magnitude of mounding in the injection wells should be less than the draw down in the extraction well as the injection rate at each location will be half the total extraction rate or 110 gpm.

As discussed in Section 1.0, the Frank Perkins Road RRA ETR system was designed without consideration for the downgradient Pew Road RRA ETR system. While it is understood that upgradient capture zones may be augmented by downgradient pumping, due to the long advective groundwater travel time from Frank Perkins Road to Pew Road (even under pumping conditions), by the time there was a combined effect on capture zones, the comprehensive remedy would be implemented. Therefore, it was conservative to perform the Frank Perkins Road RRA ETR design independently.

3.1.2 Treatment System Design

The following sections include discussion of the Frank Perkins Road treatment system design, including estimated influent concentrations, an overview of the treatment system operation, treatment system components and effluent criteria.

3.1.2.1 Estimated Influent Concentrations

Estimated influent concentrations were derived for the Frank Perkins Road extraction well using the numerical groundwater model. The model was setup to provide extracted water concentrations of perchlorate and RDX at weekly intervals. Model predicted

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MMR-9300 Page 7 concentrations are calculated at the location of the well and incorporate the predicted flow and concentration by model layer. Please note that these calculations are based on plume shells presented in the Demo 1 Groundwater Report Addendum, which were based on analytical data current through April 2003 (AMEC 2003b).

The predicted initial influent concentrations of perchlorate are approximately 30 to 50 µg/L, decreasing to less than 10 µg/L in roughly one year. Concentrations of perchlorate after one year continues to decrease, but at a slower rate. Predicted perchlorate concentrations at the end of four years were approximately 5 µg/L. Predicted RDX concentrations are approximately 5 µg/L decreasing to 1 µg/L. These predicted influent concentrations for perchlorate and RDX at the Frank Perkins Road RRA ETR are presented on Table 3-2.

Based on samples from monitoring wells around Frank Perkins Road a summary of expected influent concentrations of standard water quality parameters is presented in Table 3-3.

3.1.2.2 RRA Treatment System Overview

The Frank Perkins Road Treatment System will consist of containerized mobile treatment units. The design configuration for the treatment system is driven by the size of vessels that fit within the containerized mobile treatment units. To treat a flow rate of approximately 220 gpm, the Frank Perkins Road Treatment System will consist of three containerized mobile treatment units. Each mobile treatment unit will accommodate an average flow rate of 73 gpm with the flexibility to accommodate up to 100 gpm.

The treatment units will be housed in 8-foot by 40-foot containers, similar to ones used to transport goods. The containers will consist of a steel or aluminum-shell construction, insulated on all four sides as well as the ceiling. The flooring will be constructed with a water collection system to abate leakage or releases within the treatment system. The containers will be supported by an engineered soil/geogrid foundation. Upon system removal, this type of foundation will reduce future demolition costs relative to a concrete foundation; yet still provide more than adequate support for the container.

The treatment train within each container will use GAC media (2,000 pounds) followed by ion exchange (IX) resin (vessels can accommodate approximately 40 cubic ft) followed by GAC media (2,000 pounds). The GAC and IX vessels would be used in conjunction with additional system components as summarized in the process flow diagram (Figure 3-3).

The containers will house the filtration system, GAC and IX units, and backwash system.

The backwash system includes a backwash water tank and backwash pump that shall be sized to fit into the confines of the containerized mobile treatment. The electrical connection to the treatment components and all other power-based equipment in the building will be housed in locked steel cabinets. An independent electrical cabinet will contain all the wiring for the connections to the main power supply, as well as the extraction/injection wells and exterior lighting. The container construction will meet

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MMR-9300 Page 8 applicable codes and regulations including the Massachusetts Building Code and the National Electrical Code.

The system is designed to be portable. Piping and other connections between the containers will be detachable, such that containers can be transported to other locations for treatment.

3.1.2.3 RRA Treatment System Components

Pretreatment

Pretreatment is often necessary in groundwater extraction and treatment systems to alter the chemistry of the influent water to prevent fouling in the treatment process.

Pretreatment is commonly used at other treatment systems at MMR to prevent particulate and biological-based iron fouling. However, those systems function under different geochemical conditions (i.e., iron and manganese in groundwater) than at the Frank Perkins Road RRA ETR system. To assess the potential for fouling at the Frank Perkins Road RRA ETR, geochemical parameters were assessed from surrounding monitoring wells. These parameters are summarized in Table 3-3.

