Demo_1_Decision_Document_Addendum_No.2_2013.pdf

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United States Environmental Protection Agency Region 1

Decision Document Addendum No. 2 Demolition Area 1

Off-base Leading Edge Groundwater Plume

Joint Base Cape Cod Cape Cod, Massachusetts

September 2013

TABLE OF CONTENTS _ PAGE

SECTION

A. SITE NAME 1

B. STATEMENT OF BASIS AND PURPOSE 2

C. ASSESSMENT OF THE SITE... 2

D. DESCRIPTION OF RESPONSE ACTION 3

1. EVALUATION OF GROUNDWATER ALTERNATIVES 3

2. RESPONSE ACTION OBJECTIVES 8

3. SELECTED RESPONSE ACTION 9

E. COMMUNITY PARTICIPATION :..18

1. THE RESPONSIVENESS SUMMARY 20

F. DETERMINATIONS 20

G: SUPPORTING DATA 21

H. AUTHORIZING SIGNATURE 21

List of Figures

Figure 1: General Location Map

Figure 2: Demolition Area 1 Groundwater Plume

Figure 3: Alternatives 3, 4 and 4A

Figure 4: Alternative 4A Treatment System Layout

Figure 5: Alternative 4A Detail

Figure 6: Land Use Control Area

List of Tables

Table 1: Summary of Alternatives Evaluation

List of Appendices

A: Massachusetts Department of Environmental Protection Letter of Concurrence

B. Glossary of Terms and Acronyms

C. Index of Key Supporting Documents

Decision Document Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume

A. SITE NAME

The subject site is the Demolition Area 1 ("the Site"), which is located at Camp Edwards at the

Joint Base Cape Cod (JBCC) formerly the Massachusetts Military Reservation-(MMR) (Figure

1). The Site is composed of a groundwater plume and a former source area which was remediated. The Demolition Area 1 Groundwater Operable Unit Decision Document , dated

November, 2006 (the. 2006 Decision' Document) established the selected remedy for the groundwater plume on the JBCC migrating from the source area. The Decision Document

Addendum No. 1 Demolition Area 1 Source Area dated September, 2009 (Addendum No. 1) established the selected remedy for the source area. This Decision Document Addendum No. 2

(Addendum No. 2) addresses groundwater contamination from Demolition Area 1 that has migrated beyond the base boundary.

An area of groundwater contaminated by explosives and perchlorate is migrating from the source area through the JBCC and into the Town of Bourne (Figure 2). The groundwater contamination was initially addressed in 2004 by an interim response action that consisted of a pump and treat system that extracted and treated 460,000 gallons of groundwater per day.

That system, which included two extraction and three injection wells, along with four modular treatment units, operated until June 2007 when it was replaced by a more comprehensive treatment system outlined in the 2006 Decision Document. The comprehensive system treated more than 1.3 million gallons per day using five extraction wells, four injection wells, one modular treatment unit and a permanent facility which replaced three of the four modular treatment units. It was predicted to restore the groundwater to risk-based levels by 2018. The

Decision Document included the contingency that additional extraction wells be added to the system if the plume was found to migrate further than expected. In 2010, monitoring wells located at the JBCC boundary showed detections of perchlorate; therefore, an additional extraction well and treatment system (currently operating at 60 gallons per minute [GPM]) were installed in June 2011 and began treating the portion of the plume that had migrated towards the base boundary. Currently the treatment system operates six extraction wells pumping at a combined rate of 665 gallons per minute. The total system treats 964,000 gallons per day and since 2006, has treated 2.2 billion gallons of groundwater and removed 109 pounds of perchlorate and 48 pounds of RQX from the aquifer.

Decision Document, Addendum No.- 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume c

B. STATEMENT OF BASIS AND PURPOSE

This Decision Document Addendum No 2. (Addendum No. 2) modifies the 2006 Decision

Document to include additional response actions to address the leading edge of the Demo 1 groundwater plume.

Addendum No. 2 supplements, incorporates, and is incorporated into and made part of the 2006

Decision Document, and every requirement in Addendum No. 2 is enforceable as a requirement of the 2006 Decision Document. The 2006 Decision Document contains the Demolition Area 1 site description, selected response action, community participation and state role.

Addendum No. 2 presents the selected response action for,the Site. 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 (A03). 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 redelegation of authorities dated April 6, 2010.

This decision is based on the Administrative Record, which has been developed in accordance with A03 and with a previous EPA Administrative Order, SDWA 1-97-1019 (A01), including-consideration of the substantivevcleanup standards of the Massachusetts Contingency Plan

(MCP) 310 CMR 40.0000. The Administrative Record is available for review at the Impact Area

Groundwater Study Program (IAGWSP) office, PB 516 West Outer Road, Camp Edwards, MA.

