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Table of Contents

Acronyms and Abbreviations

Appendices

Executive Summary

This Engineering Evaluation/Cost Analysis (EE/CA) is issued by the Air Force Center for Environmental Excellence (AFCEE) under the Installation Restoration Program (IRP) at the Massachusetts Military Reservation (MMR). This EE/CA supports a non-time critical removal action at area of concern (AOC) Chemical Spill No.22 (CS-22).

This EE/CA also identifies removal action objectives (RAOs). The specific RAOs for AOC CS-22 are summarized as follows:

• prevent exposure to humans and ecological receptors from metals and polycyclic aromatic hydrocarbon (PAH) contaminated soil, and

• mitigate potential impact to groundwater by petroleum hydrocarbons.

This document was prepared in accordance with the U.S. Environmental Protection Agency (USEPA) guidance on preparing EE/CAs and is intended to comply with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).

A preliminary assessment (PA) /site investigation (SI) conducted at AOC CS-22 has identified the presence of metals, PAHs, chlorinated volatile organic compounds (VOCs), and petroleum hydrocarbons in surface soil. Concentrations of metals and PAHs have been detected at levels that may have adverse effects on ecological receptors and humans. Additionally, concentrations of petroleum hydrocarbons have been found which exceed Massachusetts Department of Environmental Protection (MADEP) S-1/GW-1 standards.

Three alternatives were evaluated in this EE/CA. They include (1) No Action, (2) Institutional Controls and Soil and Groundwater Modeling, and (3) Excavation, Off-site Disposal, and Site Restoration. The proposed alternative is Alternative Three which includes the excavation of approximately 1,200 cubic yards of contaminated soils to depths of two to three feet below ground surface (bgs). All of the soil to be excavated is expected to be classified as nonhazardous waste and transported to an off-site disposal facility. After confirmation sampling has been completed, the excavated area would be backfilled and revegetated. The cost of the proposed removal action is $530,500. This removal action is expected to remove soil contaminated with contaminants of concern (COCs) above removal action levels (RALs), which are considered protective of human health and the environment. Additionally, this removal action will be used in the development of the final decision for cleanup at the site.

The public and other stakeholders will have an opportunity to comment on this non-time critical removal action. Contingent upon acceptance by regulatory agencies, the public, and other stakeholders, an action memorandum will be prepared to initiate implementing the removal action.

1.0 Introduction

As a component of the Department of Defense (DoD) IRP, AFCEE conducted this EE/CA in support of a non-time critical removal action at AOC CS-22 at the MMR. The EE/CA was developed based on the recommendations of a SI completed in 2001 (AFCEE 2001a).

The MMR consists of facilities operated by the U.S. Coast Guard (USCG), Massachusetts Army National Guard (ARNG), U.S. Air Force (USAF), Air National Guard (ANG), Veterans Administration (VA), and Commonwealth of Massachusetts. The collective complex occupies approximately 22,000 acres and is located on Cape Cod, Massachusetts (Figure 1-1). Military use of portions of MMR began as early as 1911; the majority of activity at MMR has occurred since 1935. Remedial studies and activities are currently being conducted at the MMR under the DoD IRP in accordance with the guidelines and procedures of the USEPA Superfund Program and the NCP. Subpart E of the NCP establishes the methods and criteria for the appropriate extent of remedial response authorized by CERCLA.

The CS-22 study area is located near the east-central portion of MMR (Figure 1-2). The site consists of a former sand and gravel borrow pit located west of Greenway Road and south of Dolan Road near the MMR access gate at the northeastern end of Snake Pond Road in Sandwich, Massachusetts.

1.2 Summary of Geology and Hydrogeology

The CS-22 study area is located in the Mashpee Pitted Plain (MPP). The MPP consists primarily of stratified, well to poorly sorted, fine to coarse-grained sands forming a broad outwash plain. During the excavation of the petroleum-contaminated soils at CS-22 (see section 1.4), a clay layer was encountered approximately two feet bgs on the down-slope end of the excavation.

