J-3_Range_Decision_Document_2015_.pdf

United States Environmental Protection Agency

Region 1

Decision Document

J-3 Range Operable Unit

Camp Edwards

Joint Base Cape Cod

Cape Cod, Massachusetts

TABLE OF CONTENTS PAGE

PART I: DECLARATION FOR THE SDWA DECISION DOCUMENT

A. SITE NAME

B. STATEMENT OF BASIS AND PURPOSE

C. ASSESSMENT OF THE SITE

D. DESCRIPTION OF RESPONSE ACTIONS

E. DETERMINATIONS

F. SUPPORTING DATA

G. AUTHORIZING SIGNATURE

PART II: THE DECISION SUMMARY

A. SITE DESCRIPTION

B. SITE HISTORY AND ENFORCEMENT ACTIVITIES

1. HISTORY OF SITE ACTIVITIES

2. HISTORY OF INVESTIGATIONS AND RESPONSE ACTIONS

3. HISTORY OF RELEVANT FEDERAL AND STATE ENFORCEMENT ACTIVITIES

C. COMMUNITY PARTICIPATION

D. SCOPE AND ROLE OF OPERABLE UNITS

E. SITE CHARACTERISTICS

F. CURRENT AND POTENTIAL FUTURE SITE AND RESOURCE USES

G. SUMMARY OF SITE RISKS

H. RESPONSE ACTION OBJECTIVES FOR GROUNDWATER

I. DEVELOPMENT OF ALTERNATIVES FOR GROUNDWATER

J. DESCRIPTION OF ALTERNATIVES, SUMMARY OF COMPARATIVE ANALYSIS

AND THE SELECTED RESPONSE ACTION

K. RESPONSE ACTION IMPLEMENTATION

L. DETERMINATIONS

M. DOCUMENTATION OF NO SIGNIFICANT CHANGES

N. STATE ROLE

PART III: THE RESPONSIVENESS SUMMARY

List of Figures

Figure 1: J-3 Range Location Map

Figure 2: J-3 Range Layout

Figure 3: J-3 Range Study Areas

Figure 4: J-3 Range Area 1 Excavated Areas

Figure 5: J-3 Range Area 3 Excavated Areas

Figure 6: J-3 Range Extraction Well Locations and Pipelines

Figure 7: J-3 Range Land Use Control Area

List of Tables

Table 1: Summary of Alternatives

Table 2: Summary of Regulatory Considerations

List of Appendices

A: Massachusetts Department of Environmental Protection Letter of Concurrence

B: Glossary of Terms and Acronyms

C: Index of Key Supporting Documents

D: Soil and Groundwater Screening

E. Work Plan Project Notes

PART I: DECLARATION FOR THE SAFE DRINKING WATER ACT DECISION DOCUMENT

A. SITE NAME

The subject site is the J-3 Range (also referred to as “the Site”), which is located at Camp Edwards at the Joint Base Cape Cod (JBCC) (formerly Massachusetts Military Reservation (MMR)).

B. STATEMENT OF BASIS AND PURPOSE

This Decision Document presents the selected response actions for the J-3 Range. The selected response actions were chosen in accordance with Section 1431(a) of the Safe Drinking Water Act

(SDWA), 42 USC § 300i(a), as amended, and the Administrative Order (AO) concerning response actions issued thereunder, U.S. Environmental Protection Agency Region 1 (EPA) Administrative

Order No. SDWA-1-2000-0014 (AO3). The authority to select the necessary response action(s) has been delegated to EPA Region 1’s Regional Administrator pursuant to EPA Delegation No.

9-17 (1200-TN-350) dated May 11, 1994, and further delegated to EPA Region 1’s Director, Office of Site Remediation and Restoration, pursuant to a redelegation of authorities dated April 6, 2010.

This decision is based on the Administrative Record, which has been developed in accordance with AO3 and with a previous EPA Administrative Order, SDWA 1-97-1019 (AO1), including consideration of the substantive cleanup standards of the Massachusetts Contingency Plan

(MCP) 310 CMR 40.0000. The Administrative Record is available for review by appointment at the Army National Guard’s Impact Area Groundwater Study Program (IAGWSP) office, PB0516

West Outer Road, Camp Edwards, MA.

C. ASSESSMENT OF THE SITE

On July 13, 1982, EPA determined that the Cape Cod Aquifer is the sole or principal source of drinking water for Cape Cod, Massachusetts, and that the Cape Cod Aquifer, if contaminated, would create a significant hazard to public health (47 Fed. Reg.30282). Contaminants from the

Training Ranges and Impact Area at JBCC are present in and may enter and migrate in the aquifer. The response actions selected in this Decision Document are necessary to protect the

Cape Cod Aquifer, an underground source of drinking water on which the public relies. The J-3

Range is also located within the Upper Cape Water Supply Reserve established pursuant to

Chapter 47 of the Massachusetts Acts of 2002 and designated as conservation land under the care and control of the Massachusetts Division of Fisheries and Wildlife. The IAGWSP, under the oversight of EPA and the Massachusetts Department of Environmental Protection (MassDEP), has investigated potential soil and groundwater contamination at the site.