Based on the results of geochemical analyses on samples collected from the mid-range of the Demo 1 plume, minimal concentrations of iron (0.027 milligrams per liter [mg/L]) and manganese (0.005 mg/L) are predicted in the extracted water for the Frank Perkins Road RRA ETR system. Pretreatment should typically be implemented to abate fouling when iron concentrations exceed 5 mg/L and pretreatment is not necessary when concentrations are below 1 mg/L (US Filter 2002). The low concentrations detected in monitoring wells in the mid-range of the Demo 1 plume combined with the aerobic nature of the water in the Demo 1 plume indicate that fouling should not present a problem for the treatment system. However, pretreatment utilizing a filtration system (e.g., bag filter) will be incorporated in the Frank Perkins Road Treatment System to filter out fines that may be entrained in the extracted water.

In each containerized mobile treatment unit, the filtration system will consist of one set of two bag filters in parallel, capable of accommodating the maximum flow rate through the containerized mobile treatment unit. The filtration system will have a bypass to allow operation of the treatment system without the bag filters if it is considered desirable.

Treatment Media

The initial treatment media for the Frank Perkins Road Treatment System will consist of GAC media and IX resin. The conceptual design for the Frank Perkins Road RRA ETR System consists of three containers with a three-step treatment train in each container.

Each treatment train will use GAC media (2,000 pounds) followed by IX resin (40 ft3 vessels) followed by GAC media (2,000 pounds).

The treatment for explosives will be through the primary GAC vessels in each of the three containers. The treatment for perchlorate will be through vessels containing IX resin located after the primary GAC vessels. The initial IX resin for the Frank Perkins Road Treatment will be a Nitrate Selective Resin. The secondary GAC vessel will be

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MMR-9300 Page 9 utilized as a polishing unit to ensure that if there were breakthrough of the explosives from the primary GAC vessel and/or perchlorate from the IX resin unit, it would be captured by the secondary GAC vessel prior to discharge.

The treatment train utilizes two GAC units for explosive absorption/adsorption, as the selected IX resin does not sorb non-polar molecules (such as explosives). As a result, the primary GAC vessels would have to be changed out as soon as practical after explosives breakthrough occurs after this unit. The IX resin change-outs will be initiated when perchlorate is detected in the effluent of the IX unit. Although the IX media will be replaced upon detection of perchlorate if it does occur, the GAC media in the secondary GAC vessel will adsorb any perchlorate that does break through.

The IAGWSP has completed laboratory-scale studies, and plans to complete additional field scale studies as part of the Innovative Technology Evaluation (ITE) studies. Field scale studies are currently being performed using GAC media that has been coated with an ionic monomer (tailored GAC) and two types of IX resins. Other ITE lab-scale studies at Penn State have evaluated virgin GAC and currently there are ITE studies being performed using virgin GAC with groundwater from the Central Impact Area (CIA). The ITE studies and preparation of the final report, on both IX resin and tailored-GAC media, were completed in July and October 2004 respectively. The studies include adsorption testing for water containing only low levels of perchlorate. These studies will provide additional information, which will determine the efficacy and precise design parameters of the comprehensive remedy system. The results of the ITE studies will be used to gain regulatory approval for the use of tailored-GAC media and IX resin (if successful), for the treatment of low levels of perchlorate and other COCs in the MMR groundwater. Results of the ITE studies would be utilized for the selection of media during change-outs.

Upon completion of the ITE studies, the selection of the replacement media for the Frank Perkins Road RRA ETR System will be evaluated. The system is designed such that any replacement media could be utilized with existing treatment system equipment with slight modifications. The evaluation and any proposed changes would be provided to the EPA and MADEP for review and approval prior to implementation.

The ITE study results and initial performance evaluations of primary GAC vessels will allow for a logical selection of appropriate replacement media – whether it is a virgin GAC, tailored GAC or IX media. In addition, utilizing GAC as the primary vessels in the treatment system for the initial operations of the Frank Perkins Road Treatment System will provide useful information on the future use of GAC for treatment of low levels of perchlorate and other COCs at MMR.

3.1.2.4 Effluent Criteria

Treatment system effluent limits were established in compliance with federal, state and local regulations. This led to the development of treatment objectives for process operations. Regulatory requirements for recharge of effluent relative to COCs and other water quality parameters for the RRA ETR systems are summarized in Table 3-3.