The single groundwater flow system that underlies the CS-22 area is known as the Sagamore lens. AOC CS-22 is located southwest of the top portion of the groundwater recharge mound for the Sagamore lens. Surface water bodies in the vicinity of CS-22 include Snake Pond and Weeks Pond. Snake Pond and Weeks Pond are located approximately 1 and 0.5 miles, respectively, northeast and crossgradient of the CS-22 Study Area. Groundwater beneath CS-22 flows in a southern direction.

1.3 Environmental Investigations

A PA and SI were performed for CS-22. These investigations are summarized below.

A PA was completed for the CS-22 site in 1999 (AFCEE 2000a). The PA identified an area of petroleum-contaminated soil near the northwest end of the gravel pit and 11 small debris areas, most of which are concentrated near the southeast end of the gravel pit. The debris areas contained miscellaneous refuse consisting primarily of construction/demolition debris, asphalt and household waste. Prior to the PA, previous site work consisted of the collection and analysis of two soil samples from the northern portion of the petroleum-contaminated soil area in March 1999. The Massachusetts Army National Guard collected additional samples and excavated approximately 418 tons of soils from this area during the spring of 2000.

The objectives of the CS-22 SI were to provide confirmatory sampling of the petroleum-contaminated soil excavation; determine if waste materials associated with debris areas elsewhere in the gravel pit had contributed to soil contamination; determine if groundwater beneath the site is captured by the existing Chemical Spill-10 (CS-10) extraction, treatment and reinjection systems; determine if a potential risk to human health or ecological receptors exists; and determine appropriate follow-on actions (AFCEE 2001a). Figure 1-3 presents CS-22 SI sampling locations. The soil analytical results were

compared against Massachusetts Contingency Plan (MCP) Method 1 S-1/GW-1 soil standards and USEPA Region IX Residential Preliminary Remediation Goals (PRGs). Both of these standards are considered extremely conservative and provide a "worst case" scenario for potential risk. Provided below is a summary of the nature and extent of contamination identified as part of the 2001 SI.

Confirmatory Sampling of the Petroleum-Contaminated Soil Excavation: Eleven surface soil samples (0-6 inches bgs) were collected in and around the petroleum-contaminated soil excavation. These were analyzed for VOCs, semivolatile organic compounds (SVOCs), metals, volatile petroleum hydrocarbons (VPH), extractable petroleum hydrocarbons (EPH), and explosive compounds. Surface (0-6 inches bgs) and shallow subsurface soil (18-24 inches bgs) samples were also collected at each of six debris areas and were analyzed for VOCs, SVOCs, metals, and explosive compounds.

Only three sampling locations exceeded MCP Method 1 S-1/GW-1 standards for EPH, and all of these are located at the southern end of the excavation. Acetone, 1,1,2,2-tetrachloroethane, tetrachloroethene, bis(2-ethylhexyl)phthalate, and metals were also detected, but below MCP Method 1 S-1/GW-1 standards. Aluminum, arsenic and iron concentrations exceeded USEPA Region IX PRGs. However, most of the metals results were well below established background concentrations for MMR soils (the exceptions were those samples that also exceeded MCP Method 1 S-1/GW-1 soil standards for EPH). No explosives compounds were detected.

Debris Piles: The analytical results of surface (0-6 inches bgs) and shallow subsurface (18-24 inches bgs) soil samples from the area of the debris piles, and subsequent risk evaluation, indicate that PAHs exceed MCP Method 1 S-1/GW-1 standards at three of the six locations sampled. At all but one location, the soils exceeding MCP Method 1 S-1/GW-1 standards for PAHs were limited to the 0- to 6-inch interval with the associated 18- to 24-inch intervals below regulatory cleanup levels. Acetone, phthalates, and metals were also detected, but below MCP Method 1 S-1/GW-1 standards. Explosive compounds were not detected. Concentrations of several PAHs, aluminum, arsenic and iron exceeded USEPA Region IX PRGs. Most of the metals results (including aluminum, arsenic and iron) were below established background concentrations for MMR soils.