Key supporting documents included in the Administrative Record related to. Demolition Area 1 are listed in Appendix C.

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 Camp Edwards at JBCC are present in and may enter and

Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume September 2013 , Page 2 < migrate in the aquifer. The response actions selected in Addendum No. 2 are necessary to protect the Cape Cod Aquifer, an underground source of drinking water on which the public relies.

D. DESCRIPTION OF RESPONSE ACTION

Addendum No. 2 sets forth the selected response action taken or to be taken for addressing groundwater contamination at and emanating from the Site. Addendum No. 1 modified the 2006

Decision Document to include response actions taken to address contaminated soil, munitions and explosives associated with the Demolition Area 1 source area. Addendum No. 1 declared that no further remedial.action was necessary for the Demolition Area 1 source area.

Data collected from the Fall Of 2010 to the Winter of 2013 during a supplemental investigation indicated that perchlorate and hexahydro-1,3,5-trintiro-1,3,5-triazine (RDX) contamination exceeding acceptable levels was present beyond the JBCC boundary, with perchlorate detected as far west as County Road in Pocasset. This investigation characterized an off-base portion of the Demolition Area 1 groundwater plume over 3,700 feet west of the base boundary. The historic maximum detection in this portion of the groundwater plume was 13 ug/L of perchlorate.

In response to these findings, a base boundary extraction well and treatment system was installed as in interim measure in June 2011. This treatment system is currently operating at 60 gpm. As of August 2013, the current maximum detected concentration is 5.7 ug/L. Updated groundwater modeling also suggested that the time to achieve cleanup may extend beyond the

11 years predicted in the 2006 Decision Document. EPA required the development of a technical memorandum to evaluate alternatives for addressing the groundwater contamination that was present off base as well as alternatives to expedite cleanup of the on base contamination.

1. Evaluation of Groundwater Alternatives

Eight alternatives were developed and evaluated in the Technical Memorandum. The alternatives developed were intended to help EPA address two questions: 1) what additional actions are necessary to address the contamination that was present past the base boundary and 2) are additional actions appropriate to achieve cleanup of the plume within the timeframe

(11 years) required by the remedy selected in the 2006 Decision Document. After reviewing the

Technical Memorandum and during the development of the Remedy Selection Plan, EPA determined that Addendum No. 2 will be limited to only those alternatives addressing the off Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume

Page 3 ' ' -base contamination (Alternatives 1, 3, 4 and 4A). Correspondingly, costs presented for these alternatives reflect only the off-base portion of the remedy (Table i ) . Table 1 summarizes the alternatives which were evaluated. This table includes key information such as a description of each alternative, predicted cleanup times for both RDX and perchlorate, mass capture, and a breakdown of the costs. Figure 3 displays the placement of treatment system components for each alternative (i.e., extraction wells, treatment plants, and infiltration galleries/reinjection wells). All alternatives included Land Use Controls (LUCs), long-term groundwater monitoring, system operation and maintenance, and five year reviews.

Generally, each plume undergoes routine optimization evaluations and changes resulting from these routine optimizations are documented in the Annual Environmental Reports. If significant changes are necessary to optimize a system, a Decision Document Addendum would be issued to address those changes. At this time, only minor changes to the current on base system are recommended and those changes are not the subject of Addendum No. 2.

Detailed information on each of the four alternatives is presented below.

Alternative 1 - Current System with Monitored Natural Attenuation for the Off-base

Contamination

Alternative 1 would provide for extraction and treatment of the groundwater using the current system. Under this alternative:

• The plume located past the base boundary would be restored using monitored j natural attenuation, no further active treatment would be implemented.

• A long-term groundwater monitoring plan would be implemented and optimized as required to monitor the migration and restoration of the off base plume.

• Land Use Controls (LUCs) would be implemented to prevent use of contaminated portions of the aquifer for drinking water, and prevent actions that would interfere with the remedy.

• Monitoring, reporting and site-closeout documentation would be completed.

Contamination within the plume is expected to drop below the 2 ug/L Massachusetts Maximum

Contaminant Level (MMCL) for perchlorate by 2026 and is expected to reach background levels by 2059. RDX concentrations are expected to decrease below the 10"6 risk-based level of 0.6

Decision Document, Addendum No, 2 ' j

Demolition Area 1 Off-base Leading Edge Groundwater Plume ug/L by 2022 and reach background levels by 2025.

Alternative 3 - Current System with One Off-base Extraction Well East of Lily Pond

Alternative 3 would provide for extraction and treatment of the groundwater using the current system with modifications. Under this alternative:

• The pump and treat system would be modified to include:

One new off-base extraction well (up-gradient of Lily Pond, operating at 100 gpm, see Figure 3).

- Treatment with granular activated carbon and ion-exchange resin by expanding the base boundary treatment unit to handle the increased capacity from the off-base extraction well.