D. DESCRIPTION OF COMPREHENSIVE RESPONSE ACTIONS

This Decision Document sets forth the selected response actions taken and to be taken for addressing the source areas contributing to groundwater contamination, and the groundwater contamination at and emanating from the Site. The source areas include both soil contamination and unexploded ordnance (UXO) that may be in or on the soil. There may be additional areas on the Site where UXO and the soil beneath may pose public safety risks (potential presence of munitions and explosives of concern (MEC) which include unexploded ordnance/discarded military munitions/munitions constituents (UXO/DMM/MC)), ecological risks, dermal contact risks, and/or soil ingestion risks. These potential UXO-related risks are not addressed by this Decision

Document, which is being issued pursuant to Administrative Order No. SDWA-1-2000-0014 and

Section 1431(a) of the SDWA, and which focuses on potential endangerment to the health of persons deriving from contaminants present in or likely to enter the underground source of drinking water.

During the investigations of the Site, several response actions were taken to remove the sources of groundwater contamination. Disposal pits containing UXO, and contaminated soil at and in the vicinity of firing points, targets, and areas used for burning and disposal of propellants and explosives at and in the vicinity of the Demolition Area and Melt/Pour building are believed to be the cause of much of the groundwater contamination. It is believed that most of the source areas were identified and removed during the previous investigations. However, there are a few areas on the range that require additional investigation to confirm that potential sources have been completely addressed. Soil contamination and UXO potentially posing a threat to groundwater will be removed. UXO clearance in select areas of the range and confirmatory soil sampling will be conducted as part of the remedy to verify source removal is complete. These areas are primarily located within or near the artillery and warhead firing ranges in the central portion of the range, and include locations where soil and or UXO have been excavated, but the effectiveness of the removal actions have not been completely established.

In addition, UXO remain the Barrage Rocket study area in the northern portion of the J-3 Range.

These remaining items pose a potential long term threat to the groundwater. Soil contamination and UXO potentially posing a threat to groundwater will be removed. Work plans describing the

UXO clearance and confirmatory soil sampling have been approved by EPA, in consultation with

MassDEP (Appendix E). The clearance work will employ techniques to minimize habitat destruction while maximizing the reduction of UXO within the Barrage study area.

Based on groundwater sampling results, EPA, in consultation with MassDEP, deemed it necessary to develop and evaluate a range of potential response actions to address contaminants detected in groundwater associated with the J-3 Range. The Remedial Investigation / Feasibility

Study (RI/FS) for the Site identified Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and perchlorate as the contaminants of concern (COCs) for groundwater.

These groundwater COCs were used to develop and evaluate a range of potential response actions for the Site. The Site contains a large-scale plume of RDX and perchlorate migrating from sources on the J-3 Range. Groundwater modeling was used to determine the feasibility of the alternatives for the plume. The cleanup objectives for the J-3 Range groundwater plume are: to restore the useable groundwater to its beneficial use wherever practicable, within a timeframe that is reasonable given the particular circumstances of the site and to provide a level of protection in the aquifer that takes into account that the Cape Cod Aquifer, including the Sagamore Lens, is a sole source aquifer that is susceptible to contamination; to prevent ingestion and inhalation of groundwater containing the contaminants of concern (COCs) (RDX and perchlorate), in excess of federal maximum contaminant levels (MCLs), Health Advisories (HA), drinking water equivalent levels (DWELs), applicable State standards or an unacceptable excess lifetime cancer risk

(ELCR) or non-cancer Hazard Index (HI); and to prevent groundwater in excess of Health

Advisories, drinking water equivalent levels (DWELs), applicable State standards or an unacceptable excess lifetime cancer risk or non-cancer Hazard Index from migrating past the base boundary located down gradient of Greenway Road on Camp Edwards.

There currently is no federal drinking water standard for perchlorate. However, in December

2008, EPA issued an Interim Drinking Water Health Advisory for exposure to perchlorate in water of 15 micrograms per liter (µg/L). Also, MassDEP promulgated a Massachusetts Maximum

Contaminant Level (MMCL) for perchlorate of 2 µg/L in July 2006.

The lifetime federal Health Advisory for RDX in drinking water is 2 µg/L, the MCP GW-1 standard is 1 µg/L, and the 10-6 ELCR risk-based concentration that results in an increased lifetime cancer risk of one in a million is currently 0.6 µg/L.

The EPA, in consultation with MassDEP, has selected a response action in the J-3 Range groundwater plume under which the aquifer, which has been designated a Sole Source Aquifer by the EPA and a Potentially Productive Aquifer by the MassDEP, will be restored. The groundwater response actions will ensure that the groundwater containing RDX at concentrations greater than the 10-6 risk-based level and/or perchlorate greater than 2 µg/L is restored to protective levels.

The selected response action consisting of Focused Groundwater Extraction, Treatment and

Reinjection with Monitored Natural Attenuation with Land-Use Controls (LUCs), and confirmatory soil sampling and UXO clearance to verify all sources have been addressed provides the best balance of the criteria used to evaluate cleanup alternatives.

The selected response action achieves cleanup goals in a reasonable timeframe and protects human health through the use of groundwater extraction and treatment and groundwater monitoring to ensure that groundwater modeling predictions regarding the reduction and migration of contamination are valid and that contamination levels continue to decline. Human health will be further protected through the implementation and verification of LUCs. These LUCs will prevent use of contaminated portions of the aquifer at the Site for drinking water purposes until groundwater data confirms that contamination has been reduced to below risk-based levels. The

LUCs will also prevent activities that may interfere with the treatment and monitoring systems.