Groundwater Modeling: Groundwater modeling demonstrates that any release of contamination from the site to groundwater would be captured by the CS-10 In-Plume treatment system. There is no field data to suggest that a release of contamination from the site to groundwater occurred earlier than 26 years ago; if such a release occurred, it likely would have already migrated beyond the capture zone of the Sandwich Road well fence.

Conclusions: Based on the results of the SI, representatives from the USEPA, MADEP and AFCEE agreed in March 2001, that AFCEE should proceed with an EE/CA to address soil contaminated with petroleum hydrocarbons and PAHs at site CS-22. It was also agreed that no further groundwater investigation was required.

Additional sampling was performed to further delineate petroleum contamination and PAH contamination at AOC CS-22. For the purposes of this effort, AOC CS-22 was divided into a northern portion and a southern portion. The scope of work for the northern portion of the site included the collection of 12 surface soil samples from six locations around the perimeter of the southern end of the previous excavation as described in Section 1.4. Samples were analyzed for extractable petroleum hydrocarbons (EPH) using MADEP methodology. No concentrations of EPH were above respective MCP Method 1 S-1/GW-1 Standards.

The scope of work for the southern portion of the site included the collection of 83 soil samples from 41 locations. These samples were analyzed for total carcinogenic PAHs using an on-site immunoassay field screening method. Thirteen of the 83 soil samples that were field-screened were also submitted for laboratory analysis of individual PAH compounds. Four of the soil samples contained levels of individual PAH compounds in excess of applicable MCP Method 1 S-1/GW-1 soil standards. These soil samples were collected from the inside perimeter encircling the debris pile associated with sample 83SS0013. This data indicates that although low-levels of PAHs are detected throughout this area, soils exceeding regulatory cleanup levels are limited to the three locations initially identified during the 2001 SI, 83SS0013, 83SS0014, and 83SS0015 respectively.

During the spring of 2000, the Camp Edwards Environmental Protection Office supervised the removal of approximately 418 tons of soil from the petroleum contaminated soil area in the northern portion of AOC CS-22. There were several detections above the MCP Method 1 S-1/GW-1 standards. The maximum total petroleum hydrocarbons (TPH) concentration detected was 12,000 mg/kg. The soil excavation was initiated by the Camp Edwards Facility Engineering Department on 08 March 2000 and was completed by Clean Harbors Environmental Services, Inc. (under the supervision of the Camp Edwards Environmental Protection Office) on 17 July 2000. Soil removed from the site was stockpiled at a fenced and locked compound in the 3500 block of Camp Edwards prior to removal from the installation. The stockpiled material was stored on top of and was completely covered by weighted polyethylene plastic at all times. The stockpile was subsequently transported by truck to American Reclamation Corp., a MADEP-licensed soil recycling facility in Charlton, Massachusetts. The soil was disposed in accordance with the MADEP Interim Remediation Waste Policy for Petroleum Contaminated Soils (WSC-94-400).

Preliminary Risk Evaluation: A preliminary risk evaluation (PRE) was performed to evaluate risk to hypothetical residential receptors that could potentially be exposed to soil contaminants in the future. The CS-22 study area lies near the east-central boundary of the MMR just west of the Sandwich gate. No occupied structures are within the CS-22 study area; however, there are private residences outside of the MMR boundary approximately one-quarter mile east of the site.