- Infiltration of the treated water with a new infiltration trench located at the base boundary.

• A long-term groundwater monitoring plan would be implemented and optimized as required to monitor the migration and restoration of the off base plume.

• LUCs would be implemented to prevent the use of contaminated portions of the aquifer for drinking water and prevent actions that would interfere with the remedy.

• Monitoring, reporting and.site-closeout documentation would be completed.

Contamination within the plume is expected to drop below the 2 ug/L,MMCL for perchlorate by

2021 and is expected to reach background levels by 2055. RDX concentrations are expected to decrease below the 10"6 risk-based level of 0.6 ug/L by 2022 and reach background levels by '

2025. The new off-base extraction well would be installed east of Lily Pond approximately at the intersection of Williams Avenue and Windrush Avenue (see Figure 3). Piping from this .

extraction well would pass under Williams Avenue, under Route 28 and back onto the JBCC property. The extraction well is located in a neighborhood which is heavily populated and has narrow roadways which could result in some disruption during construction.

This alternative requires directional drilling under Route 28, a state highway, requiring the approval of the Massachusetts Department of Transportation Highway Division. In addition, property easements would be required to construct extraction wells and associated piping.

Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume

Alternative 4 - Current System with Two Off-base Extraction Wells

Alternative 4 would provide for extraction and treatment of the groundwater using the current system with modifications. Under this alternative:

• The pump and treat system would be modified to include:

- Two new off-base extraction wells (one west and one east of Lily Pond, operating at 100 gpm each, see Figure 3).

- Treatment with granular activated carbon and ion-exchange resin by expanding the base boundary treatment unit and adding a new off-base modular treatment unit (MTU) west of Lily Pond.

- Infiltration of the treated water with a new base boundary infiltration trench and another one in an area west of Lily Pond.

• A long-term groundwater monitoring plan would be implemented and optimized as required to monitor the migration and restoration of the off base plume.

• LUCs would be implemented to prevent the use of contaminated portions of the aquifer for drinking water and prevent actions that would interfere with the remedy.

• Monitoring, reporting and site-closeout documentation would be completed.

Contamination within the plume is expected to drop below the 2 ug/L MMCL for perchlorate by

2021 and is expected to reach background levels by 2046. RDX concentrations are expected to decrease below the 10"6 risk-based level of 0.6 ug/L by 2022 and reach background levels by

2025.

A new off-base extraction well would be installed east of Lily Pond approximately at the intersection of Williams Avenue and Windrush Avenue. Piping from this extraction well would pass under-Williams Avenue, under Route 28 and back onto the JBCC property. The extraction well is located in a neighborhood which is heavily populated and has narrow roadways which could result in some disruption during construction. This alternative requires directional drilling under Route 28, a state highway, requiring the approval of the Massachusetts Department of

Transportation Highway Division.

r - •

A second off-base extraction well would also be installed on private property west.of Lily Pond along with a MTU to treat the extracted groundwater. Property easements would be required to construct extraction wells and an infiltration gallery, treatment units and the associated piping.

Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume September 2013 1

Alternative 4A - Current System with One Off-base Extraction Well West of Lily Pond

Alternative 4A would provide for extraction and treatment of the groundwater using the current system with modifications. Under this alternative:

• The pump and treat system would be modified to include:

One new off-base extraction well (west of Lily Pond, operating at 100 gpm, see

Figure 3).

- Treatment with granular activated carbon and ion-exchange resin by adding a new off-base MTU west of Lily Pond.

- Infiltration of the treated water with a new infiltration trench (west of Lily Pond).

• A long-term groundwater monitoring plan would be implemented and optimized as required to monitor the migration and restoration of the off base plume.

• LUCs would be implemented to prevent the use of contaminated portions of the aquifer for drinking water and prevent actions that would interfere with the remedy.

• Monitoring, reporting and site-closeout documentation would be completed.

Contamination within the plume is expected to drop below the 2 ug/L MMCL for perchlorate by

2025 and is expected to reach background levels by 2059. RDX concentrations are expected to decrease below the 10~6 risk-based level of 0.6 ug/L by 2022 and reach background levels by

2025. A new off-base extraction well would be installed on private property west of Lily Pond along with a MTU to treat the extracted groundwater and an infiltration trench to inject treated water back into the ground. Property easements would be required to construct extraction wells, treatment units and the associated piping.

Alternatives were evaluated using the nine criteria developed for the Comprehensive

Environmental Response, Compensation and Liability Act (CERCLA): 1) Overall protection of human health and the environment including prevention of the movement of contaminants into the aquifer and its preservation as a public drinking water supply; 2) Compliance with regulations; 3) Long-term effectiveness and permanence; 4) Reduction of toxicity, mobility and volume through treatment; 5) Short-term effectiveness; 6) Implementability; 7) Cost; 8) State

Acceptance; and 9) Community Acceptance.

