Final Site4ROD.pdf

Naval Facilities Engineering Command Mid-Atlantic Norfolk, Virginia

Final Record of Decision

Site 4–Very Low Frequency Peninsula

Naval Support Activity Cutler Cutler, Maine

September 2019

Distribution Statement A - Approved for public release: distribution unlimited

Naval Support Activity Cutler Final Site 4 Record of Decision i September 2019

TABLE OF CONTENTS

SECTION PAGE NO.

ACRONYMS ................................................................................................................................................ iii

1.0 DECLARATION

1.1 Statement of Basis and Purpose

1.2 Assessment of Site

1.3 Description of Selected Remedy

1.4 Statutory Determinations

1.5 ROD Data Certification Checklist

1.6 Authorizing Signatures

2.0 DECISION SUMMARY

2.1 Site Name, Location, and Brief Description

2.2 Site History and Enforcement Activities

2.3 Community Participation

2.4 Scope and Role of Operable Unit

2.5 Site Characteristics

2.5.1 Physical Characteristics

2.5.2 Conceptual Site Model

2.5.3 Nature and Extent and Fate and Transport of Contamination

2.6 Current and Potential Future Site and Resource Uses

2.7 Summary of Potential Chemical Risks

2.7.1 Summary of Human Health Risk

2.7.2 Summary of Ecological Risk

2.7.3 Basis for Action

2.8 Remedial Action Objective

2.9 Description of Alternatives

2.10 Comparative Analysis of Alternatives

2.11 Principal Threat Waste

2.12 Selected Remedy

2.12.1 Rationale for Selected Remedy

2.12.2 Description of Selected Remedy

2.12.3 Expected Outcomes of Selected Remedy

2.13 Statutory Determinations

2.14 Documentation of Significant Changes

2.15 State Role

3.0 RESPONSIVENESS SUMMARY

3.1 Stakeholder Comments and Lead Agency Responses

3.2 Technical and Legal Issues

REFERENCES .......................................................................................................................................... R-1 ii September 2019

TABLES

NUMBER

1-1 ROD Data Certification Checklist 2-1 Previous Investigations and Site Documentation 2-2 Receptors and Exposure Routes Evaluated in the HHRA 2-3 Summary of RME Cancer Risks and Hazard Indices 2-4 Site 4 Cleanup Levels 2-5 General Response Actions 2-6 Summary of Soil Remedial Alternatives Evaluated 2-7 Summary of Comparative Analysis of Alternatives 2-8 How the Selected Remedy Mitigates Risks/Hazards and Achieves RAOs

FIGURES

NUMBER

1-1 Site Location and Layout 2-1 Conceptual Site Model 2-2 Tower and Helix House Estimated Excavation Areas 2-3 Transformer House S-4 Proposed Excavation Areas

APPENDICES

A PROPOSED PLAN AND PUBLIC NOTICE

B ARARs

C COST ESTIMATE

D RESPONSIVENESS SUMMARY

iii September 2019

ACRONYMS

ALM Adult Lead Model

AOC Area of Concern

ARAR Applicable or Relevant and Appropriate Requirement

Bgs Below ground surface

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

C.F.R. Code of Federal Regulations

COC Chemical of concern

COPC Chemical of potential concern

CSF Cancer slope factor

CTE Central tendency exposure

EPA United States Environmental Protection Agency

EPC Exposure point concentration

ERA Ecological risk assessment

FS Feasibility Study

HHRA Human health risk assessment

HI Hazard Index

HQ Hazard Quotient

IEUBK Integrated Exposure Uptake Biokinetic

ILCR Incremental lifetime cancer risk

ISM Incremental sampling methodology

LUC Land use control

MEDEP Maine Department of Environmental Protection

MNA Monitored natural attenuation

NCTAMS LANT Det Naval Computer and Telecommunications Area Master Station Atlantic Detachment

