Final_J-3_Range_RRA_SPEIM_Plan_2006.pdf

Impact Area Groundwater Study Program

FINAL

J-3 Rapid Response Action System Performance and Ecological Impact

Monitoring Plan

Camp Edwards Massachusetts Military Reservation

Cape Cod, Massachusetts

June 21, 2006

Prepared for:

U.S. Army Corps of Engineers New England District

Concord, Massachusetts for

U.S. Army / National Guard Bureau

Camp Edwards, Massachusetts

Prepared by:

ECC

Contract No. DACW33-02-D-0003, CTO 002

IMPACT AREA GROUNDWATER STUDY PROGRAM

FINAL

J-3 Rapid Response Action System

Performance and Ecological Impact Monitoring Plan

Camp Edwards Massachusetts Military Reservation

Cape Cod, Massachusetts

Prepared for:

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

Camp Edwards, Massachusetts

Prepared by:

ECC

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 DACW33-02-D-0003. 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 1 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.

Final J-3 Rapid Response Action System Performance and Ecological Impact Monitoring Plan June 21, 2006

TABLE OF CONTENTS

PAGE

ACRONYMS AND ABBREVIATIONS...............................................................................iv EXECUTIVE SUMMARY ............................................................................................ ES-1

1.0 INTRODUCTION.....................................................................................................1-1

1.1 PURPOSE .......................................................................................................1-2

1.2 ORGANIZATION OF SPEIM PLAN .................................................................1-2

2.0 BACKGROUND ......................................................................................................2-1

2.1 SITE SETTING ................................................................................................2-1

2.1.1 J-3 Range ..............................................................................................2-1

2.1.2 FS-12 .....................................................................................................2-2

2.2 GEOLOGY .......................................................................................................2-3

2.3 HYDROLOGY ..................................................................................................2-4

2.4 J-3 CONTAMINANT DISTRIBUTION ..............................................................2-4

3.0 J-3 SYSTEM DESIGN.............................................................................................3-1

3.1 WELLFIELD DESIGN ......................................................................................3-1

3.2 TREATMENT SYSTEM DESIGN.....................................................................3-2

3.2.1 Treatment System Overview..................................................................3-2

3.2.2 Modeled Influent Characteristics............................................................3-2

3.2.3 Effluent Criteria ......................................................................................3-3

4.0 PERFORMANCE MONITORING............................................................................4-1

4.1 HYDRAULIC MONITORING............................................................................4-1

4.1.1 Baseline Monitoring ...............................................................................4-1

4.1.2 Start-Up Monitoring and Testing ............................................................4-2

4.1.3 Long-Term Hydraulic Monitoring............................................................4-6

4.2 CONTAMINANT MONITORING ......................................................................4-7

4.2.1 Periodic Monitoring ................................................................................4-7

4.2.2 Long-Term Plume Monitoring ..............................................................4-10

4.3 PLANT PERFORMANCE ..............................................................................4-11

5.0 DATA EVALUATION...............................................................................................5-1

5.1 HYDRAULIC DATA..........................................................................................5-1

5.1.1 Baseline Hydraulic Data.........................................................................5-1 i J-3 RRA SPEIM Text

ECC-J23-35AY5302-M22-0009

June 21, 2006

5.1.2 Start-Up Hydraulic Data .........................................................................5-1

5.1.3 Long-Term Hydraulic Data.....................................................................5-3

5.2 CHEMICAL DATA............................................................................................5-3

5.3 PLANT PERFORMANCE ................................................................................5-5

6.0 ECOLOGICAL IMPACT MONITORING..................................................................6-1

7.0 MONITORING AND REPORTING SUMMARY ......................................................7-1

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

FIGURES

Figure 1-1 Location of J-3 Range Study Areas

Figure 2-1 J-3 Range Features

Figure 2-2 Location of J-3 and FS-12 Plumes

Figure 2-3 Regional Surficial Geology Map of Upper Cape Cod

Figure 2-4 2000 Synoptic Groundwater Elevations

Figure 3-1 J-3 Plume RRA IX-GAC-GAC Process Flow Diagram

Figure 4-1 Baseline and Start-Up Hydraulic Monitoring Locations J-3 SPEIM

Figure 4-2 Long-Term Hydraulic Monitoring Locations J-3 SPEIM

Figure 4-3 Chemical Monitoring Locations J-3 SPEIM

Figure 4-4 Source Area Particle Tracks of the J-3 Plume (with 1-year time markers) Ambient Conditions

Figure 4-5 Reverse Particle Tracks from J-3 Extraction Wells (with 1-year time markers) under Operational Conditions

Figure 4-6 J-3 Plant Sampling Locations

Figure 6-1 Drawdown and Mounding for Snake Pond and J-3 Wetland under J-3 System Operational Conditions

TABLES

Table 4-1 Start-Up and Baseline Hydraulic Monitoring Wells for the J-3 System

Table 4-2 Start-Up Test Procedures for the J-3 System

Table 4-3 Long-Term Hydraulic Monitoring Wells for J-3 SPEIM

Table 4-4 J-3 Groundwater Chemical Monitoring Network

Table 4-5 J-3 System Sampling Locations and Parameters for Operational Monitoring ii

June 21, 2006

APPENDICES

Appendix A Groundwater Monitoring Network and Sampling Frequency Optimization

Appendix B Cross Sections and Sampling Locations for J-3 SPEIM iii

June 21, 2006

ACRONYMS AND ABBREVIATIONS

3-D three-dimensional

AMEC AMEC Earth and Environmental, Inc.