Seventeen locations were sampled, and maximum concentrations were screened against Region IX residential PRGs, at a risk level of 1 x 10^-6 and an HI of 0.1, and MCP Method 1 S-1/GW-1 soil standards. Chemicals exceeding either of these criteria were identified as contaminants of potential concern (COPCs). After COPCs were identified, maximum concentrations were compared to background values obtained from AMEC Earth and Environmental Draft Technical Memorandum 01-4 Distribution of Soil Chemicals for the Camp Edwards Impact Area Groundwater Quality Study. This study was prepared for the National Guard Bureau. However, please note that the background study has not been finalized. The use of residential PRGs to identify COPCs in a non-residential area is an extremely conservative approach as it assumes that a site resident is exposed to soils 350 days per year. Furthermore, many of the Region IX PRGs are below established background concentrations for MMR soils.

Three inorganic compounds (aluminum, arsenic, and iron) and eight organic compounds benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene] exceeded screening criteria and were identified as COPCs in soil. Furthermore petroleum hydrocarbon classes C11-C22 aromatic hydrocarbons and C19-C36 aliphatic hydrocarbons exceeded MCP S-1/GW-1 standards. The maximum concentrations exceeding human health screening criteria and background values were observed at locations 83SS0009 and 83SS0013. Table 1-1 presents COPCs identified and maximum concentrations detected in samples collected at CS-22.

* denotes classes of compounds

Post SI Risk Analysis: In order to be consistent with removal and remedial actions for the Source Area Remedial Action Program (SARAP), AFCEE selected human–health risk based COCs to be addressed by this EE/CA based on the comparison of analytical data of COPCs selected by the SI with the most stringent human health risk-based soil target cleanup levels (STCLs) developed during the Drainage Structure Removal Program (DSRP) Program. Table 1-2 presents the Human Health Risk Based COCs. If concentrations of COPCs exceeded these levels, they were retained as human-health COCs.

* denotes classes of compounds

The following chemicals were retained as COCs: arsenic, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, C11-C22 aromatic hydrocarbons, C19-C36 aliphatic hydrocarbons, Dibenz(a,h)anthracene and Indeno(1,2,3-c,d)pyrene. Development of RALs, which includes comparison of the most stringent soil target cleanup level (STCL) with background will be presented in Section 2.

The ecological PRE analyzes potential risks from chemicals to ecological receptors, assuming no further actions are taken at the CS-22 site. The assessment determined whether contaminants at the site pose ecological risks of significant magnitude to warrant further evaluation and/or remedial action. The components of the assessment include problem formulation, exposure assessment, effects assessment, and risk characterization.

The landscape surrounding the CS-22 site is dominated by disturbed pitch pine (Pinus rigida)-mixed oak (Quercus spp.) forest with a scrub oak understory (Quercus ilicifolia). Within the limits of the CS-22 site, the dominant vegetation transitions to immature pitch pine saplings with a sparse understory of native shrubs and grasses. A stand of mature big-toothed aspen (Populus grandidentata) trees is located adjacent to the site access road.

A single wetland known as the Unit Training Equipment Site pond is located northeast of the CS-22 site. Also, two smaller wetlands are located southeast of the site. Snake and Weeks ponds are located northeast of the site.

The CS-22 site is located within an area designated by the Massachusetts Natural Heritage and Endangered Species Program as a priority habitat of rare species. However, no rare species of plants or animals protected by the Massachusetts Endangered Species Act have been documented at the site. Furthermore, no federally-listed threatened or endangered plants or animals have been documented to exist within the CS-22 study site.

Risk characterization integrates the results of the exposure and effects assessments to estimate risks. Because only abiotic data were available for this assessment, the principal line of evidence is the single chemical toxicity data, which indicate the toxic effects of the concentrations measured in the site media. Hazard Quotients (HQs) greater than 1 suggest that the chemical may be hazardous to the end-point biota and, therefore, worthy of further assessment. HQs less than one suggest that the chemical is nonhazardous and need not be considered further.

Maximum concentrations were screened against diet benchmarks for the short-tailed shrew, white-footed mouse, and the red fox. A summary of the screening for each endpoint species is discussed below:

Short-Tailed Shrew: For the short-tailed shrew, maximum total concentrations for seven inorganic compounds (aluminum, arsenic, barium, chromium, lead, selenium, vanadium) and one organic compound (benzo(a)pyrene) exceeded their respective no observed adverse effects level (NOAEL) benchmarks. The exceedances occurred at locations 83SS0009 and 83SS0013.