NSA Naval Support Activity

NCP National Oil and Hazardous Substances Pollution Contingency Plan

NPW Net present worth

PCB Polychlorinated biphenyl

PRG Preliminary remediation goal

RAO Remedial action objective

RD Remedial Design

Rd. Reference dose

RI Remedial Investigation

RME Reasonable maximum exposure iv September 2019

ROD Record of Decision

RSL Regional Screening Level

SEV Screening ecological value

TDD Total daily dose

TRV Toxicity reference value

UCL Upper confidence limit

VLF Very Low Frequency

1 September 2019

1.0 DECLARATION

1.1 STATEMENT OF BASIS AND PURPOSE

This Record of Decision (ROD) presents the selected remedial action for Site 4, Very Low Frequency (VLF) Peninsula, located at Naval Support Activity (NSA) Cutler, also known as Naval Computer and Telecommunications Area Master Station Atlantic Detachment (NCTAMS LANT Det Cutler), located in Cutler, Washington County, Maine.

The VLF Peninsula, located within the secured boundaries of the NSA Cutler, extends into the Gulf of Maine and is bordered on the west by Machias Bay and on the east by Little Machias Bay. (see Figure 1-1). The VLF Peninsula is the location of the antenna towers that make up the North and South VLF Antenna Arrays and North and South Helix Houses, which support the antenna array network. In 2002, the VLF Peninsula was identified as Operable Unit 4 in an Administrative Order by Consent signed by the Navy and Maine Department of Environmental Protection (MEDEP). The 2002 Administrative Order by Consent indicated that discharges of hazardous substances occurred at NSA Cutler that may present a danger to the public and the environment and required the Navy to take response actions to protect public health and the environment. NSA Cutler is not on the National Priorities List; therefore, it is not in the Comprehensive Environmental Response, Compensation, and Liability Information System database. Installation Restoration sites at NSA Cutler are being addressed under the State of Maine Uncontrolled Hazardous Substance Site Law (Maine Revised Statute Title 38, Chapter 13-B). The Navy is the lead agency for response actions taken under the Administrative Order by Consent, with MEDEP as the lead regulatory agency. The Administrative Order by Consent specifies that the Navy will implement response actions at NSA Cutler in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

This decision document presents the Selected Remedy for Site 4, which was chosen in accordance with CERCLA, as amended by the Superfund Amendments and Reauthorization Act, and, to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The decision outlined in this ROD is based on information contained in the Administrative Record for the facility.

FIGURE 1-1. SITE 4 LOCATION AND LAYOUT

2 September 2019

Information not specifically summarized in this ROD or its references but contained in the Administrative Record has been considered and is relevant to the decision; thus, the decision summarized in this document is based on and relies on the entire Administrative Record file. The Administrative Record for NSA Cutler (including records applicable to the Site 4) is available for public review as part of the Information Repository at the Porter Memorial Library in Machias, Maine, and Louise Clements Library in Cutler, Maine.

Documents in the Information Repository are also available online at:

https://www.navfac.navy.mil/products_and_services/ev/products_and_services/env_restoration/administr ative_records.html?p_instln_id=CUTLER_NCTAMS.

1.2 ASSESSMENT OF SITE

The response action selected in this ROD is necessary to protect the public health or welfare or the environment from actual or threatened releases of hazardous substances into the environment. Action is required because concentrations of polychlorinated biphenyls (PCBs) and lead in soil pose unacceptable risks to human health under current industrial/commercial and potential future residential and recreational land use scenarios.

1.3 DESCRIPTION OF SELECTED REMEDY

The Selected Remedy for Site 4 includes the following components:

Excavation and off-site disposal of soil with concentrations of chemicals of concern (COCs) greater than cleanup levels protective of industrial and construction workers.

Implementation of land use controls (LUCs) to prohibit future use of the site for residential or recreational purposes, to require proper management of future excavated soil, and to prevent disturbance of building foundations.

The Selected Remedy eliminates unacceptable human health risks associated with exposure to soil by removing from the site soil with COC concentrations exceeding industrial and construction worker cleanup levels and by preventing potential future residential and recreational uses of the site using LUCs. The Selected Remedy is expected to achieve substantial long-term risk reduction and allow the property to be used for the current and reasonably anticipated future industrial-type use of the site. This ROD documents the final remedial action for Site 4 and does not include or affect any other Installation Restoration sites at the facility. Implementation of this remedy is consistent with current use and the overall cleanup strategy for NSA Cutler to cleanup sites to support base operations.