ANG U.S. Air National Guard

ANOVA analysis of variance

AO Administrative Order

AVGAS aviation gas

BBM Buzzards Bay Moraine

BTEX benzene, toluene, ethylbenzene, and xylenes

CERCLA Comprehensive Environmental Response, Compensation and Liability Act of 1980 (Superfund)

CMR Commonwealth of Massachusetts Regulation

COC contaminant of concern

DoD Department of Defense

DO dissolved oxygen

EDB ethylene dibromide

EPA U.S. Environmental Protection Agency

ETR extraction, treatment, and reinjection

FS-12 Fuel Spill-12

GAC granular activated carbon gpm gallons per minute

HMX octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine

IAGWSP Impact Area Groundwater Study Program in inch

IRP Installation Restoration Program

IX ion exchange

JP-4 jet fuel-4

MassDEP Massachusetts Department of Environmental Protection

MCL maximum contaminant level mm millimeter

MMCL Massachusetts maximum contaminant level

MMR Massachusetts Military Reservation

MPP Mashpee Pitted Plain iv

June 21, 2006

ORP oxidation-reduction potential

OU operable unit

PEP pyrotechnic, explosives and propellant

RDX hexahydro-1,3,5-trinitro-1,3,5-triazine

Rf retardation factor

RRA rapid response action

SDWA Safe Drinking Water Act of 1974

SE Southeast

SM Sandwich Moraine

SPEIM system performance and ecological impact monitoring

TERC Total Environmental Restoration Contract

TOC total organic carbon

TSS total suspended solids

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

ZOC zone of contribution µg/L micrograms per liter v

(intentionally blank) vi

June 21, 2006

EXECUTIVE SUMMARY

This System Performance and Ecological Impact Monitoring (SPEIM) Plan outlines the approach to monitoring the effectiveness of the Rapid Response Action (RRA) for the J-3

Range contaminant plume. The RRA for the J-3 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 the J-3 Range at Camp Edwards.

The J-3 Range is one of the ranges formerly utilized by military contractors for testing and development of various weapons and systems, and by the military for training purposes.

The J-3 Range was originally developed between 1935 and 1941 along the west side of

Greenway Road under the designation of the H Range. The H Range was used into the

1950s as a mortar range. In 1968, the area was developed as a test range, under the designation J-3 Range where tactical weapon systems were tested. Beginning in 1979, the

Melt/Pour building was used for the melting and pouring of explosives into test munitions.

The majority of activity at the range included loading, assembly, and explosive testing of tactical ordnance items. Other activities that were reported to have occurred on the range include burning of excess propellant and other explosive debris, disposal of process wastewater generated from milling of explosives at the J-3 Range Melt/Pour building area, release of wastewater (which may have contained explosives, metals and other contaminants) to subsurface drywells and leaching structures, and disposal of various items including spent munitions. Based on the presence of pyrotechnic, explosives and propellant

(PEP) compounds in soils, and particle backtracking of downgradient groundwater contamination, the J-3 Artillery Range/Demolition Area and the Melt Pour Building are the most likely sources for the J-3 plume. Analytical results indicate that the plume which emanates from the J-3 Range Artillery Range/Disposal Area and Melt/Pour Building is composed principally of perchlorate, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX).

The current conceptualized downgradient extent of perchlorate contamination is approximately 3,700 feet from the source area, whereas monitoring data indicate that RDX extends at least 4,500 feet downgradient. The toe of the plume extends an unknown

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June 21, 2006 distance beneath Snake Pond, so the total plume length has not been determined. Based on perchlorate and RDX concentrations in groundwater, the plume has a maximum east-west width of approximately 1,200 feet and a maximum thickness of approximately 90 feet.

Although the J-3 plume contains HMX, the plume extent is largely defined by the distribution of RDX and perchlorate contamination. Also, groundwater concentrations of HMX in the J-3 plume are much lower than the health advisory level [400 micrograms per liter (µg/L)] and are contained within the footprint of the RDX and perchlorate plumes. The maximum concentrations of RDX, HMX, and perchlorate in the plume are 35 µg/L, 100 µg/L and 770 µg/L, respectively.

Other explosives that have been detected in groundwater within the bounds of the J-3 plume include 1,3,5-trinitrobenzene, 2,4,6-trinitrotoluene (TNT), 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, and picric acid. Concentrations of TNT in one well have exceeded the Health Advisory of 2 µg/L in the J-3 plume.

The J-3 RRA system includes two new extraction wells: an in-plume well (J3EWIP1) located northwest of Greenway Road (near monitoring well MW-343) and a well located approximately 200 feet northwest of 90EW0001 (J3EW0032) in combination with existing well 90EW0001. The final wellfield design has a flow rate of 65 gallons per minute (gpm) for the well northwest of 90EW0001 (J3EW0032), 60 gpm for the in-plume well (J3EWIP1), and

50 gpm at existing well 90EW0001 (total of 175 gpm). All water treated from the J-3 RRA system will be reinjected to the aquifer using reinjection wells currently in use for the Fuel

Spill-12 (FS-12) extraction, treatment, and reinjection (ETR) system.