With the current system operating on base, Alternatives 3, 4 and 4A included treatment of. the

Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume off-base portion of the plume. These alternatives differ in the location and number of extraction wells. All of the alternatives would be protective of human health and the environment, and are expected to be in compliance with applicable regulations. They varied in their long-term effectiveness and permanence, reduction of toxicity, mobility, or volume through treatment, short-term effectiveness, implementability and cost.

Alternatives 3, 4 and 4A provide long-term effectiveness and permanence by capture of the off-base portion of the plume. However, their predicted cleanup times for perchlorate vary from

2021 to 2025. Without the off-base extraction, groundwater modeling for Alternative 1 indicates that the plume migrates and crosses County Road, and would take until 2026 for perchlorate to reach its cleanup level. Alternatives 3, 4 and 4A provide a reduction of toxicity, mobility, or volume through treatment, and capture RDX and perchlorate (see Table 1 for capture estimates). However Alternative 4A results in the greatest mass removed through treatment.

Alternatives 3, 4 and 4A have impacts due to construction of treatment system components.

Impacts from Alternative 4A would be less than Alternatives 3 and 4 because the treatment system would be located on a private property and not within public roadways. Alternatives 3, 4 and 4A are implementable and will require extra safety precautions and coordination with the

Town of Bourne, neighborhood, private landowners, and utilities. The present worth costs for the Alternatives ranged from $3,628,000 to $5,500,000 with Alternative 4A falling in the middle with a $4,000,000 present worth cost. The capital costs ranged from $1,420,000 for Alternative

4A to $3,000,000 for Alternative 4. Both State and Community Acceptance are presented in the

State Concurrence Letter in Appendix A and Responsiveness Summary of comments received during the Remedy Selection Plan public comment period.

2. Response Action Objectives

The response action objectives for the Site 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; 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; and to prevent the ingestion and inhalation of groundwater containing the COCs (RDX, TNT, 2,4-DNT and perchlorate) in excess of. federal Maximum

Contaminant Levels (MCLs), Health. Advisories (HA), Drinking Water Equivalent Levels

(DWELs), applicable State standards or unacceptable excess lifetime cancer risk or non-cancer Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume

Hazard Index (HI).

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 15ug/L. Also, the Massachusetts Department of Environmental Protection (MassDEP) has promulgated a Massachusetts Maximum Contaminant Level (MMCL) for perchlorate of

2ug/L in July of 2006] '

The lifetime federal Health Advisory for RDX in drinking water is 2ug/L, the Massachusetts

Contingency Plan (MCP) GW-1 standard is 1 ug/L, and the 10 6 risk-based concentration that results in an increased lifetime cancer risk of one in a million is currently 0.6ug/L.

The EPA has selected a response action for the Site 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 response action will ensure that the groundwater containing -6

RDX at concentrations greater than the 10 risk-based level and/or perchlorate greater than

2ug/L is restored to protective levels.

3. Selected Response Action

• J The EPA selected response action for the Demolition Area 1 groundwater is Alternative 4A

Focused Extraction with the current extraction system (500 gpm at Frank Perkins Road, 100 gpm at Pew Road, and 65 gpm at Base Boundary) and one new off-base extraction well (west of Lily Pond, pumping at 100 gpm), Monitored Natural Attenuation, and Land Use Controls.

Extracted water from the new well will be piped to a new mobile treatment unit west of Lily Pond on private property. Treated water will be discharged to an infiltration trench. Figure'4 presents a conceptual layout of this alternative. The remedy is expected to achieve cleanup levels of

2ug/L for perchlorate by 2025 and 0.6ug/L for RDX by 2022 as contaminated groundwater is extracted and treated. In this action, land-use controls are extended off-base from the original boundary set in the 2006 Decision Document and further explained below. The alternative can be viewed as an enhancement of the current treatment systems since active treatment is added to the off-base portion of the plume. This alternative, as presented in the Demolition Area 1

Technical Memorandum, Response Action Groundwater Treatment System Analysis, provides the best balance of the criteria used to evaluate cleanup alternatives.

Decision Document, Addendum No. 2 y

Demolition Area 1 Off-base Leading Edge Groundwater Plume

The selected alternative achieves cleanup goals in a reasonable timeframe and protects human health through the use of groundwater monitoring to ensure that groundwater modeling predictions regarding the reduction and migration of contamination at the Site are correct and that any residual contamination remains below risk-based levels. Human health will be further protected through expansion of the current Land Use Controls area.' These controls will prevent use of contaminated portions of the aquifer at the Site for drinking water purposes until groundwater data confirm that contamination has been reduced to below risk-based levels.