1.4 STATUTORY DETERMINATIONS

The Selected Remedy is protective of human health and the environment, complies with federal and state requirements that are applicable or relevant and appropriate to the remedial action, is cost-effective, and utilizes permanent solutions and alternative treatment (or resource recovery) technologies to the maximum extent practicable. The Selected Remedy does not satisfy the statutory preference for remedies that use treatment as a principal element to reduce the toxicity, mobility, or volume of hazardous substances, pollutants, and contaminants. Treatment of soil chemical contamination was deemed impracticable based on the relatively low concentrations and low migration potential of the contaminants.

Because this remedy will result in hazardous substances, pollutants, or contaminants remaining on site in excess of levels that allow for unlimited use and unrestricted exposure, a statutory review will be conducted within 5 years of initiation of the remedial action to ensure that the remedy is, or will be, protective of human health.

1.5 ROD DATA CERTIFICATION CHECKLIST

The locations in Section 2.0, Decision Summary, of the information required to be included in the ROD are summarized in Table 1-1. Additional information can be found in the Administrative Record file for NSA Cutler.

3 September 2019

TABLE 1-1. ROD DATA CERTIFICATION CHECKLIST

DATA LOCATION

COCs and their respective concentrations Sections 2.5 and 2.7

Baseline risk represented by the COCs Section 2.7

Cleanup levels established for COCs and the basis for these levels Section 2.8

How source materials constituting principal threats are addressed Section 2.11

Current and reasonably anticipated future land use assumptions and potential future beneficial uses of groundwater used in the risk assessment

Section 2.6

Potential land and groundwater uses that will be available at the site as a result of the Selected Remedy

Section 2.12.3

Estimated capital, operations and maintenance, and total net present worth (NPW) costs; discount rate; and number of years over which the remedy costs are projected

Appendix E

Key factors that led to the selection of the remedy Section 2.12.1

4 September 2019

1.6 AUTHORIZING SIGNATURES

This Record of Decision (ROD) documents the Selected Remedy for Installation Restoration Site 4, VLF Peninsula, at Naval Support Activity (NSA) Cutler. This decision was selected by the Navy with the concurrence of Maine Department of Environmental Protection (MEDEP). Concur and recommended for immediate implementation:

Daniel W. Ettlich Date Captain, United States Navy Installation Commanding Officer Portsmouth Naval Shipyard

David Wright Date Division Director Bureau of Remediation and Waste Management Maine Department of Environmental Protection

5 September 2019

2.0 DECISION SUMMARY

2.1 SITE NAME, LOCATION, AND BRIEF DESCRIPTION

NSA Cutler, located on the coast of the Gulf of Maine near the Town of Cutler, Maine, was established on June 23, 1961, as a communications facility providing radio signal transmissions to Navy ships, planes, and submarines in the North Atlantic Ocean, Arctic Ocean, and Mediterranean Sea. The installation was initially composed of three parcels of land including the Administrative and Housing Area, High Frequency Area, and VLF Area. In 2003, the approximately 80-acre former Administrative and Housing Area was transferred by the Navy to the Cutler Development Corporation. The approximately 100-acre High Frequency Area is not currently active. The VLF Area, which continues to operate on Navy-owned land, is situated on a 2,860-acre peninsula and consists of cleared and forested land, transmitter towers, and support buildings.

The VLF Peninsula is approximately 1,800 acres in size and occupies the southern portion of Cutler’s VLF Area. The VLF Peninsula is the location of the Cutler VLF transmitter, which supports two VLF antenna arrays consisting of a northern array and a southern array. The panels (webs of cables attached to the towers) in each antenna array are supported by 13 main towers including a center tower surrounded by six inner ring towers and six outer ring towers. The main towers are approximately 800 to 1,000 feet tall. Each main tower is supported by one or two counterweights, which are each supported by a tower that is approximately 200 feet tall, in addition to six 90-foot support towers located around the helix houses. The main towers and counterweight towers are coated with alternating bands of orange and white-colored paint.