The J-3 RRA treatment option is granular activated carbon (GAC)-ion exchange (IX)-GAC treatment to address both RDX and perchlorate. This treatment train is comprised of leading parallel GAC vessels used to remove RDX, followed by parallel IX vessels to remove perchlorate, followed by parallel final GAC vessels as a polishing step. The existing

FS-12 treatment plant building located inside the eastern border of the Massachusetts

Military Reservation (MMR), southeast of the J-3 plume, will house the J-3 Range treatment train. The J-3 Range treatment system will be located within the existing FS-12 facility, but separate from the FS-12 treatment process which was designed to remediate the contaminants ethylene dibromide (EDB) and benzene, which originate near Greenway Road

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June 21, 2006 at the site of a pipeline release of aviation gas (AVGAS) and jet fuel-4 (JP-4). The J-3

Range treatment system and the FS-12 ETR system will share backwash and effluent systems. This system was brought on-line in 1997 and treats extracted groundwater using liquid-phase GAC. Treated water is returned to the aquifer through reinjection wells. The

Air Force Center for Environmental Excellence (AFCEE) operates the FS-12 ETR system, which is owned by the Department of Defense (DoD).

The modeling results indicate the final RRA design:

• prevents appreciable plume migration;

• actively addresses the zone of highest RDX and perchlorate contamination;

• captures nearly all of the mass upgradient of the southern extraction wells (nearly 98 percent of the perchlorate and 97.3 percent of the RDX mass);

• captures 94.5 percent of the total perchlorate and 88.2 percent of the total RDX mass (a small portion of the plume is situated downgradient of the extraction wells near the north shore of Snake Pond); and,

• remediates the aquifer in a reasonable timeframe (approximately 20 years).

The purpose of this groundwater RRA SPEIM plan is to outline procedures to monitor the effectiveness of the J-3 system. This will be accomplished through a performance monitoring including: hydraulic monitoring, chemical monitoring and plant performance monitoring. Hydraulic monitoring will be conducted to verify the hydraulic performance of the system in regard to capture zone development, gradient manipulation and plume trajectory. The hydraulic monitoring component will consist of baseline monitoring, system start-up monitoring, and long-term monitoring. A total of 51 monitoring well screens will be measured for the baseline event and 7 monitoring well screens will be measured for background. The start-up monitoring will consist of hydraulic measurements at 51 screens.

Start-up testing will include a step-up single well test at J3EWIP1, and a complete test for the three extraction wells operating concurrently to determine the composite steady state drawdown of the system. The hydraulic monitoring of the start-up test will be used to verify system performance by measuring aquifer response and defining the capture zone of the

J-3 system. Long-term hydraulic monitoring will be performed on at monitoring locations semiannually to assess multi-seasonal trends in groundwater levels and hydraulic gradients.

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Chemical monitoring will focus on the assessment of contaminant distribution and plume migration, and determining if uncaptured portions of the J-3 plume are attenuating at rates consistent with design objectives. Assessment of the adequacy of the spatial network was determined through a multiple lines of evidence approach. Quantitative evaluation of the spatial network was performed using various statistical approaches included cluster analysis and three-dimensional (3-D) kriging. Comparisons of unoptimized versus optimized networks were performed to show that variability of plume shells derived from more dense and less dense networks was minimal. Sensitivity tests were also performed at various concentration cut-off intervals to demonstrate the primary drivers in plume fate and transport. Using all of these lines of evidence, a groundwater monitoring network of 74 monitoring locations (71 monitoring well screens plus three extraction wells) was established. The determination of monitoring well frequency was accomplished using various statistical analyses including a Sen’s trend analysis, analysis of variance (ANOVA) and lessons learned from various SPEIM projects around the MMR. The conclusion was that the most efficient frequency of monitoring was annual for the majority of the network with semiannual sampling of key wells at the edges, plume front, and key high mass zones.

Select wells located far downgradient were proposed for biennial (once every two years).

Treatment plant performance monitoring will be conducted to measure the ability of the J-3

ETR system to remove contaminates from the extracted groundwater and produce effluent that is similar in chemistry to that of the aquifer. Monitoring at the treatment system will include influent and effluent sampling to confirm that the treated water being discharged from the plant is below the method detection limit of 0.35 µg/L for perchlorate and the reporting limit of 0.25 µg/L for RDX.

The results of these hydraulic, chemical and plant performance analyses will be presented in an annual report.

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1.0 INTRODUCTION

This System Performance and Ecological Impact Monitoring (SPEIM) Plan for the Rapid

Response Action (RRA) for the J-3 Range plume presents a program for monitoring the effectiveness of the remedial extraction, treatment, and reinjection (ETR) system. A detailed description of the J-3 Range RRA system design is contained in the Final J-3 Range

Groundwater Rapid Response Action (RRA) Plan (ECC 2005). A brief description of the

ETR system is presented in Section 3.0 of this plan. Monitoring activities will be conducted to determine the extent of capture of the hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and perchlorate plumes. Additional monitoring activities will assess the RRA ETR system’s effectiveness in treating the extracted groundwater prior to recharge back to the aquifer through existing Fuel Spill-12 (FS-12) reinjection wells and assessing potential ecological impacts.