GAC media change-outs in the primary GAC vessels will be initiated when explosives are detected at a concentration above the reporting limit of 0.25 µg/L in the effluent of

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MMR-9300 Page 10 the primary GAC vessels. The IX change-outs will be initiated when perchlorate is detected at a concentration above the method detection limit of 0.35 µg/L in the effluent of the IX unit. Section 5.1.2 presents additional parameters that will be monitored as part of the Frank Perkins Road system performance monitoring.

3.2 Pew Road RRA ETR System Design

The following sections present the Pew Road well field design and the treatment system design.

3.2.1 Well Field Design

In the RRA Plan, analytical modeling results indicate that a single extraction well (EW- D1-2) coupled with a single injection well (IW-D1-3) are capable of containing the width of the 1 µg/L perchlorate plume as stated as an objective of the Pew Road RRA ETR system for the RRA Design. These extraction and injection well locations are along Pew Road and are generally aligned crossgradient. Due to uncertainty in the plume boundaries during the period of the RRA design, one injection well was installed far enough away from the extraction well to have little or no impact on the flow paths within the plume. The layout of the extraction and injection well locations is presented on Figure 3-4. A cross-section of the plume at Pew Road with the location and depth of the extraction well and injection well is presented on Figure 2-6. Extraction well and injection well construction details are presented in Table 3-1.

The 3D numerical model developed during the FS was not completed for the Pew Road area during the RRA design period. Therefore, the Pew Road system extraction rate was determined analytically based on measured hydraulic conductivity and measured gradients. The resulting flow rate indicated 100 gpm was adequate to capture the width of the 1 µg/L plume. Since completion of the RRA Plan, the groundwater model was updated (Dec. 2003) and used to develop well field designs for Revised Draft FS (AMEC 2004b) for the Demo 1 Groundwater OU. As interpreted from additional data collected at Demo 1, including chemical monitoring, borehole gamma logging, wellpoint hydraulic conductivity data and potentiometric data, the newly calibrated subregional Demo 1 groundwater model represents a more detailed analysis of plume dynamics in the Pew Road area. Once calibrated, the model was run with the design flow rate of 100 gpm at the Pew Road location as previously recommended.

Modeling results indicate that the predicted capture zone for the Pew Road well at 100 gpm, though smaller than that predicted by the more simplified analytical solution, still contains the width of the 1 µg/L perchlorate plume. Therefore, the design flow rate of 100 gpm has been maintained. Figure 3-5 illustrates the potentiometric contours and resulting streamlines that form the capture zone for the proposed Pew Road RRA ETR system. Predicted draw down at the extraction well is less than 5 ft. Predicted mounding at the injection well is less than 7 ft.

EW-D1-2 is located along Pew Road roughly in the center of the plume adjacent to MW-

211. The location and screen length (40 ft) were set within the plume interval identified at MW-211 (165 to 215 ft below ground surface [bgs]). A boring log with well screen

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MMR-9300 Page 11 installation details is presented in Appendix A. Since the top 5-10 foot section of the plume interval is approximated and the grain size evaluation for this top section indicated an extremely permeable zone, the top of the filter pack was set at 170 ft bgs and the well screen was set from 175-215 ft bgs. With this well construction design, installation of a short section of a wide-slot screen (170 – 175 ft bgs) was avoided (partially limiting input of clean water above) and the screen still spans the highest concentrations of the plume.

Recent data indicate that perchlorate concentrations are non-detect (ND) in the upper two screens (MW-211M3 and MW-211M2) at MW-211 and are greater than 5 µg/L in the lower screen (MW-211M1). Review of Figure 2-6 indicates the Pew Road extraction well screen is located in the ideal location to minimize flow and extract the highest concentration portion of the plume. The elevation of the screen is from 24 to –16 ft

NGVD.

IW-D1-3 is located south of the plume at the junction of Estey Road and Pew Road approximately 500 ft southwest of MW-221 (Figure 3-4). Since only one injection well is used, the screened interval was set to span the plume interval and an equivalent thickness beneath the plume. This was done to reduce the unbalanced hydraulic impact of single lateral injection well on the plume. The screen elevation for this injection well is 38 to –42 ft NGVD. Extraction well and injection well construction details are indicated in Table 3-1. Well construction logs for these wells are found in Appendix A.

3.2.2 Treatment System Design

The following sections include discussion on the Pew Road treatment system design, including estimated influent concentrations, an overview of the treatment system operation, treatment system components and effluent criteria.