White-Footed Mouse: For the white-footed mouse, maximum total concentrations for five inorganic compounds (aluminum, arsenic, barium, lead, vanadium) exceeded their respective NOAEL benchmarks. The exceedances occurred at location 83SS0009.

Red Fox: For the red fox, maximum total concentrations for seven inorganic compounds (aluminum, arsenic, barium, chromium, lead, selenium, vanadium) and one organic compound (benzo(a)pyrene) exceeded their respective NOAEL benchmarks. The exceedances occurred at locations 83SS0009 and 83SS0013.

Earthworms absorb a variety of inorganic and organic soil contaminants through both feeding in soil and litter, and burrowing in soil. It is assumed these organisms represent highly exposed soil invertebrates. Because earthworms and other soil invertebrates may spend their entire lives at a single sampling location, the maximum detected contaminant concentrations are used to assess potential negative impacts of contaminated soil on soil invertebrate populations. Maximum concentrations were screened against benchmarks derived for earthworms. Benchmarks were unavailable for 33 of the detected analytes. The calculated HQ of 68.75 for chromium exceeded 1. The maximum concentration (27.5 mg/kg) occurs at location 83SS0009.

Contaminants exceeding their respective benchmarks or an HQ of 1 for terrestrial wildlife or invertebrates were identified as chemical of potential ecological concern (COPECs). Seven metals and one organic compound were identified as COPECs in soil. A comparison of maximum concentrations to background values, for the identified COPECs, revealed that background concentrations were occasionally exceeded for all seven inorganic compounds (aluminum, arsenic, barium, chromium, lead, selenium, vanadium) and one organic compound [benzo(a)pyrene]. Most of the samples, however, contained inorganics at concentrations below established background concentrations for MMR soils. Table 1-3 presents ecological COPECS.

In order to be consistent with removal and remedial actions for the SARAP, AFCEE selected ecological - risk based COCs to be addressed by this EE/CA based on comparison of analytical data of COPECs selected by the SI with ecological risk based STCLs developed in 2001 (inorganics); STCLs developed as part of the DSRP program (organics only); and STCLs considered protective of terrestrial plants and invertebrates. Table 1-4 presents ecological COPECs that were retained as COCs.

All COPECs were retained as ecological risk-based COCs. RALs to address these COCs are developed and presented in Section 2.0.

The sampling results of the SI indicate that AOC CS-22 contains chemicals at levels that pose risk to ecological receptors and humans. The 2001 SI recommended a removal action of soil containing these COCs for the protection of human health and the environment. Presented in Table 1-5 are the selected COCs and the applicable risk-based criteria (human-health and/or ecological). Section 2.0 presents removal action objectives intended to address these COCs.

* denotes classes of compounds

This section provides removal action justification, a summary of the regulatory requirements, and the objectives for developing removal alternatives. Subsection 2.1 outlines the justification for soil removal at CS-22. Subsection 2.2 discusses the definition of applicable or relevant and appropriate requirements (ARARs).

ARARs and identifies potential chemical- and location-specific ARARs for the study areas. Potential action-specific ARARs and the applicability of the ARARs pertinent to each removal alternative in this EE/CA are discussed in Section 4.0, Evaluation of Removal Action Alternatives. Subsection 2.3 presents the RAOs and subsection 2.4 presents the development of RALs.

The NCP states that a removal action may be conducted at a site when a threat to human health or welfare or the environment is determined. An appropriate removal action is undertaken to abate, minimize, stabilize, mitigate, or eliminate the release or the threat of release at a site. Section 300.415 of the NCP outlines factors to be considered when determining the appropriateness of a removal action, such as high concentrations of hazardous substances, pollutants, or contaminants in soil, largely at or near the surface, that may migrate or present a threat of fire or explosion.