A number of wells were evaluated as part of the J-3 Operable Unit that included additional wells beyond those assessed in the J-3 SPEIM network optimization. These additional wells included many outside of the known plume boundaries that would be considered too far afield to be useful in monitoring the migration of plume contaminants in the J-3 plume or for evaluating the performance of the J-3 RRA system. Many of these wells were part of an

Impact Area-wide long-term monitoring program and have been sampled at least three times for a full suite of analyses. Although they may not be in an optimal geographical location to be included in the J-3 SPEIM network, they have been sufficiently characterized to support the upcoming Remedial Investigation (RI) for the J-3 groundwater plume.

The J-3 Range is located adjacent to and southeast of the Impact Area, and is the southernmost of the four former training ranges that comprise the Southeast (SE) Ranges

(Figure 1-1). The SE Ranges are former military training and defense contractor test ranges that operated from the mid 1930s through the early 1990s; the past activities have resulted in explosives and perchlorate contamination in the groundwater.

The work was performed in accordance with the provisions of AO1 and AO3 including consideration of the substantive clean up standards of the Massachusetts Contingency Plan

(MCP) 310 CMR 40.

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1.1 PURPOSE

The installation of the RRA ETR system will facilitate contaminant mass removal and control plume migration. By controlling the spread of the plume, the RRA ETR system will limit the ultimate size of the comprehensive remedy and associated effects on natural resources.

The purpose of this SPEIM plan is to specify monitoring activities to meet the following objectives:

• evaluate hydraulic conditions to assess the effectiveness of the RRA ETR system on the contaminant plume;

• evaluate the RRA ETR system’s impact on ecological receptors, specifically, the effect on groundwater elevations at Snake Pond and the J-3 wetland;

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

• assess the treatment system’s performance at removing RDX and perchlorate from groundwater prior to recharge back to the aquifer through reinjection wells; and,

• assess changes in general groundwater chemistry throughout the treatment process.

The RRA ETR system is expected to operate from September 2006 through spring 2008.

The final comprehensive remedy for the J-3 plume will be assessed following completion of the groundwater characterization report and feasibility study. The RRA ETR system will remain operational until a remedy has been selected and implemented.

1.2 ORGANIZATION OF SPEIM PLAN

The site setting, geology, hydrology, and contaminant distribution are presented in Section

2.0. A general description of the J-3 RRA ETR system is presented in Section 3.0. The approach for hydraulic and chemical monitoring of the treatment system is presented in

Section 4.0. The methods of data evaluation for the hydraulic and chemical data collected from the well network and treatment plant are presented in Section 5.0. An assessment of potential impacts to ecological receptors is presented in Section 6.0. The monitoring and reporting schedule is presented in Section 7.0. References used in this plan are presented

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June 21, 2006 in Section 8.0. A temporal and spatial optimization assessment conducted to determine the most efficient monitoring network is presented in Appendix A. Cross sections for the RDX and perchlorate plumes with associated sampling frequencies are presented in Appendix B.

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June 21, 2006

2.0 BACKGROUND

The site setting, geological and hydrogeological setting, and contaminant distribution for the

J-3 Range plume are summarized in this section.

2.1 SITE SETTING

The Massachusetts Military Reservation (MMR) is located in the western portion of Cape

Cod and occupies approximately 22,000 acres (34 square miles) within the towns of Bourne, Sandwich, Mashpee, and Falmouth in Barnstable County, Massachusetts. Military use of portions of the MMR began as early as 1911. Most of the activity, however, has been conducted since 1935 and has included operations by the U.S. Army, U.S. Coast Guard, U.S. Air Force, Massachusetts Army National Guard, U.S. Air National Guard (ANG), and

Veterans Administration. The level of activity at MMR has varied over its operational history.

2.1.1 J-3 Range

The J-3 Range (Figure 2-1) is located adjacent to and southeast of the Impact Area, and is one of the ranges formerly utilized by military contractors for testing and development of various weapons and systems, and by the military for training purposes. The J-3 Range was originally developed between 1935 and 1941 along the west side of Greenway Road under the designation of the H Range. It is approximately 600 feet wide by 3,200 feet long, with the long axis oriented northwest-southeast. The range reportedly contained two firing points at which 60 millimeter (mm), 81 mm, and 3-inch (in) Stokes mortars were fired toward targets in the Impact Area. The H Range was used into the 1950s as a mortar range. In

1968, the area was developed as a test range, under the designation J-3 Range. AVCO used the J-3 Range beginning in 1970 to develop and test tactical weapon systems for the

U.S. Army and U.S. Air Force. Beginning in 1979, the Melt/Pour building was used for the melting and pouring of explosives into test munitions. The majority of activity at the range included loading, assembly, and explosive testing of tactical ordnance items. Other known activities included warhead deployment techniques, such as parachute drop, launcher deployment, and on-board sensor evaluation. Reportedly, warheads up to 100 pounds were tested at the J-3 Range (AMEC Earth and Environmental, Inc. [AMEC 2001]). In addition, 2-1

June 21, 2006 the following activities are reported to have occurred on the range: burning of excess propellant and other explosive debris; disposal of process wastewater generated from milling of explosives at the J-3 Range Melt/Pour building area; release of wastewater (which may have contained explosives, metals and other contaminants) to subsurface drywells and leaching structures; and disposal of various items, including spent munitions. Some of the munitions tested and/or found at the J-3 Range included 20 mm rounds, 30 mm rounds, 8-in rounds, M-159 signal flares, 40 mm grenades, 81 mm mortar rounds, 60 mm rounds, 2.36-in, 3.5-in and 4.5-in barrage rockets.