The major components of the Demolition Area 1 response action are:

• Continued operation of the current extraction and treatment system consisting of six extraction wells operating at 665 gpm, one permanent treatment facility and two mobile treatment units (MTUs)

• Installation of one new off-base extraction well west of Lily Pond operating at 100 gpm, one off-base MTU, and a new infiltration trench (Figure 5) • • .

• Long-term groundwater monitoring at existing and new monitoring wells to verify that groundwater is being restored as predicted and to ensure that any remaining contamination remains below risk-based levels ,

• Implementation and verification of Land Use Controls 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 (See Figure 6)

• 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

The estimated capital cost of the remedy is $1,420,000 and the present worth total cost is estimated to be $4,000,000 [This cost does not include the approximately $6,000,000 associated with construction and operation of current treatment systems].

Additional data will be collected to optimize the off-base extraction well location west of Lily

Pond. Two parcels are being evaluated for locating the extraction well, mobile treatment system and infiltration gallery. There are obstacles associated with property access for these parcels.

However these obstacles are less compared to the other alternatives involving treatment (i.e., Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume September 2013-smaller parcels and narrow roadways). The IAGWSP, EPA and MassDEP will work with the owners of both parcels to determine the best location for the system components. If access issues should significantly delay the implementation of the remedy, the EPA and MassDEP will evaluate options for modifying the remedy to achieve the cleanup objectives such as proposing an alternate location for the system.

This alternative is selected because it achieves permanent cleanup of RDX and perchlorate.

This alternative restores the aquifer by actively treating the mass present, prevents migration of the plume beyond County Road and minimizes the uncertainty of letting the plume migrate un-captured. Long-term groundwater monitoring and data analysis will be conducted to optimize the system components as needed while meeting cleanup goals. Land Use Controls will be extended to off-base areas and be maintained. More detail is described in following paragraphs.

Operation & maintenance of all treatment system components will be conducted. Five year reviews will continue as part of base-wide future evaluation.

Land Use Controls

Contaminated groundwater in the Demolition Area 1 groundwater plume currently poses an unacceptable risk to human health if used for drinking water purposes. Administrative and/or legal controls that minimize the potential for human exposure to contamination by limiting land or resource use, known as "Land Use Controls" (LUCs), must be established to avoid the risk of exposure to contaminated groundwater above regulatory standards, health advisories, and/or risk-based levels, maintain the integrity of any current or future groundwater monitoring wells and treatment systems and prevent actions that would interfere with the remedy. The LUCs are needed until the groundwater contamination no longer poses an unacceptable risk.

The performance objectives of the LUCs are to:

• Prevent access to or use of the groundwater from the Demolition Area 1 groundwater plume until the groundwater no longer poses an unacceptable risk, and

• Maintain the integrity of any current or future groundwater monitoring wells and treatment systems.

The LUCs will be implemented in the areas encompassing the Demolition Area 1 groundwater Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume September 2013 , plume contaminated groundwater and surrounding areas to prevent risks from exposure to contaminated groundwater. The on-JBCC areas of concern are controlled and operated by the

Massachusetts National Guard in conjunction with the US Army (Army) which leases the land from the Commonwealth of Massachusetts. It is expected that these entities will operate and lease, respectively, the Site and the surrounding area's for the duration of the remedy specified in this Decision Document. As a result, , the Army will coordinate with the Commonwealth of

Massachusetts as it fulfills its' responsibility to establish, monitor, maintain and report on the

LUCs for the Sites. Although homes located in the off-JBCC area have been connected to town water, an additional land use control will be necessary within the Town of Bourne for the areas within the downgradient portion of the Demolition Area 1 groundwater plume.

Each land use control will be maintained until either (1) the concentrations of RDX and perchlorate in the groundwater are at levels that allow for unrestricted use and unlimited exposure, or (2) the Army, with the prior approval of the EPA, in consultation with MassDEP, modifies or_terminat.es the land use control in question.

Specific Land Use Controls

The Army is responsible for ensuring that the following land use controls are established, monitored, maintained, reported on, and enforced as part of this final remedy to ensure protection of human health in accordance with SDWA § 1431(a) for the duration of the final remedies selected in this Decision Document. The Town of .Bourne has enforcement authority regarding the first land use control, which is applicable to the off-JBCC portion of the Demolition

Area 1 groundwater plume. The Commonwealth of Massachusetts has enforcement authority regarding the second land use control, which applies to all sites. The Massachusetts Air

National Guard and Massachusetts Army National Guard have enforcement authority regarding the third and fourth land use controls, which are applicable to the on-base portions of the Site.

The Air Force has enforcement authority regarding the fifth land use control, which is applicable to the on-JBCC portions of the Site.