Once it is decided that a removal action is appropriate, a determination is made whether the removal is an "emergency", "time-critical", or "non-time-critical" removal. "Emergencies" are those removals in which response actions must begin within hours or days after completion of the site evaluation. "Time-critical" removals are those for which, based on a site evaluation, it is determined there are less than six months available before on-site response activities must begin. "Non-time-critical" removals are those for which it is determined there are more than six months available before removal actions must begin.

The 2001 SI Report for the AOC CS-22 recommended a "non-time-critical" removal action at Study Area CS-22 based on identification of COCs that present an ecological and/or human health risk. Furthermore, two classes of compounds (i.e., petroleum hydrocarbons and Target Analyte List (TAL) chlorinated VOCs are to be addressed by this removal action due to potential impact to groundwater This EE/CA documents the identification and evaluation of a removal action alternative in support of this "non-time-critical" removal action.

ARARs are federal and state human health and environmental requirements used to (1) evaluate the appropriate extent of site cleanup; (2) scope and formulate alternatives; and (3) guide the implementation and operation of a selected action. NCP Section 300.415(I) establishes that removal actions are required to attain "to the extent practicable, considering the exigencies of the situation, all state as well as federal ARARs." To determine whether compliance with ARARs is practicable, factors such as the urgency and scope of the removal action should be considered. Scope relates to the special nature of removals in that they may be used to minimize and mitigate potential harm rather than totally eliminate it. Therefore, even though a particular standard may be an ARAR for a particular medium, it may be outside the scope of the removal action when such cleanup is not necessary for stabilization of the site. The scope of the removal action at AOC CS-22 is limited to removal of localized areas of soil contamination at each study area.

Under CERCLA Section 121(e), permits are not required for response actions conducted entirely on-site. This permit exemption applies to administrative permit requirements (e.g., documentation, recordkeeping, and enforcement). However, compliance with the substantive requirements of applicable regulations must be achieved.

The NCP defines three categories of potential requirements in the remedial response process: (1) applicable requirements, (2) relevant and appropriate requirements, and (3) information to be considered (TBC) guidance. These definitions are discussed in the following paragraphs.

Applicable Requirements are clean-up standards, standards of control, and other substantive environmental protection requirements, criteria, or limitations promulgated under federal or state law that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance at a site.

Relevant and Appropriate Requirements are clean-up standards, standards of control, or other substantive environmental protection requirements, criteria, or limitations, promulgated under federal and state law, that while not applicable to a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance, address problems or situations sufficiently similar to those encountered at the site that their use is well suited. Portions of a requirement may be relevant and appropriate even if the entire requirement is not.

To Be Considered (TBC) Guidance are advisories or guidance issued be federal or state government that are not legally binding and do not have the status of potential ARARs. They are considered in the absence of federal or state ARARs, or when such ARARs are not sufficiently protective.

Under the description of ARARs set forth in the NCP and Superfund Amendments and Reauthorization Act (SARA), State and federal ARARs are categorized as:

• Chemical-specific ARARs are typically health- or risk-based numerical values or methodologies that establish site-specific acceptable chemical concentrations or amounts. These values are used to develop action levels or clean-up concentrations;

• Location-specific ARARs set restrictions on chemical concentrations or conduct of activities solely because they are in special locations; and

• Action-specific ARARs regulate the performance and design of remedial activities.

A discussion of chemical- and location-specific ARARs follows. Once remedial action alternatives have been developed, alternative-specific, and action-specific ARARs are identified in Subsection 4.2. Subsection 4.2 also presents an evaluation of each alternative with respect to compliance with ARARs.

Chemical-specific ARARs are usually health- or risk-based standards that limit concentrations of chemicals found in or, discharged to the environment. These ARARs govern the extent of site remediation by providing either actual clean-up levels or the basis for calculating such levels.