The J-3 Range and immediate downgradient areas are located within the Mashpee Pitted

Plain (MPP), which consists of high-permeability sand and gravel, with intermittent lenses of fine sands and silts. The Impact Area is proximal to the apparent glacier terminus, and therefore, contains the coarsest sand and gravel deposits in the MPP (Masterson et al.

1997). The J-3 Range lies near the top of the Sagamore Lens of the aquifer underlying the upper Cape, and as a result, the water table beneath the range is very flat. This results in low horizontal gradients and relatively steep vertical gradients. Additional information regarding source area characterization efforts are presented in the Final J-3 Range

Supplemental Soil Workplan (AMEC 2004).

2.1.2 FS-12

The FS-12 plume is situated immediately southeast of the J-3 plume (Figure 2-2). It is unrelated to the J-3 Range; however, portions of the existing FS-12 ETR infrastructure will be used during the J-3 groundwater RRA. Accordingly, a brief discussion of the plume is provided below and further discussion is included in subsequent appropriate sections of this

SPEIM plan.

As a result of earlier discovery, the conceptual model of the FS-12 plume and source area has been developed and refined for many more years than the J-3 plume. The FS-12 plume is primarily defined by exceedances of the Massachusetts Maximum Contaminant Levels

(MMCL) for ethylene dibromide (EDB) and the federal maximum contaminant level (MCL) for benzene. EDB and benzene, toluene, ethylbenzene, and xylenes (BTEX) groundwater contamination was a result of a fuel pipeline break and persists within the groundwater over

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30 years after the original spill. The primary contaminants of concern (COCs) in the FS-12 plume are EDB, benzene, toluene and xylenes and these contaminants define the plume boundaries. The benzene, toluene, and xylenes footprints generally lie within the EDB footprint. The origin of the FS-12 plume was a leak of approximately 70,000 gallons from a section of fuel pipeline near Greenway Road on the MMR. Both aviation gas (AVGAS) and jet fuel-4 (JP-4) were carried through the pipeline. The leaking pipeline section was repaired in 1972. A soil vapor extraction system was utilized to address the source area soils

(AFCEE 2000), and an ETR system has been in operation treating the groundwater since

1997 (AFCEE 2004). The most recent description of the FS-12 plume can be found in the

Final Fuel Spill-12 2005 Optimization Technical Memorandum (AFCEE 2005b).

2.2 GEOLOGY

The surficial geology of western Cape Cod comprises glacial sediments deposited during the retreat of the Wisconsinan stage of continental glaciation (Figure 2-3). Three extensive sedimentary units characterize the regional geology: the Buzzards Bay Moraine (BBM), the

Sandwich Moraine (SM), and the MPP. The BBM and the SM lie along the western and northern edges of western Cape Cod, respectively. The BBM and SM are composed of ablation till, which is poorly sorted material ranging from clay to boulder size that was deposited at the leading and lateral edges of two lobes of the Laurentide ice sheet during a readvance of the ice front. These moraines form hummocky ridges. The MPP, which consists of fine to coarse-grained sands forming a broad outwash plain, lies south and east of the two moraines. Underlying the MPP are fine-grained, glaciolacustrine sediments and basal till. In some areas these units are not evident and the sand of the MPP overlies bedrock.

The J-3 plume is migrating through very transmissive unconfined sandy glacial outwash deposits. The sandy nature of the surface soils promote rapid infiltration with little run-off.

There are silty deposits in the lower section of the unconsolidated sediment profile at J-3 where hydraulic conductivities are lower, groundwater velocities are reduced and some plume contaminants are restrained. In the vicinity of J-3, it appears the silt units are interbedded with sands; however, the silts do not directly overlie bedrock. South of the J-3 area, the silty lacustrine deposits overlie the granodiorite bedrock.

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2.3 HYDROLOGY

A single groundwater flow system underlies western Cape Cod, including MMR. The aquifer system is unconfined (i.e., it is in equilibrium with atmospheric pressure and is recharged by infiltration from precipitation). The high point of the water table occurs as a groundwater mound beneath the southeastern portion of Camp Edwards, immediately north of the J-3 plume source area (Figure 2-4). Groundwater flow generally radiates outward from this mound. 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.

The Bass River in Yarmouth (Figure 2-3) forms the eastern lateral aquifer boundary.

As documented in the J-3 RRA, based on water table measurements and contaminant data, a distinct vertical gradient is distinguishable at wells immediately downgradient of the demolition area in the J-3 Range. This indicates notable downward flow near the top of the groundwater mound. Farther downgradient toward the midpoint of the plume, the vertical gradient flattens out, and where the plume approaches Snake Pond there is a clear upward gradient. Based on available hydraulic and chemical data, the vertical gradients near the toe of the plume (adjacent and probably intersecting with the northern portion of Snake

Pond) become more complex (ECC 2005).