3.2.2.1 Estimated Influent Concentrations

As discussed in Section 3.1.2.1 estimated influent concentrations were derived for the Pew Road extraction well using the numerical groundwater model. Results showed that influent concentrations of perchlorate for the Pew Road extraction well are predicted to range from approximately 0.35 to 5 µg/L and average approximately 1.0 µg/L. The predicted influent concentration for perchlorate at the Pew Road RRA ETR is presented on Table 3-2.

Based on samples from monitoring wells around Pew Road a summary of expected influent concentrations of standard water quality parameters is presented in Table 3-4.

3.2.2.2 RRA Treatment System Overview

The Pew Road treatment system will consist of a single mobile containerized treatment unit to treat a flow rate of approximately 100 gpm. The design of the mobile containerized treatment unit is similar to the Frank Perkins Road system presented in Section 3.1.2.2, however IX resin will not be used as part of the treatment methodology.

The treatment train within the container will use a series of three pairs of vessels containing GAC media (each vessel containing 1,000 pounds of GAC). The GAC

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MMR-9300 Page 12 vessels will be used in conjunction with additional system components as summarized in the process flow diagram (Figure 3-6).

3.2.2.3 RRA Treatment System Components

Pretreatment

To assess the potential for fouling at the Pew Road RRA ETR, geochemical parameters were assessed from surrounding monitoring wells. These parameters are summarized in Table 3-4.

Based on the results of geochemical analyses on samples collected from the mid-range of the plume in the Pew Road area, minimal concentrations of iron (0.042 mg/L) and manganese (0.015 mg/L) are predicted in the extracted water for the Pew Road RRA ETR system (Table 3-4). Pretreatment utilizing a filtration system (e.g., bag filter) will also be incorporated in the Pew Road Treatment System to filter out fines that may be entrained in the extracted water. This filtration system may be bypassed based on actual operational performance.

Treatment Media

The initial treatment media for the Pew Road treatment system will consist of GAC media. The conceptual design for the Pew Road RRA ETR System consists of a three-step treatment train in a single container. The treatment train will use a series of three pairs of GAC media vessels with each pair containing a total of 2,000 pounds of GAC media.

The treatment for perchlorate and explosives (if detected) will be through the primary and secondary GAC vessels. The third GAC vessel will be utilized as a polishing unit to ensure that if there were breakthrough of the perchlorate and/or explosives (if detected) from the primary and secondary GAC vessels, it would be captured by the third GAC vessel prior to discharge.

The GAC change-outs will be initiated when perchlorate and/or explosives are detected in the effluent of the second GAC vessel pair. Although the GAC media will be replaced upon detection of perchlorate or explosives (if detected), the GAC media in the third GAC vessel will adsorb any perchlorate or explosives that breakthrough.

Similar to the Frank Perkins Road system, upon completion of the ITE studies, the selection of the replacement media for the Pew Road RRA ETR system will be evaluated. The system is designed such that any replacement media could be utilized with existing treatment system equipment with slight modifications. The evaluation and any proposed changes would be provided to the EPA and MADEP for review and approval prior to implementation.

3.2.2.4 Effluent Criteria

Treatment system effluent limits were established in compliance with federal, state and local regulations. This led to the development of treatment objectives for process

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MMR-9300 Page 13 operations. Regulatory requirements for recharge of effluent relative to COCs and other water quality parameters for the RRA ETR systems are summarized in Table 3-3.

GAC media change-outs in the primary and secondary GAC vessels will be initiated when explosives are detected at a concentration above the reporting limit of 0.25 µg/L and/or when perchlorate is detected at a concentration above the method detection limit of 0.35 µg/L in the effluent of the secondary GAC vessels. Section 5.1.2 presents additional parameters that will be monitored as part of the Pew Road system performance monitoring.

4.0 REMEDIAL SYSTEM PERFORMANCE MONITORING

System performance monitoring describes the hydraulic and chemical monitoring program for both Demo 1 RRA ETR systems. These monitoring activities are focused on assessing the system performance with respect to plume capture, hydraulic impact on surface water and changes in contaminant concentrations.

4.1 Hydraulic Monitoring

Hydraulic monitoring will be conducted to assess the effectiveness of the well field on plume capture both horizontally and vertically. Hydraulic monitoring to demonstrate plume capture will include two components. The first is to use a combination of measured groundwater elevation data and analytically derived capture zone estimates to graphically illustrate capture. The second will be to recalibrate the groundwater flow model to simulate observed draw downs in the aquifer under system operation. After the recalibration effort, the model will be used to predict the magnitude of capture for each RRA ETR system.