Also included as part of Site 4 are the 24 VLF transformer houses, one at each main tower, that were originally identified as Area of Concern (AOC) 16. PCBs in caulking material used along the roof of these buildings was released to surrounding soil as the material weathered. The areas around these buildings were investigated separately from the rest of Site 4, but the sites were combined in 2018 based on the presence of PCBs in surface soil and the locations of the VLF transformer houses within the Site 4 footprint.

Soil contamination associated with these VLF transformer buildings will be addressed as part of the Site 4 remedial action.

Situated within the Site 4 footprint is Site 7, the South Helix House, where a spill of PCB-containing oil from an electrical transformer switch has impacted soil. The South Helix House is located adjacent to Tower S- 0 in the Southern Antenna Array and occupies less than 1 acre of land. Cleanup of Site 7 is being addressed separately by the Navy.

2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES

Table 2-1 provides summaries of investigations that have been completed at the VLF Peninsula. The documents listed in this table are available in the NSA Cutler Administrative Record and provide detailed information used to support the remedial action decision for Site 4.

TABLE 2-1. PREVIOUS INVESTIGATIONS AND SITE DOCUMENTATION

INVESTIGATION DATE ACTIVITIES

Technical Assistance Visit

During the Engineering Field Activity Northeast and MEDEP Technical Assistance Visit, soil and sediment samples were collected from areas around eight towers, and sediment and stream samples were collected from areas adjacent to these towers.

Varying levels of PCBs and lead were detected in soil and sediment around the towers.

MEDEP

Sampling Package

MEDEP conducted marine sediment and biota (clams and mussels) sampling adjacent to the VLF Peninsula and at a reference area. PCBs and elevated levels of metals were detected, but it was determined that the data were not of sufficient quality to be used in risk assessments.

Spatial Variability Pilot Study

During this study, soil samples were collected to evaluate the spatial variability of lead concentrations at varying distances from three towers. Lead concentrations were determined to be directly proportional to the proximity of the towers (concentrations were greater at closer proximities), lead and PCB concentrations

6 September 2019

TABLE 2-1. PREVIOUS INVESTIGATIONS AND SITE DOCUMENTATION

INVESTIGATION DATE ACTIVITIES

appeared biased to areas with visible paint chips, and most paint chip-related contamination appeared limited to the top 4 inches of soil.

Fall 2004 Sampling Program

This investigation, conducted to further evaluate the nature and extent of paint chip-related contamination, included collection of surface soil samples (0 to 2 inches below ground surface [bgs]) around 10 towers (20 at each tower), co-located near-surface soil samples (2 to 6 inches bgs) in areas around 3 of the 10 towers where paint chips were visible (12 additional samples), and 50 freshwater sediment samples from targeted areas of sediment accumulation across the peninsula. Soil data indicated that, in general, lead and PCB concentrations in surface soil decrease significantly beyond 100 feet from the bases of the towers. Sediment results were considered adequate and were used in the Remedial Investigation (RI) risk assessments, but it was decided, based on lack of consensus on sample collection and processing techniques required to address the variability of sampling results, that the soil results were not sufficiently representative of Site 4 contamination to support risk assessments. The unacceptably high variabilities in concentrations was primarily because the paint chip-related chemicals were concentration in the small paint chips rather than in the surrounding soil.

Soil Sample Collection and Homogenization Pilot Study

2007-

This two-phase pilot study was conducted to evaluate various sample collection and processing methods for reducing the variability of sampling results. The results were used to develop the RI soil sampling technique, which involved collection of multiple samples over a 150- by 150-foot area called an exposure unit, combining the samples, and then grinding the combined (composite) samples to reduce particle sizes and reduce concentration variability in the composite samples. This method resulted in samples considered representative of concentrations available to human and ecological receptors at the site.