Snake Pond, located south of the J-3 ETR system, and the J-3 wetland, located south of the

MMR boundary, north of Snake Pond and east of the northernmost extraction well of the J-3

ETR system, are the only surface water bodies in close proximity to the RRA systems to warrant monitoring for potential ecological impacts due to hydraulic effects. This is further discussed in Section 6.0.

2.4 J-3 CONTAMINANT DISTRIBUTION

COCs as defined in Comprehensive Environmental Response, Compensation and Liability

Act of 1980 (CERCLA) have not been formally agreed upon for the J-3 plume. However, as documented in the J-3 RRA, a risk screening evaluation was conducted to help identify the contaminants to be addressed. The risk screening was conducted using data available at the time that the Draft J-3 Groundwater RRA Plan was developed. The results of the risk

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June 21, 2006 screening support the need for remedial action and indicate that an RRA to address contaminated groundwater will safeguard beneficial use of the aquifer. Based on the risk screening, perchlorate and RDX were used as the primary constituents for modeling, treatability assessment, and system design considerations. A full characterization of groundwater and determination of associated risk will be provided in a future J-3 Range

Groundwater Characterization Report.

The current conceptualized downgradient extent of perchlorate contamination is approximately 3,700 feet from the source area, whereas monitoring data indicate that RDX extends approximately 4,500 feet downgradient (Figure 2-2). It is assumed that groundwater contamination extends beneath the pond, so the actual plume length is not completely known. Based on perchlorate and RDX concentrations in available groundwater data, the plume has a maximum east-west width of approximately 1,200 feet and a maximum thickness of approximately 90 feet.

Although the J-3 plume contains octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), the plume extent is largely defined by the distribution of RDX and perchlorate contamination.

Also, groundwater concentrations of HMX in the J-3 plume are much lower than the health advisory level [400 micrograms per liter (µg/L)] and are contained within the footprint of the

RDX and perchlorate plumes. Hence, the J-3 plume conceptual model focuses on the nature and extent of RDX and perchlorate contamination. The maximum concentrations of

RDX, HMX and perchlorate in the plume are 35 µg/L, 100 µg/L and 770 µg/L, respectively.

Other explosives that have been detected in groundwater within the bounds of the J-3 plume include 1,3,5-trinitrobenzene, 2,4,6-trinitrotoluene (TNT), 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, and picric acid. Concentrations of TNT in one well have exceeded the Health Advisory of 2 µg/L in the J-3 plume.

The general mapped distribution of contaminants from the source area to Snake Pond aligns with the general groundwater flow direction (roughly north-south), displaying a subtle curvature toward the west near the center of the plume and a more easterly curvature as the plume approaches Snake Pond (Figure 2-4). Fate and transport modeling suggests that a

35 to 40-year travel time is necessary to develop the plume from the inferred source area to

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June 21, 2006 its current mapped distribution near the north side of Snake Pond. This prediction is consistent with a calculated average linear groundwater velocity of 0.31 feet per day across the length of the J-3 plume. Because of the low retardation factors (Rfs) for perchlorate (Rf

= 1.0) and RDX (Rf = 1.05), these contaminants travel at or near the velocity of groundwater. Recharge accretion has produced a downward slope of contamination downgradient from the source area. Approximately 1,700 feet downgradient, the plume levels off to a more horizontal trajectory for several hundred feet. Section 4.0 provides more details of the plume’s vertical distribution and internal concentration gradients, and a series of plume cross-sections are provided in Appendix A.

The pattern of contamination near Snake Pond is generally consistent with a converging flow field as groundwater discharges to the pond. Monitoring data for RDX and perchlorate, groundwater head data, and groundwater modeling results indicate an upward flow trajectory beneath the northern bay and northern portion of the main basin of Snake Pond.

Screening data from a borehole (MW-171) on Snake Island (the isthmus on the northern portion of Snake Pond; Figure 2-2), push-boring samples from the U.S. Geological Survey

(USGS) (November 2003), sporadic detections of perchlorate in pond drivepoints (a total of two detects out of 17 drivepoint samples; USGS 2003), and modeling of pond aquifer characteristics, indicate that at least a portion of the plume may be discharging to the pond just south of the island. However, to date, no RDX or perchlorate has been detected in groundwater or surface water downgradient of the pond. A drive point sampling program is planned for the area immediately south of Snake Pond and will provide additional data on potential plume underflow of the pond. The drive points are planned to be installed in the fall of 2005 (IAGWSP 2005).

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3.0 J-3 SYSTEM DESIGN

With input from the EPA and Massachusetts Department of Environmental Protection

(MassDEP), extraction, treatment and reinjection was selected as the remediation approach for the J-3 plume RRA because of its effectiveness and compatibilities with likely future comprehensive response actions. The following sections present a synopsis of the J-3

Range ETR well field design and treatment system design as presented in the J-3 Range

RRA; further discussion on the ETR system is presented in the J-3 Range RRA (ECC 2005).