1. The Bourne Board of Health requires a permit for the installation and use of all wells, including drinking water wells, irrigation wells, and monitoring wells. No well will be allowed to be constructed for human consumption or irrigation if its placement is known to. be over a known plume of contamination or in the direct

Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume path of an advancing plume of contamination. The minimum lateral distance from potential contamination sources is 400 feet. If a permit to install a drinking water well is approved, the Bourne Board of Health will not approve the use of that well until its water has been tested and the Board of Health has determined that the water is potable. The Bourne Board of Health Well Regulations do not apply to use of existing drinking water wells and irrigation wells.

To assist the Town of Bourne in the implementation of this land use control, the

Army will meet with the Bourne Board of Health on an annual basis, or more frequently if needed, to provide and discuss plume maps that document the current and projected location of the Demolition Area 1 groundwater plume within the town of Bourne., While Figure 6 shows the current area of land use controls in the town, the Bourne Board of Health may modify the areas where the Board of Health may require additional well testing, and this land use control will apply to such areas even if they differ from the area shown.

2. In addition to the Town of Bourne Board of Health regulations, which generally apply to small water supply wells, existing land use controls also prevent the possible creation of a large potable water supply well. MassDEP administers a permitting process for any new drinking water supply wells in Massachusetts that propose to service more than 25 customers or exceed a withdrawal rate of

100,000 gallons per day. This permitting process, which serves to regulate the use of the Demolition Area 1 groundwater plume area for any new withdrawals of groundwater for drinking water purposes, constitutes an additional land use control for these final remedies. This land-use control applies to both on-JBCC and off-JBCC areas. (Existing public water supply wells will remain subject to permits currently in place.)

3. • For on-JBCC areas, a prohibition on new drinking water wells serving 25 or fewer customers has been established and placed on file with the planning and facilities offices for the Massachusetts Air and Army National Guard (major tenants at the JBCC). The prohibition will be applied to future land-use planning per Massachusetts Air National Guard Instruction (ANGI) 32-1003, Facilities

Decision Document, Addendum No. 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume

Board and Massachusetts Army National Guard Regulation 210-20, Real

Property Development Planning for the Army National Guard.

4. For the on-post area's, the Massachusetts Air National Guard has administrative processes and procedures that require approval for all projects involving construction or digging/subsurface soil disturbance, > currently , set forth in

Massachusetts Air National Guard Instruction 32-1001, Operations Management.

This procedure is a requirement of the Massachusetts Army National Guard, by the Massachusetts Air National Guard, through Installation Support Agreements.

The Massachusetts Air National Guard requires a completed AF Form 103, Base

Civil Engineer Work Clearance Request (also known as the base digging permit), prior to allowing any construction, digging, or subsurface soil disturbance activity.

All such permits are forwarded to the Army for concurrence before issuance. An

AF Form 103 will not "be processed without a Dig Safe permit number (see next paragraph).

5. The Dig Safe program implemented in Massachusetts provides an added layer of protection to prevent the installation of water supply wells in the Central Impact

Area groundwater area and to protect monitoring wells. This program requires, by law, anyone conducting digging activities (e.g., well drilling) to request clearance through the Dig Safe network. The Air Force at the JBCC is a member utility of Dig Safe. The Camp Edwards Training Range and Impact Area, fall

• within the geographical area identified by the Air Force as a notification region within the Dig Safe program. Through the Dig Safe process, the Air Force will be electronically notified at least 72 hours prior to any digging within this area. The notification will include the name of the party contemplating, and the nature of, the digging activity. Upon receiving Dig Safe notification of any proposed digging activity on Camp Edwards (whjch includes the Impact Area), the Air Force will promptly transmit the Dig Safe notification information to the Army, with a copy to the Massachusetts National Guard JBCC Environmental & Readiness Center

(E&RC). The Army (or its designee) will promptly review each notification and if the digging activity is intended to provide a previously unknown water supply well, the Army, (or its designee) will immediately notify the project sponsor (of the

Decision Document, Addendum No. 2 ~ , - Demolition Area 1 Off-base Leading Edge Groundwater Plume well drilling), the EPA, and the MassDEP in order to curtail the digging activity. If the Dig Safe notification indicates proposed work near monitoring wells, the Army

(or its designee) will mark its components to prevent damage due to excavation.

The extent of the Army's enforcement of this land use control does not address off-base parties failing to file a Dig Safe request or the improper processing of a notification; but if incidents do occur, the Army is responsible for ensuring remedy integrity and, if necessary, repairing damage, caused by third parties to the monitoring wells or treatment systems.