The major components of the source and groundwater response action for the J-3 Range groundwater plume are:

An investigation including soil sampling and removal of additional geophysical anomalies in select additional areas of the range to verify source removal is complete. These areas include the central portion of the J-3 Range and the Barrage Rocket study area. A work plan (J-3 Range Confirmatory Sampling Program Project Note, dated May 2015, and J-3

Range Confirmatory Geophysical Investigation, dated May 2015) describing the soil sampling and geophysical investigations has been approved by EPA, in consultation with

MassDEP, and will be implemented as part of the remedy (Appendix E). Soil contamination and UXO posing a threat to groundwater shall be removed.

Extraction and treatment of groundwater by shifting pumping stress between the three existing and one new extraction well within the current system design and/or expanding the system if necessary to ensure complete containment of the plume at concentrations above cleanup levels up gradient of the base boundary; treatment with granular activated carbon and ion exchange resin at the existing and/or expanded treatment system; and reinjection of the treated water at the existing reinjection wells.

Long-term groundwater monitoring at existing and new monitoring wells to verify the effectiveness of the source response action; to ensure that groundwater modeling predictions regarding the reduction and migration of contamination are valid; and to ensure that any remaining contamination remains below risk-based levels.

Implementation and verification of LUCs to prevent use of contaminated portions of the aquifer for drinking water until contamination is reduced to below risk-based levels and to prevent actions that would interfere with the remedy.

Five year reviews to determine if the groundwater treatment system is still protective and achieving the goals established and to determine if source response actions continue to protect groundwater.

E. DETERMINATIONS

The response actions selected in this Decision Document will protect the public health from any endangerment which may be presented by the presence or potential migration of COCs from the

Site into the underlying Sole Source Aquifer. The response action selected in this Decision

Document, issued pursuant to AO3 and Section 1431 of the SDWA, addresses the unacceptable threats to the groundwater aquifer from the Site. In this Decision Document, EPA is making no determination regarding any remaining public safety risk, ecological risk, dermal contact risk, and/or soil ingestion risk posed by any remaining contamination at the Site.

As required by AO3, the selected alternatives for the Site (Focused Groundwater Extraction, Treatment and Reinjection, Monitored Natural Attenuation, and Land Use Controls for groundwater and confirmatory soil sampling and UXO clearance) provides a level of protection to the aquifer underlying and down gradient of the Site commensurate with the aquifer’s designation as a Sole Source Aquifer and a Potentially Productive Aquifer and is protective of human health.

In addition to annual reports on groundwater monitoring and verification of Land Use Controls, the selected response actions include periodic reviews at frequencies not to exceed five years.

The scope of each review will include, but not be limited to, sampling data, modeling data, and other relevant data. EPA, in consultation with MassDEP, will review this and any other relevant information to determine if additional measures are necessary for the protection of human health.

This will include information acquired after the implementation of the selected response action

(such as new regulatory requirements or changes in the environmental conditions of the Site).

F. SUPPORTING DATA

Detailed information on the Site is included in the Final J-3 Range Remedial Investigation/

Feasibility Study dated September 2014. An overview of the Site, including decision factor(s) that led to selecting the groundwater response action, is included in the Decision Summary section of this document. The Decision Summary section also includes information on RDX and perchlorate, their respective concentrations, the baseline risk, the cleanup levels established and the basis for the levels, current and future land and groundwater use assumptions used in the baseline risk screening and Decision Document, land and groundwater use that will be available at the Site as a result of the selected response action, and decision factor(s) that led to selecting the remedy. Additional information can be found in the Index of Key Supporting Documents, which is Appendix C to the Decision Document.

G. AUTHORIZING SIGNATURE

This Decision Document documents the selected response actions for remediation of the J-3

Range within Camp Edwards at the JBCC. The response actions were selected by EPA under the authority of the SDWA. The MassDEP concurs with this decision.

U.S. Environmental Protection Agency

By: ________________________ Date: ____________________

Nancy Barmakian

Acting Director, Office of Site Remediation and Restoration

Region 1

PART II: THE DECISION SUMMARY

A. SITE DESCRIPTION

The J-3 Range is located on Camp Edwards on the JBCC on Cape Cod in Massachusetts (Figure

1). It is located adjacent to the Impact Area and is the southernmost of four former military training and defense contractor test ranges that collectively operated from the 1930s until the 1990s. The

J-3 Range is approximately 1,280 meters long and between 240- and 490-meters wide. The range is oriented southeast to northwest, with the southeastern “up-range” end near Greenway Road, bordered to the northeast by the L Range and the northwestern “downrange” end extending to

Chadwick Road. Physical features of the J-3 Range fell into four general categories: contractor facilities, contractor test firing ranges, contractor disposal areas, and former military training areas lying adjacent to the J-3 Range proper. Access to the J-3 Range is currently restricted by a locked gate at Greenway Road.

B. SITE HISTORY AND ENFORCEMENT ACTIVITIES

1. History of Site Activities

The J-3 Range was originally established 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 and rocket range. In 1968, the area was developed as the J-3 Range by

AVCO/Textron Systems Corporation (TSC) as a Department of Defense contractor test range, and used into the late 1990s. The primary mission of TSC was to develop and test tactical weapons systems under contract to the U.S. Army and U.S. Air Force. Textron used the following facilities at the range: headquarters trailer; workshop building; explosive loading building

(melt/pour facility); ordnance assembly/X-ray building; instrumentation trailer; environmental test/assembly building; two test towers; four explosives storage bunkers; and several test range areas (Figure 2).