3.1 WELLFIELD DESIGN

The SE Ranges flow and transport model and three-dimensional (3-D) plume shells for RDX and perchlorate were updated based on comments received by the regulators on the Draft

J-3 Range RRA plan and recent data. Transport simulations were conducted to evaluate the model-predicted trajectory of the J-3 RDX and perchlorate and to determine an appropriate wellfield strategy to capture the J-3 plume. Use of existing FS-12 wellfield and treatment facility infrastructure was considered in developing the final wellfield and treatment train design. Potential impacts to the FS-12 remedial system, specifically mass removal performance and long-term cleanup of the EDB plume, and potential impacts on ecological adherence were also evaluated.

The J-3 capture scenario testing results and constructability review indicated that the most appropriate wellfield design includes two new extraction wells: an in-plume well (J3EWIP1) located northwest of Greenway Road (near monitoring well MW-343) and a well located approximately 200 feet northwest of 90EW0001 (J3EW0032) in combination with existing well 90EW0001. The final wellfield design has a flow rate of 65 gallons per minute (gpm) for the well northwest of 90EW0001 (J3EW0032), 60 gpm for the in-plume well (J3EWIP1), and

50 gpm at existing well 90EW0001 (total of 175 gpm).

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3.2 TREATMENT SYSTEM DESIGN

The following sections include discussion of the J-3 Range ETR treatment system design, including an overview of the treatment system operation, modeled influent concentrations, and effluent criteria.

3.2.1 Treatment System Overview

After reviewing the available information, performing a relative capital cost comparison, and coordination with the Air Force Center for Environmental Excellence (AFCEE) on the design concept, the optimum treatment option was determined to be ion exchange (IX)-granular activated carbon (GAC) treatment (ECC 2005). This treatment train is comprised of parallel

IX vessels to remove perchlorate, followed by parallel leading GAC vessels used to remove

RDX followed by parallel final GAC vessels as a polishing step (Figure 3-1). The J-3 Range treatment system will be located within the existing FS-12 facility, but separate from the FS-

12 treatment process. Although the treatment system will share the FS-12 backwash equipment and effluent system, there is no anticipated impact to the FS-12 extraction and treatment systems from the J-3 system. The J-3 RRA IX and GAC vessels will be used in conjunction with additional system components as summarized in the process flow diagram

(Figure 3-1).

3.2.2 Modeled Influent Characteristics

As documented in the J-3 RRA (ECC 2005), based on the preliminary wellfield scenario testing, the maximum influent concentration of perchlorate from the three extraction wells is expected to approach 4.3 µg/L, with the maximum from any one extraction well approaching

11.7 µg/L. Although the maximum detected perchlorate concentration within the plume is much higher (770 µg/L), influent concentrations in extraction wells are typically much lower because the extraction wells are screened across both low and high concentration areas within plumes and the well captures low concentration areas outside the core of the plume.

They inevitably capture some clean water that mixes with higher concentration water from discreet intervals along the extraction screen.

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The maximum influent concentration of RDX from the three extraction wells is expected to approach 3.9 µg/L, with the maximum from any one extraction well approaching 9.0 µg/L.

The maximum detected RDX concentration within the plume is higher (35 µg/L).

3.2.3 Effluent Criteria

The treated groundwater (effluent) from the J-3 plume treatment system will be combined with the FS-12 effluent and returned to the aquifer via the existing FS-12 reinjection well network.

For the J-3 plume treatment system, the Massachusetts groundwater discharge regulations under 314 Commonwealth of Massachusetts Regulation (CMR) 5.00 et. seq. govern the discharge of treated groundwater and require, in 314 CMR 5.10(3), that the concentrations of discharge effluent be adequate to assure the attainment and maintenance of the assigned groundwater quality standards of the receiving waters, as listed in 314 CMR 6.00 et seq.

The minimum standards for Class I groundwater (MassDEP has classified MMR groundwater as Class I), as listed in 314 CMR 6.07(3), are equivalent to the SDWA MCLs.

The treated effluent will meet these levels prior to discharge to the groundwater. Section 4.3 presents additional parameters that will be monitored as part of the J-3 system performance monitoring.

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4.0 PERFORMANCE MONITORING

This section describes hydraulic, chemical, and plant monitoring intended to support an evaluation of the performance of the J-3 plumes remedial systems. The goals of the SPEIM are to collect the data required to evaluate the effectiveness, performance, and optimization of the remedial system, monitor potential ecological impacts associated with the operation of the remedial system, and assure protection of human health. The monitoring network optimization presented in Appendix A was used in the development of the chemical monitoring network. The hydraulic network was developed based on groundwater flow modeling of system operating stresses and past experiences of system start-up at MMR.

4.1 HYDRAULIC MONITORING

Hydraulic monitoring is conducted to verify the hydraulic performance of the system in regard to capture zone development, gradient manipulation and plume trajectory; assess effects due to changes in system operations or due to external hydraulic stresses; assess potential impacts on adjacent plumes; determine if drawdown is impacting local surface water environments; provide a basis for groundwater flow model refinement and/or recalibration; and to refine and optimize system operation. System flow rates are also monitored to confirm that design flows are being achieved and to provide a further basis for predictive assessment of the rates of mass removal and hydraulic effectiveness.

The hydraulic monitoring of the J-3 remedial system components will include baseline monitoring, start-up monitoring and testing, and long-term periodic monitoring.