In the event that the Town of Bourne fails to promptly enforce the first land use control, the

Commonwealth of Massachusetts fails to promptly enforce the second land use control, the

Massachusetts Air and Army National Guards fail to promptly enforce the third or fourth land use control, or the Air Force fails to promptly enforce the fifth land use control, the Army will act in accordance with the third to last paragraph in this section, headed "Activities Inconsistent

With Land Use Controls." Specifically, if the Army discovers that the party responsible for enforcing the identified land use control has failed to promptly enforce that land use control, then, as soon as practicable, but no later than 10 days after the Army becomes aware of this failure to promptly enforce the land use control, the Army will notify the EPA and MassDEP and initiate actions to address such failure. The Army will notify the EPA and MassDEP regarding how the Army has addressed or will address the breach within 10 days of sending the EPA and

MassDEP notification of the breach; For purposes of this paragraph, "promptly enforce" means if the violation or potential violation is imminent or on-going, enforce to ,prevent or terminate the violation within 10 days from the enforcing agency's (i.e., the Town's, Commonwealth's, Massachusetts Air and Army National Guards', or Air Force's) discovery of the violation or potential violation; otherwise, enforce as soon as possible.

Private Wells

The LUCs are intended to pTevent exposure to groundwater impacted by the plumes. However, to ensure that the LUCs achieve the LUC performance objectives, the Army will take the following additional action with respect to the Demolition Area 1 plume.

Within three years of the signing of this Decision Document, the Army shall:

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a. Document all private wells (i.e., non-decommissioned wells, including wells not currently in use) located on or off the JBCC that are above or within the projected path of the Demolition Area 1 groundwater plume.

b. Demonstrate and document that the private well is not capable of drawing

'contaminated groundwater originating from the Demolition Area 1 groundwater plume, or

/" test the private well for contamination and demonstrate the private well to be safe for

.human use. The Army will continue such testing, on an appropriate frequency as determined in coordination with the EPA and MassDEP, until the plume no longer presents a threat to that well as determined in coordination with EPA and MassDEP.

c. If the Army identifies a well containing COCs, the Army shall assess the risk that current and potential future non-drinking uses of such a well pose to human health. The '

Army shall submit a draft version of any such risk assessment to EPA and MassDEP for review and EPA approval.

d. If neither b nor c is able toNconfirm that the identified well is safe for human use, the

Army will offer the owner decommissioning of the well. If accepted, the Army will document such action with the Bourne Board of Health, the EPA and MassDEP. If the decommissioning is not accepted, the Army will take other steps to ensure protectiveness to include, but not be limited to, requesting assistance from the Bourne

Board of Health to issue health warnings to the property owner and any other person with access to the well (such as a lessee or licensee), offering bottled water (if well is

' used for drinking), or installing treatment systems on affected wells. In each instance, the Army shall submit a schedule subject to EPA concurrence, outlining and including time limitations for the completion of steps sufficient to prevent exposure to concentrations of contaminated groundwater from the Demolition Area 1 groundwater plume having COCs in excess of cleanup levels.

Monitoring *

Monitoring of the land use restrictions and controls will be conducted annually by the Army. The monitoring results will be provided annually in a separate report or as a section of another

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monitoring report, and provided to the EPA and MassDEP. The reports will. be used in preparation of the Five-Year Review to evaluate the effectiveness Of the .final remedy.

The annual monitoring report, submitted to the regulatory agencies by the Army, will evaluate the status of the LUCs and. how any LUC deficiencies or inconsistent uses have been addressed. The annual evaluation will address (1) whether the use restrictions and controls referenced above were put in place and effectively communicated, (2) whether the operator, owner, and state and local agencies were notified of the use restrictions and controls affecting the property, and (3) whether use of the property has conformed with such restrictions and controls and, in the event of any violations, summarize what actions have been taken to address the violations. In addition, the Annual Monitoring Report will include a discussion of the efforts undertaken during the past year to complete the tasks outlined in "Private Wells" above.

Operational Responsibilities and Liability

Upon approval by EPA, after consultation with MassDEP, the Army may transfer various operational responsibilities for LUCs (i.e., monitoring) to other parties, through agreements.

However,, the Army acknowledges its ultimate liability under the SDWA § 1431(a) for remedy integrity.

Activities Inconsistent With Land Use Controls 1

For any proposed land use change(s) that would be inconsistent with the land use control objectives or the final remedy, the Army shall seek EPA review and concurrence at least 45 days prior to any proposed land-use change(s). In addition, if the Army discovers a proposed or ongoing activity that would be or is inconsistent with the land-use control objectives or use restrictions, or any other action (or failure to act) that may interfere with the effectiveness of the land use controls, it will address this activity or action as soon as practicable, but in no case will the process be initiated later than 10 days after the Army becomes, aware of this breach. The

Army will notify the EPA and MassDEP as soon as practicable, but no later than 10 days after the discovery of any activity that is inconsistent with the LUC objectives or use restrictions, or any other action that may interfere with the effectiveness of the LUCs. The Army will notify the

EPA and MassDEP regarding how the Army has addressed or will address the breach within 10 days of sending the EPA and MassDEP notification of the breach.