The majority of the activity that occurred at the J-3 Range proper included shaping and loading ordnance, ordnance assembly, and ordnance testing. An on-site melt/pour facility was used for the melting and pouring of raw explosives during the preparation/assembly of various munitions components. The operations included the melt/pour explosive loading, hydraulic press consolidation, explosive machining, and mechanical inspection. Disposal activities conducted at the range consisted of propellant, explosives, and wastewater disposal and waste burning on the ground surface and in burial pits. Other activities included evaluation of warhead deployment techniques, such as parachute drop, launcher deployment, and on-board sensor evaluation.

Ordnance ammunition testing, such as 20mm and other miscellaneous munitions testing

(including warhead testing; vibration, drop and burn tests; hazard classification; and explosive train tests) were also performed at the site.

2. History of Investigations and Response Actions

Investigations were conducted at the J-3 Range between 1997 and 2013 to identify the nature and extent of contamination in soil and groundwater resulting from past military activities. Data collected as part of these investigations were used to characterize the nature and extent of groundwater contamination emanating from the Site, any continuing sources of contamination, including soil contamination and potential future contamination from UXO, and to provide a basis for the evaluation of risk(s) posed by the Site.

During response actions conducted from 2004 to 2008, approximately 2,400 cubic yards of soil contaminated with explosives and perchlorate were excavated from the north-central and south-central portions of the J-3 Range and treated on-site by thermal desorption or disposed of off-site at permitted facilities.

Geophysical investigations were conducted from 1997 through 2013 in several different phases utilizing several approaches to identify and remove UXO. Over the course of these ongoing removal actions, approximately 1,900 UXO containing high explosives (HE) were removed. In addition, approximately 560 UXO containing small quantities of explosives were removed along with 29,600 pounds of range debris.

These targeted removals of soils and UXO have likely removed the majority of items posing as active sources of groundwater contamination. A brief summary of the investigations and response actions performed at the Site is provided below. To simplify the discussion, the range has been divided into six subareas (Areas 1 through 6) (Figure 3). The areas were chosen based on historical range use, range features and the conceptual model of the range. A more detailed discussion can be found in Sections 4 and 5 of the September 2014 Remedial

Investigation/Feasibility Study (RI/FS) report.

Source Investigations and Results

Source characterization investigations on or at the J-3 Range commenced in 1997 with soil and groundwater samples collected at areas identified as having the highest probability of contaminant releases. Initial investigations focused on those features identified during a historical aerial photograph analysis of Camp Edwards. Additional range features were included in the investigation as range records became available. Significant information regarding range activities was also obtained through interviews of current and former base employees and range workers and observations noted during site reconnaissance. Soil samples were collected at specific features noted in site records, aerial photographs and during site reconnaissance, at the locations of geophysical anomalies, before and after blow-in-place (BIP) events, proposed excavation areas, and from the base of excavations after soil removal activities.

During the period from1997 through March 2013, 1,700 soil samples were collected from 505 locations within the J-3 Range investigation area (Figure 3).

Area 1

Area 1 is located in the southernmost portion of the J-3 Range. This area of the range had a

Melt/Pour building and associated features including an above-ground storage tank, a wastewater holding tank, and a septic tank. Results of soil investigations in Area 1 indicated elevated levels of explosives associated with the former melt/pour structure, the septic tank, the wastewater holding tank and a wastewater discharge area. The extent of the groundwater plume is consistent with a source in this location. This area was addressed during soil removal actions, no significant soil contamination remains. Prior to excavation a UXO clearance was conducted within the general limits of the melt/pour facility. No UXO was identified. Munitions items identified during a limited geophysical investigation conducted in the southern portion of Area 1 were small arms ammunition, barrage rockets, and 2.36 inch rockets that are likely related to the military training that took place prior to development of the J-3 Range as a contractor test range. Additional single items containing high explosive (HE) or small quantity energetics could remain at Area 1.

Area 2

Area 2 is located in the southeastern portion of the J-3 Range. Features that are or were formerly located in this subarea included a 20mm/30mm firing range and building, a workshop building including drywells, water wells, and septic tank, and a burn kettle/conex area including a former flammable storage shed. Results of soil investigations and geophysical investigations in Area 2 indicated detections of explosives in select areas. Contaminated soils were removed from two drywells. No munitions items were encountered during the UXO clearance and support activities associated with the two drywells. Three UXO items were encountered during access clearance.

These items could have been the result of errant shots or discarded munitions. It is not likely that significant numbers of additional UXO would be found in this area based on the results of the investigations and known past usage of this portion of the range.

Area 3

Area 3 is located in the south-central portion of the range and included an artillery range and warhead test firing range, demolition area, explosive storage bunkers, and additional features associated with or in the vicinity of these ranges including a minuteman missile shroud test pad, ricochet trough area, giant patriot test area, drum disposal area former flight line firing position and x-ray building, concrete firing points pad and drop tower, former M550 launch house and target walls. Results of soil investigations and geophysical investigations in Area 3 indicated elevated levels of explosives that were addressed during soil removal activities in the artillery/warhead test firing range, demolition area, and drum disposal area. The extent of the groundwater plume is consistent with sources in these locations. Two burial pits and one burn pit located in this area contained the highest percentage of UXO items encountered in Area 3.