There are no promulgated federal standards for soil. PAHs and petroleum hydrocarbons were identified as COCs. RALs for PAHs with the exception of Benzo(a)pyrene were based on MCP Method 1 S-1/GW-1 standards. For petroleum hydrocarbons and PAHs with the exception of benzo(a)pyrene, MCP Method 1 S-1/GW-1 standards are considered chemical-specific ARARs, and are used as RALs. Chemical-specific ARARs and TBC Guidance are summarized in Table 2-1.

AFCEE developed RALs for inorganic compounds that are considered protective of ecological receptors. Please note that RALs based on MMR-specific STCLs, are not considered chemical-specific ARARs or TBC. Development of these RALs are discussed in Section 2.4.

Benzo(a)pyrene was identified as both a human health and ecological COC. For human health, the MCP S-1/GW-1 standard is the chemical-specific ARAR. However, because the ecological STCL (derived from the MMR Risk Assessment Handbook) is more stringent, the State ARAR is only applicable for depths greater than two feet.

2.2.2 Location-Specific Applicable or Relevant and Appropriate Requirements

Location-specific ARARs pertain to special locations (i.e., wetlands, floodplains, sensitive ecosystems, or places of historical or archeological significance). These ARARs generally place restrictions on the concentration of hazardous substances or the conduct of activities solely based on the site’s particular characteristics or location. Areas of critical environmental concern and habitats for endangered species were identified at MMR during a 1984 Natural heritage Survey (Massachusetts Natural Heritage Program 1984). However, soil removal activities at AOC CS-22 are not anticipated to disturb these locations. Location-specific ARARs are listed in Table 2-2.

Action-specific ARARs are technology- or activity-based limitations that direct how remedial actions are conducted. The applicability of this set of requirements is directly related to the particular remedial activities selected for the sites. These requirements are presented for each alternative in Section 4.0 of this EE/CA. Evaluation of action-specific ARARs is one criterion for assessing the feasibility and effectiveness of remedial alternatives, and is discussed in Section 4.0.

Removal action objectives were developed based on these considerations and were established to achieve the overall objective of protecting human health and the environment. The specific RAOs for AOC CS-22 are summarized as follows:

• prevent exposure to humans and ecological receptors from metals and polycyclic aromatic hydrocarbon (PAH) contaminated soil, and

• mitigate potential impact to groundwater by petroleum hydrocarbons.

The objectives identify responses that are necessary to adequately address human-health and ecological risks, as well the potential groundwater impact posed by contaminated soil.

Removal Action Levels based on evaluation of MMR site-specific STCLs also take into account MMR site–specific background. Table 2-3 presents the selected COCs and corresponding RAL. Please note that the background values for the development of these RALs were obtained from the background study performed as part of the MMR Risk Assessment Handbook. The only exception was chromium. The background value for chromium (19 mg/kg) was obtained from the Camp Edwards background study. The background value was approved by USEPA based on the agency’s review of the Table entitled "Soil Target Cleanup Levels Driven by Inorganic and/or PCB Risk" (see Appendix A for USEPA approval letters).

 