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Ensuring Continued Maintenance of LUCs

The Army will provide notice to the EPA and MassDEP at least six months prior to relinquishing the lease to the areas related to the Demolition Area 1 groundwater plume so the EPA and

MassDEP can be involved in discussions to ensure that appropriate provisions are included in the transfer terms or conveyance documents to maintain effective LUCs. If it is not possible for the Army to notify the EPA and MassDEP at least six months prior to any transfer or sale of property located within the Demolition Area 1 groundwater plume, then the Army will notify the

EPA and MassDEP as soon as possible, but no later than 60 days prior to the transfer or sale of any property, subject to LUCs.

The Army shall not modify or terminate LUCs or implementation actions, or modify land use without approval by the EPA, in consultation with MassDEP. The Army, in coordination with other agencies using or controlling the Demolition Area 1 groundwater plume area, shall obtain prior approval before taking any anticipated action that may disrupt the effectiveness of the r

LUCs or any action that may alter or negate the need for LUCs. The Army will provide EPA and

MassDEP 30 days notice of any changes to the internal procedures for maintaining land-use controls which may affect the Demolition Area 1 groundwater plume area.

E. COMMUNITY PARTICIPATION

From the time the initial investigations at the Site began, through the present, the IAGWSP regularly presented updates to the MMR Cleanup Team, a citizen advisory group established to inform and involve the public, on -the investigations and response activities at the Site. With respect to this Addendum, the most important updates were:

• On July 24, 2013, an informational meeting was held at Camp Edwards, MA, to describe the Remedy Selection Plan for the Demolition Area 1 site to the MMR Cleanup Team and the public. At the, meeting, the IAGWSP gave a presentation on the Site, the Remedy Selection

Plan and EPA's proposed response and answered questions from the MMR Cleanup Team and the public. The IAGWSP notified the public of the meeting in a display ad placed in the July 18 and July 25 editions of The Enterprise newspapers. In addition, information about the public comment period and an invitation to the information session was mailed to Bourne residents on

July,15, 2013.

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• At the request of the community, a second informational meeting was held on August 8, 2013 in Pocasset at the Pocasset Community Club. At the meeting, the IAGWSP displayed posters with information on the Site, provided the Remedy Selection Plan and answered questions from the public. The IAGWSP notified the public of the meeting in a display ad placed in the August 1 edition of The Enterprise newspapers. In addition, information about the public comment period and an invitation to the information session was mailed to Bourne residents on

July 31, 2013. .

• From July 17, 2013 through August 16, 2013, a Public Comment Period was held on the

Remedy Selection Plan for Demolition Area 1. The IAGWSP placed copies of the Remedy

Selection Plan in the lAGWSP's information repositories at the Bourne, Falmouth, and

Sandwich, MA, public libraries. The repository contains documents on Demolition Area 1 investigations and findings supporting selection of the response action including the Technical

Memorandum for Demolition Area 1, along with other relevant documents. The Remedy

Selection Plan also was made available on the IAGWSP Web site, which also contains the supporting documents and which offered a means of submitting public comments on the

Remedy Selection Plan. In addition, the IAGWSP provided copies of the Remedy Selection

Plan to MMR Cleanup Team members and distributed it to individuals in attendance at the public meeting and public hearing. The IAGWSP notified the public of the public comment period in a display ad placed in the July 18 and July 25 editions of The Enterprise newspapers

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: www.mmr-iagwsp.org and the Administrative Record by appointment at PB 516 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.

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, Decision Document, Addendum No, 2 Demolition Area 1 Off-base Leading Edge Groundwater Plume

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

Throughout the course of the Demolition Area 1 off-base investigations, four paid advertisements and six neighborhood notices were distributed to Pocasset residents to provide updates on the investigations. In addition, a presentation was made at the Spring 2013 Bourne

Town meeting. '

1. Responsiveness Summary

The following table provides a summary of the response to a comment which was received during the public comment period held on the remedy selection plan for Demolition Area 1 from

July 17 through August 16, 2013.

Name of Comment Originator

Alve Hart

Organization of Comment Originator

Falmouth Resident

Comment

I am deeply concerned about the Plume at now Otis Air Base. As a resident of Falmouth, MA since I was 1 yr old and now age 75, I support the new plan to ensure levels of perchlorate and RDX by 2018.

It is costly to buy bottled water and environmentally absurd not to not take action to have safe drinking water.

This negligence has gone on too long - hope your efforts will support this plan.

Response

Preference for the alternative proposed in the Remedy Selection Plan is noted.

F. 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

Addendum, issued pursuant to A03 and Section .1431 of . the SDWA, addresses the unacceptable threats to the groundwater aquifer from the site.

As required by A03, the selected alternatives for the Site (Operation of the current system with one off-base extraction well, Monitored Natural Attenuation and Land Use Controls) provides a level of protection to the aquifer underlying and downgradient of the Site commensurate with the

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