Numerous other single UXO items found in this area are attributable to both training and testing activities. It is possible that fragmentation, metallic debris, or individual intact munitions, both inert and HE, remain as isolated occurrences in Area 3.

Area 4

Area 4 is located in the north-central portion of the J-3 Range. Features formerly located here consisted of the ordnance assembly/x-ray building, environmental test/assembly building, gauntlet area, and presumed M550 berm area. The results of soil and geophysical investigations resulted in no detections of explosives compounds, and limited UXO items. It is possible that additional inert bodied 40mm projectiles with live fuzing may remain within the M550 berm area.

Individual mortars may also remain within Area 4 at low frequency.

Area 5

Area 5 is located in the southwestern portion of the J-3 Range along a hillside and was reportedly used as part of a training range and impact area. Results of soil and geophysical investigations in this area identified 3-inch Stokes mortars as well as a few 60mm/81mm mortars as the principal

UXO items. The few UXO items encountered are likely attributable to training. Single UXO items likely remain in Area 5. Low levels of explosives were detected at a few locations.

Area 6

Area 6 is located in the northern portion of the range and was the site of significant training activities using 4.5-inch barrage rockets. Both 60mm and 81mm mortars were found in this area in addition to dozens of barrage rockets. Limited soil contamination was associated with these items. Isolated medium- to small-sized geophysical anomalies still remain on the range representing fragmentation, metallic debris, or individual inert or HE munitions. Items that could remain on the range containing HE or small quantity energetic include 4.5-inch barrage rockets, 81mm mortars, 4.2-inch mortars, and 75mm projectiles. There is also evidence to support that barrage rockets and mortars still remain in uninvestigated areas of Area 6.

Groundwater Investigations and Results

A large-scale plume of comingled RDX and perchlorate contaminated groundwater has been found to be migrating from sources at the J-3 Range. The perchlorate plume, as defined by perchlorate above the MMCL of 2 μg/L, is approximately 3,500-feet long and approximately 450-feet wide (Figure 6).

Through mass removal via the J-3 Range Groundwater Rapid Response Action (RRA) ETR system that was installed in 2006 and natural attenuation, perchlorate concentrations have decreased throughout most of the plume. The location of the historic maximum plume concentration of 770 μg/L (MW-198M3) has decreased most recently to a concentration of 2.7 μg/L. Significant decreases have been observed in areas in proximity to extraction wells.

However, significantly higher perchlorate concentrations are currently observed in the influent to extraction well J3EW1P1 indicating the presence of much higher perchlorate concentrations within the J-3 plume than what is presently being detected by the chemical monitoring network.

Perchlorate concentrations in the source area well have declined from a maximum of 120 ug/L

(June 2005) to 4.5 ug/L in the latest sampling event (July 2013).

Like the perchlorate plume, the RDX release likely originated at the J-3 Demolition Area and/or the Melt/Pour building area of the site. The extent of the RDX plume, as defined by concentrations of RDX above 0.6 μg/L, is 3,400-feet long and 500-feet wide. The current maximum RDX concentration is lower (7.5 μg/L, MW-198M4) than the pre- RRA maximum of 35 μg/L (MW-

343M2, 2005). However, historic concentrations (37.6J μg/L) in this well indicate that the core of the RDX plume has migrated from MW-343 south and is currently down gradient of MW-227. This is also reflected in the increase in RDX concentrations in the two down gradient extraction wells

(J3EW0032 and 90EW0001). The two small RDX plumelets down gradient of monitoring wells

MW-239 and MW-157 represent migrated historical RDX concentrations and their existence has not been confirmed. While the narrow plumelet east of the down gradient RDX plume is predicted to be within the capture zone of extraction well 90EW0001 the somewhat larger plumelet located east of the J3EW1P1 extraction well is predicted to be outside of the existing ETR capture zones.

The RDX at this location is predicted to have entered and become relatively immobile in a low conductivity zone and the concentration of RDX is predicted to diminish to less than 0.6 by μg/L

Other contaminants detected in the groundwater were not retained as COCs because the contaminant was detected infrequently, the contaminants detected were essential human nutrients, or the contaminant concentrations were generally below relevant screening levels, or less than or similar to background levels. Based on the nature and extent of contamination and the risk-screening process, RDX and perchlorate were retained as COCs in groundwater

(Appendix D).

J-3 Range Response Actions

Several soil response actions have been undertaken in the J-3 Range to reduce levels of contamination from certain areas. These include soil and UXO removals at the following areas:

Area 1

Approximately 1,146 cubic yards of explosives-contaminated soils were excavated from the melt/pour building area during the 2004 RRA and thermally treated on site. Subareas excavated were located at the following locations: septic tank; suspected wastewater discharge, area west of wastewater holding tank; melt/pour building; area east of melt/pour building; and area east of septic tank.

Area 2

A total of three cubic yards of soils was excavated from the two drywells associated with the workshop building during Textron’s decommissioning activities.

Area 3

A total of 1,085 cubic yards of soils was excavated from the Demolition Area during the 2004 soil RRA and thermally treated on-site. In addition, approximately 150 cubic yards of soil were removed during Textron’s 2008 investigation activities at the Drum Disposal Area.