Table 2-3: Chemicals of Concern and Respective Removal Action Levels
Chemical	Basis of Selection	RAL (mg/kg)	Comments
Aluminum	Ecological	8,900 mg/kg (Background) (0-2ft. bgs)	Most stringent ecological STCL was for phytotoxicity (50 mg/kg). However, the RAL selected is the site-specific background (8,900 mg/kg).
Arsenic	Ecological Human	3.6 mg/kg (Background) (0-15 ft. bgs)	Ecological STCL calculated in Technical Memorandum Revised Ecological Soil Target Cleanup Levels for Inorganics at Massachusetts Military Reservation Jan. 2001. Lowest calculated ecological STCL was for the meadow vole (1 mg/kg). RAL approved February 8, 2001 [refer to USEPA RAL approval letter dated February 8, 2001 (See Appendix B)]. The lowest human health STCL is 0.366 mg/kg. However, the RAL selected is the site-specific background (3.6 mg/kg).
Barium	Ecological	52 mg/kg (Ecological – Meadow Vole) (0-2 ft bgs.)	Ecological STCL calculated in Technical Memorandum Revised Ecological Soil Target Cleanup Levels for Inorganics at Massachusetts Military Reservation Jan. 2001. Lowest calculated STCL was for the meadow vole (52 mg/kg). RAL approved February 8, 2001 [refer to USEPA RAL approval letter dated February 8, 2001 (See Appendix B)].
Chromium	Ecological	19 mg/kg (Background) (0-2 fts bgs)	Most stringent ecological STCL was for phytotoxicity (1 mg/kg). However, the RAL selected is the site-specific background (19 mg/kg).
Lead	Ecological	99 mg/kg (Background) (0-2 ft bgs)	Ecological STCL based on lower end of critical soil range (100 mg/kg) (refer to Table O-4 of the MMR RAH) used to calculate hazard quotient to determine phytotoxicity. Value was adjusted to 99mg/kg due to proposed background. Ecological RAL approved May 2, 2001 [refer to USEPA RAL approval letter dated May 2, 2001 (See Appendix C)].
Selenium	Ecological	Background (0.33 mg/kg) (0-2 ft bgs)	Ecological STCL calculated in Technical Memorandum Revised Ecological Soil Target Cleanup Levels for Inorganics at Massachusetts Military Reservation Jan. 2001. Lowest calculated STCL was for the Meadow Vole (0.19 mg/kg). RAL approved February 8, 2001 [refer to USEPA RAL approval letter dated February 8, 2001 (See Appendix B)]. However site-specific background was selected as the RAL.
Vanadium	Ecological	15 mg/kg (Background) (0-2 ft. bgs)	Lowest calculated STCL was for phytotoxicity (2 mg/kg). However site-specific background (15 mg/kg) was selected as the RAL.
Benzo(a)anthracene	Human	0.7 mg/kg (MCP S-1/GW-1) (0-15 ft. bgs)	MCP S-1/GW-1 standard is the most stringent human-health STCL.
Benzo(a)pyrene	Human, Ecological	0.625 mg/kg (DSRP-bird) (0-2 ft. bgs) 0.7 mg/kg (MCP S1/GW-1) (2-15 ft bgs)	DSRP STCL for protection of birds was more stringent than for protection of human heath, therefore was selected as RAL from 0-2ft bgs. The RAL for > 2 feet bgs is 0.7 mg/kg (MCP S-1/GW-1 standard)
Benzo(b)fluoranthene	Human	0.7 mg/kg (MCP S-1/GW-1) (0-15 ft. bgs)	MCP S-1/GW-1 standard is the most stringent human-health STCL.
Indeno(1,2,3,-c,d)pyrene	Human	0.7 mg/kg (MCP S-1/GW-1) (0-15 ft. bgs)	MCP S-1/GW-1 standard is the most stringent human-health STCL.
Petroleum Hydrocarbons	Human/Impact to Groundwater	Total: 200 Aliphatic C5-C8: 100 C9-C12 :1,000 C13-C-18: 1,000 C19-C36: 2,500 Aromatic C9-C10: 100 C11-C22 :200 (0-15 ft bgs)	RAL for petroleum hydrocarbons is based on MCP S1/GW1 Standards.
TAL Chlorinated Volatile Organic Compounds	Impact to Groundwater	TBD	Impact to Groundwater RALs are currently being developed. Samples will be collected at the bottom of excavations to determine if further delineation is required.

Petroleum hydrocarbons and PAHs were detected in surface soils. The MADEP has established standards for protection of groundwater and human health. Removal of petroleum hydrocarbon and PAH contaminated soil to MCP Method 1 S-1/GW-1 standards are considered protective of human health and is expected to mitigate impact to groundwater. The MCP Method 1 S-1/GW-1 standards are considered chemical-specific ARARs.