4.1.1 Baseline Monitoring

Baseline monitoring refers to an initial monitoring event that is intended to characterize ambient hydraulic conditions prior to the propagation of hydraulic stress from groundwater extraction at the J-3 area by collecting water levels from monitoring wells. Baseline monitoring is proposed at the 51 locations that will be monitored for the start-up test

(including three extraction wells, one piezometer and seven background locations). Table

4-1 provides a listing of baseline monitoring locations.

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Baseline monitoring will be conducted before the remedial system hydraulic start-up test and will continue until after system initial trial operations are complete. The system initial trial operations are intended to test system operations as compared to design requirements and are generally conducted by the system construction contractor.

Baseline monitoring will be conducted before the remedial system hydraulic start-up test and will continue until after system initial trial operations are complete. The system initial trial operations are intended to test system operations as compared to design requirements and are generally conducted by the system construction contractor. The hydraulic start-up test will be conducted after operational shakedown of the treatment system has been completed and trial operations are complete.

Since the J-3 remedial system is located adjacent to the FS-12 system, it is also required that the FS-12 system will be operated in a steady and constant manner during the baseline monitoring and subsequent start-up test. Start-up operations will be coordinated with

AFCEE. In addition, FS-12 operating flow rates prior to and during the start-up activities will be obtained from AFCEE for consideration in assessing aquifer response to J-3 pumping.

4.1.2 Start-Up Monitoring and Testing

Start-up monitoring and testing will be conducted to obtain information that can be used to improve the understanding of aquifer properties and to evaluate the response of the aquifer to hydraulic stresses imposed by the J-3 remedial system. The water level monitoring methods will include continuous monitoring using a transducer/datalogger and periodic monitoring using tape measurement. Background monitoring will also be conducted. In addition to water levels, flow rates at the extraction wells will also be recorded.

The primary objectives of the start-up test are to:

1. Record changes in water levels in monitoring wells and shallow piezometer during start-up of the remedial system.

2. Quantify aquifer response to the pumping stresses and delineate the 3-D hydraulic zones of influence for the extraction wells.

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3. Characterize and refine aquifer properties.

4. Validate model predicted stress and quantify system capture zone development.

5. Provide data to develop a more representative groundwater model to support system optimization.

The zone of hydraulic influence is the area affected by system stress relative to the ambient

(natural/no stress) condition. It is defined as the zone of drawdown at the water table or at depths where change in potentiometric head from ambient conditions occurs. The zone of influence is not the same as the zone of contribution (ZOC) to a well. ZOC is determined by flownet analysis or a particle tracking analysis by subjecting a flow model to a stressed

(operational) condition. The ZOC is usually narrower across the natural flow path than the zone of influence in a regional flow regime, but usually extends further in the upgradient direction.

The data needed to define the zone of influence include water level measurements – before start-up (ambient/unstressed condition) and after start-up (stressed condition). Interval measurements collected during start-up provide useful information to monitor the development of the zone of influence. The development and final shape of the zone of influence provides some insights regarding aquifer heterogeneity. The aquifer characteristics that can be determined with start-up water level monitoring include transmissivity, storativity, and anisotropy. These hydraulic properties (along with the geologic information gathered from well drilling activities during system installation) will be compared to the current site specific geologic and hydrogeologic model in terms of aquifer matrix, sediment properties, and hydrogeologic unit distribution patterns.

The design of the start-up test and monitoring sequence is based on the layout of the wellfield, design goals regarding the propagation of hydraulic stress, and experience from start-up monitoring and aquifer testing previously conducted at the MMR and Impact area.

Similar designs have been successfully used to quantify capture performance at more than

10 system start-up, and shut-down/start-up tests conducted on AFCEE-MMR remedial systems.

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A three phased approach is selected for the start-up test and monitoring for the J-3 extraction system. The first phase is to conduct a single well pumping test at the new in-plume extraction well (J3EWIP1) since the well is the primary well for mass removal and there has been no aquifer testing in this area. The second phase is to conduct a full system test to determine the development of the zone of influence. This approach offers the best combination of data collection and efficiency while achieving the desirable objectives for the system start-up test. Table 4-2 presents the details of the start-up test procedures.

To enhance the data collection for the Phase I aquifer test, one well cluster near the in-plume extraction well is proposed to be installed. The new well will be located approximately 100 feet south of the J3EWIP1 extraction well along the access road from

Greenway Road to well MW-343 (Figure 4-1). The new monitoring well will consist of three well screen intervals that are above, within, and below the extraction interval for the in-plume extraction well (Table 4-1). To determine the potential ecological impact on the wetland from the J-3 extraction system, one shallow piezometer near the J-3 wetland will also be installed. These new wells will also be used to support baseline and long-term monitoring. The proposed monitoring well cluster and piezometer will be installed and developed in accordance with technical procedures as outlined in the Final Generic Quality

Assurance Project Plan (AMEC 2005c).

A narrative summary of the start-up testing sequence is as follows:

• Phase 0 shutdown of trial operation and baseline monitoring - After wellfield trial operations (system checking and verification) are completed, the aquifer will be allowed to return to ambient conditions. A period of 6 days is provided to ensure full recovery to an ambient (unstressed) condition (Table 4-2). The first baseline monitoring event will commence on day 6 after shutdown of trial operations. The baseline monitoring includes continuous water level monitoring using dataloggers and daily manual tape measurements.