Locations throughout the J-3 Range

Soil sampling and geophysical investigations, and associated soil excavations were conducted from 1997 through 2010. These activities included the intrusive investigations at more than 130 geophysical anomaly locations. These investigations removed UXO from 43 locations.

In summary, soil removal actions have been conducted at numerous locations and approximately

2,400 cubic yards of contaminated soil has been excavated and treated on-site, or disposed of off-site. Cumulatively, approximately 1,900 UXO items containing high explosives were removed.

In addition, approximately 560 UXO items containing small quantities of explosives were removed along with 29,600 pounds of range debris. Textron also demolished and removed the range infrastructure, including buildings, concrete target walls, and blocks, and performed additional housekeeping measures in accordance with a Consent Decree between Textron and the EPA.

The RRA was initiated at the J-3 Range groundwater plume in 2006 to mitigate further migration of the J-3 plume until the long-term remedy could be selected for the plume. The J-3 ETR system consists of three extraction wells situated along the plume axis operating at a combined flow rate of 195 gallons per minute (gpm). Water is treated using granular activated carbon and ion exchange resin. The treatment system is housed within the nearby Fuel Spill-12 (FS-12) treatment building where the treated groundwater is fed into the FS-12 effluent system of reinjection wells. To date, the system has treated over 730 million gallons of groundwater.

Contaminant concentrations have diminished throughout most of the plume due to mass removal from operation of the ETR system and natural attenuation. As of July 2014, the system has removed more than 28 pounds of perchlorate and 4 pounds of RDX from the aquifer.

3. History of Relevant Federal and State Enforcement Activities

Federal Enforcement Activities

In February 1997, EPA Region 1 issued SDWA Administrative Order 1-97-1019 (AO1) requiring the investigation of the impact of contamination at or emanating from the training ranges and impact area upon the Sole Source Aquifer.

In May 1997, EPA issued Administrative Order 1-97-1030 (AO2), which prohibited all live firing of mortars and artillery, firing of lead from small arms, planned detonation of ordnance or explosives at or near the training ranges and impact area except for UXO activities, and certain other training-related activities.

In January 2000, EPA issued SDWA Administrative Order 1-2000-0014 (AO3), which required implementation of RRAs and Remedial Actions (RAs) to address contamination from past and present activities and sources at and emanating from the training ranges and impact area. The

RRAs specifically required by AO3 addressed elevated concentrations of contaminants in soil and have been completed. The comprehensive response action component of AO3 requires that a feasibility study, remedial design and response action be completed for several areas of concern.

Also, in 2008, the United States, on behalf of, among others, EPA, entered into a judicial Consent

Decree with Textron to address TSC’s potential liability under CERCLA for activities at the J

Ranges. Under the Consent Decree, Textron agreed to reimburse EPA $800,000 of EPA’s costs overseeing investigative and cleanup work at the training ranges and impact area, in exchange for particular covenants from liability.

C. COMMUNITY PARTICIPATION

Throughout the Site’s history, the Impact Area Groundwater Study Program (IAGWSP), EPA and

MassDEP have kept the community and other interested parties informed and involved with investigation and response activities at the J-3 Range through informational meetings, fact sheets, press releases, public comment periods and public meetings. Below is a brief chronology of public involvement efforts.

The Impact Area Review Team (IART) was a citizen advisory committee established in 1997 under AO1. The IART served as a technical/community advisory resource, allowing the EPA, the

National Guard Bureau, the Army, and MassDEP to hear first-hand the concerns of the public related to the ongoing investigation and cleanup effort at Camp Edwards. In 2007, this team was merged with the Plume Cleanup Team, the citizens’ advisory team for the Air Force Civil Engineer

Center’s Installation Restoration Program, and renamed the JBCC Cleanup Team in 2014 (JBCC

CT). The combined team meets regularly throughout the year to hear updates and provide public input on the JBCC investigations and cleanup efforts.

From 2002 through 2010, the IAGWSP briefed the Senior Management Board (SMB), which had advised JBCC organizations on environmental programs and policies. Members of the SMB included selectmen or their designated representative from the towns of Bourne, Falmouth, Mashpee, and Sandwich and representatives from the EPA, MassDEP, Massachusetts

Department of Public Health, Massachusetts National Guard, U.S. Coast Guard, and a representative from the Mashpee Wampanoag Tribe.

All IART, JBCC CT, and SMB meetings related to the Site’s investigation and response activities were advertised in the Cape Cod Times and the local edition of The Enterprise newspapers.

In October 2001, the IAGWSP, EPA and MassDEP released a Public Involvement Plan outlining activities to address community concerns and to keep citizens informed about and involved in response activities.

From the time the initial investigations at the Site began, through the present, the IAGWSP regularly presented updates on the investigation and response activities at the Site. With respect to this Decision Document, the most important updates were:

On October 15, 2014, a Public Information Session was held on the Remedy Selection

Plan for the J-3 Range at Camp Edwards. At the meeting, the IAGWSP gave a presentation on the findings of the investigations and the alternatives evaluated and EPA presented the proposed response for the Site. The JBCC CT, local residents and officials, news media representatives, and members of the public interested in site activities and cleanup decisions were invited to attend the meeting. Representatives from EPA, MassDEP and IAGWSP were available to answer questions. The IAGWSP notified the public of the information session, and reminded them about the public comment period in a display ad placed in the October 10th and October 13, 2014 editions of the Enterprise and Cape Cod Times newspapers. A news release regarding the meeting and the public comment period was sent to the local media on October 9, 2014.

From October 13 through November 13, 2014, a Public Comment Period was held on the

Remedy Selection Plan for the J-3 Range. The IAGWSP placed copies of the Remedy Selection

Plan in the IAGWSP’s information repositories at the Bourne, Falmouth, and Sandwich, MA, public libraries. The repositories contain documents on the J-3 Range investigations and findings supporting selection of the response action including the RI/FS report for the J-3 Range, along with other relevant documents. The Remedy Selection Plan also was made available on the both the EPA and IAGWSP Web sites, which also contains the supporting documents and offered a means of submitting public comments on the Remedy Selection Plan. In addition, the IAGWSP provided copies of the Remedy Selection Plan to the JBCC CT members and distributed it to individuals in attendance at the public meeting.

All draft and final reports related to the Sites’ investigation and response activities were made available through the Information Repository at the public libraries in Bourne, Falmouth, and

Sandwich, MA. These documents also were made available to the public through the IAGWSP

Web site (http://jbcc-iagwsp.org), the EPA Web site (www.epa.gov/region1/mmr) and the

Administrative Record located at PB0516 West Outer Road, Camp Edwards, MA.

Media releases on presentations and the Public Comment Period for the Site were distributed to the Cape Cod Times and other area media including newspapers, radio and television media.

Fact sheets were published and distributed regarding the Site's investigation and response activities. General fact sheets pertaining to the IAGWSP investigations and findings and on related issues, such as the contaminants of concern, were also published and distributed.

The IAGWSP, EPA, and MassDEP also participated in general information sessions, such as open houses, information sessions, community meetings and annual updates to the local Town

Managers, Boards of Selectmen, and Boards of Health on JBCC investigation and response activities.

D. SCOPE AND ROLE OF OPERABLE UNIT

The Site consists of source areas contributing to groundwater contamination (i.e., contaminated soil and the areas known or suspected to contain UXO) and a groundwater plume. Several source areas contributing to groundwater contamination from the J-3 Range were addressed through the removal of geophysical anomalies and the excavation and removal of contaminated soils. The effectiveness of the source removal will be evaluated as part of the selected remedy. The selected remedy also includes a groundwater response action for the groundwater plume. Since complete range clearance has not been conducted, UXO may remain. In addition, these remaining UXO, and the soil beneath, may also pose public safety risks, ecological risks, dermal contact risks, and/or soil ingestion risks. However, these potential UXO-related risks are not addressed by this Decision Document, which was issued pursuant to Administrative Order No.

SDWA-1-2000-0014 and Section 1431(a) of the SDWA, and which focuses on potential endangerment to the health of persons deriving from contaminants present in or likely to enter the underground source of drinking water.

E. SITE CHARACTERISTICS

Site Geology

The J-3 Range is situated within the Mashpee Pitted Plain, a thick wedge-shaped deposit of unconsolidated Late Pleistocene outwash sands and gravels. The Mashpee Pitted Plain is bounded to the west and north by Buzzards Bay and Sandwich moraines, respectively. The

Mashpee Pitted Plain is an outwash plain formed by streams that drained the Buzzards Bay and

Cape Cod Bay lobes of retreating glaciers. Depositional environments of the Mashpee Pitted Plain range from glaciofluvial for the coarser deposits to glaciolacustrine for the finer deposits. In the

Mashpee Pitted Plain, the glaciolacustrine deposits are discontinuous and commonly overlie basal till or bedrock.

Site Hydrogeology

The aquifer is situated in the permeable glacial outwash deposits overlying the relatively impermeable bedrock. The three hydrostratigraphic layers are the unsaturated zone, the saturated zone, and underlying bedrock. Groundwater flow in the saturated zone is controlled locally by the hydraulic properties of sands, silts, and clays that comprise the aquifer. The underlying bedrock represents the bottom of the aquifer. Groundwater enters the aquifer through recharge, predominantly from precipitation with minor contributions from water treatment plants, septic systems, irrigation, and other anthropogenic sources. Groundwater levels measured in July

2013 indicate that flow is from north to south and depressions in the water table illustrate the effect of groundwater extraction on the local water table (Figure 2-16). Precipitation is variable and ranges from 45 to 48 inches annually. Less than half of the precipitation is lost to evaporative processes (evaporation and transpiration).

As presented in the Final J-3 Range Groundwater Rapid Response Action (RRA) Plan, saturated hydraulic conductivities (K) in the vicinity of the J-3 Range for the Mashpee Pitted Plain sediments range from 70 to 280 feet/day with horizontal/vertical anisotropy ratios ranging from 3:1 to 25:1.

Hydraulic conductivities for glacial moraine sediments range from 22 to 150 feet/day with anisotropies similar to those for the Mashpee Pitted Plain sediments. Low-conductivity silts and silty sands are present in numerous boreholes in the area. K data for these silts and silty sands do not exist for the J-3 Range, however have been estimated based on the extensive K database and a 3-D model of Western Cape Cod’s hydrostratigraphy. In general, these fine-grain units have hydraulic conductivities less than 10 feet/day with anisotropies up to 100:1. Site-specific porosity data have not been collected from the study area. However, other studies on upper Cape Cod have indicated that the effective porosity of the coarse sand and gravel likely ranges from 0.35 to

0.42 (Masterson et al. 1997). For groundwater modeling and plume shell based estimates of mass, an effective porosity of 0.30 is assumed for the whole study area.

For the evaluation of groundwater velocities, horizontal gradients of 0.0001 and 0.0006 ft/ft (the range of gradients within the study area) were considered. Using an effective porosity of 0.3, the average linear velocities are 0.05 and 0.10 feet/day for the lowest gradient (0.0001 ft/ft). For the steepest gradient (0.0006 ft/ft), the average linear velocities increase to 0.3 and 0.6 feet/day for conductivity values of 150 and 300 feet/day, respectively.

Groundwater seepage into nearby Snake Pond in Sandwich is relevant to the J-3 Range study area because the plume is moving towards Snake Pond. The fate of the J-3 plume may be controlled by the hydraulic characteristics of the pond bottom sediments. A seepage meter study was conducted in Snake Pond in 1997 as part of an ecological studies program performed by the

Air Force Center for Engineering and the Environment. Results indicate the highest recharge and discharge rates occur close to shorelines. Seepage rates in the northern half of the pond are positive (i.e., into the pond), with a maximum as high as 0.95 foot/day. Seepage rates decrease by an order of magnitude within 250 feet of the shoreline. The southern half of the pond has negative seepage rates indicating flow of water from the pond into the aquifer, where maximum observed rates are -0.02 foot/day. Vertical hydraulic conductivities of pond bottom sediments ranged from 143 feet/day on the northwestern shore to 0.2 foot/day in the pond’s northern neck.

Mean vertical hydraulic conductivities were 23 feet/day. Higher conductivities were found in locations near Snake Pond and the northwest shore of the pond. The higher conductivities appear to be associated with moderately permeable pond bottom materials. Muck and fine grained materials are present in the deep portion of Snake Pond and in the northern neck area. The remainder of the pond is characterized by fine to coarse sands with small areas of gravel.

Conceptualization of pond bottom sediments and their impact on aquifer-pond interactions have been evaluated by the United States Geological Survey (USGS), by the Air Force Civil Engineer

Center (AFCEC) as part of the FS-12 system design efforts, and by IAGWSP as part of the J-3

RRA well field design.

Movement of Contaminants in Groundwater

Contaminated groundwater from the J-3 Range plume flows in a southerly direction and crosses the base boundary down gradient of Greenway Road. The groundwater flow rate is approximately one foot/day in the sandy portions of the unconfined aquifer which is comprised of glacial outwash deposits. Groundwater flow rates generally decrease with depth in the aquifer, where silty deposits prevail. Groundwater flow is influenced locally by discontinuous fine-grained units, hydraulic gradients, and proximity to the top of the groundwater mound.

Two COCs are present in groundwater at the Site: RDX and perchlorate. RDX and perchlorate readily leach from soil to the groundwater, with perchlorate more readily dissolving than RDX.

Movement of RDX is slightly retarded in the soil and the aquifer due to limited sorption to soil particles. Therefore, RDX will generally move at a velocity slightly less than that of normal advective flow, while perchlorate generally will move at the same rate as the advective front.

Longitudinal dispersion is a significant transport process for both perchlorate and RDX and a factor in natural attenuation.

Estimate of the Contaminant Volume and Mass

The total volume of the J-3 Range plume (based on concentrations of perchlorate greater than

2.0 ug/L and RDX greater than 0.6 ug/L as of 2013) is estimated to be 153 million gallons. The total mass of perchlorate estimated in this plume is 7.43 pounds and the total mass of RDX estimated in this plume is 1.06 pounds.

Current Exposure Pathways

There is a public water supply well located on the south side of Weeks Pond approximately one half-mile south of the J-3 Range within the J-3 Range groundwater study area. The Sandwich

Water District Weeks Pond well has been recently reconditioned and is being used on a limited basis. All but one residence in the vicinity of the J-3 plume are connected to the municipal water system and all future residents are required to use the municipal system as well. The one private water supply well is located approximately 2,000 feet southwest of the J-3 Groundwater Plume.

The IAGWSP has been sampling this well annually since 2001. No one is currently believed to be drinking water related to the J-3 Range that contains COCs at concentrations that exceed applicable drinking water standards, Health Advisories, and/or risk-based concentrations.

Potential Exposure Pathways

The development of new water supply wells and consumption of groundwater resources in areas contaminated or predicted to be contaminated by the J-3 Range plume are potential future exposure pathways. As noted above, the Cape Cod Aquifer is the sole or principal source of drinking water for Cape Cod. Portions of Camp Edwards, including the on-base portions of the

Site, have been set aside as a drinking water supply reserve by the Massachusetts legislature.

F. CURRENT AND POTENTIAL FUTURE SITE AND RESOURCE USES

The J-3 Range is located on the JBCC and is designated as an active military training area.

Contaminated groundwater from the J-3 Range plume flows in a southerly direction and crosses the base boundary down gradient of Greenway Road. It is anticipated that the J-3 Range Site will remain under the control and direction of government agencies and will continue to be used for military training and support purposes at least until the current lease expires in 2052. The J-

3 Range is also located within the Upper Cape Water Supply Reserve established pursuant to

Chapter 47 of the Massachusetts Acts of 2002 and designated as conservation land under the care and control of the Massachusetts Division of Fisheries and Wildlife. The source area overlays portions of a sole source aquifer that is designated a valued water supply for the upper portion of Cape Cod.