RI, Phases 1 through 4

2011-

Composite surface soil (0 to 4 inches bgs) samples, near-surface soil (4-12 inches bgs) samples, surface and near-surface freshwater and marine sediment samples, and marine and terrestrial biota (shellfish and earthworm) samples were collected to determine the nature and extent of paint chip-related contamination. During the four phases of the RI, 213 soil (147 surface and 66 near-surface), 81 freshwater sediment (42 surface and 39 near-surface), and 81 marine sediment (41 surface and 40 near-surface) samples were collected. Earthworm samples were collected from 18 locations, and shellfish were collected from 37 locations. Soil and biota sample results from the RI and sediment sample results from the RI and fall 2014 sampling event (47 surface and 6 near-surface sediment samples) were used to estimate human health and ecological risks associated with Site 4 contamination.

AOC 16 Site Inspection

2015-

Soil samples were collected from each of the 24 transformer houses to delineate the extent of PCB contamination associated with releases from building caulking.

Samples of the caulking material and wipe samples from building floors and exterior walls were also collected. PCB concentrations in soil around 18 of the 24 buildings exceed the Site 4 PCB cleanup level of 17 mg/kg for industrial workers.

North Helix House (NHH) Soil Sampling

Additional soil sampling was conducted in 2017 at AOC 17 (NHH Storage of PCB Oil and Equipment), located at the NHH within Site 4 to determine the areas of lead-contaminated soil that require removal to meet the cleanup level established for the site in the Feasibility Study (FS). Results indicating isolated areas of soil around buildings with lead concentrations greater than the cleanup level will be incorporated into the design for the Site 4 remedial action.

FS 2017

Based on the results of the RI, an FS was conducted to develop and evaluate soil remedial alternatives.

VLF Transformer Houses (Formerly AOC

16) Alternatives Evaluation Technical Memorandum

Alternatives to cleaning up PCB contamination in soil around the VLF transformer houses to meet the Site 4 total PCB cleanup level for industrial workers were evaluated. The recommended alternative was soil excavation to industrial cleanup levels and LUCs.

7 September 2019

TABLE 2-1. PREVIOUS INVESTIGATIONS AND SITE DOCUMENTATION

INVESTIGATION DATE ACTIVITIES

Proposed Plan 2018 Presented the Navy’s Preferred Alternative to address contamination.

There have been no cited violations under federal or state environmental law or any past or pending enforcement actions pertaining to the cleanup of the VLF Peninsula.

2.3 COMMUNITY PARTICIPATION

The NSA Cutler Information Repository is available online at https://www.navfac.navy.mil/ products_and_services/ev/products_and_services/env_restoration/administrative_records.html?p_instln_i d=CUTLER_NCTAMS and at the Porter Memorial Library, 92 Court Street, Machias, Maine, and Louise Clements Library, 2655 Cutler Road, Cutler, Maine. Documents and other relevant information relied on in the remedy selection process are available for public review at the Information Repository, which includes a copy of the Administrative Record. For additional information about the Installation Restoration Program at NSA Cutler, contact Naval Facilities Engineering Command Mid-Atlantic, Public Affairs Officer, 9324 Virginia Avenue, Norfolk, Virginia, 23511, NAVFAC_ML_PAO@navy.mil.

In accordance with Sections 113 and 117 of CERCLA, the Navy provided a public comment period from September 7 to October 8, 2018, for the preferred remedial action described in the Proposed Plan for Site

4. A public meeting to present the Proposed Plan was held on September 26, 2018, at the Bay Ridge Elementary School in Cutler, Maine. Public notices of the meeting and availability of documents were published in the Ellsworth American on August 30 and September 20, 2018, and Machias Valley News Observer on August 29 and September 19, 2018. The Proposed Plan and public notices are included in Appendix A.

2.4 SCOPE AND ROLE OF OPERABLE UNIT

Site 4 is one of several locations identified at NSA Cutler for assessment and cleanup under the CERCLA process. Each of these locations is undergoing the CERCLA cleanup process independently. The proposed remedial action for Site 4 is not expected to have any impact on the cleanup of other sites at NSA Cutler.

No further action has been approved for all of the 33 Areas of Concern identified at NSA Cutler. No further action was also approved for a former skeet range known as UXO 1. A total of nine sites, including Site 4, have been identified at NSA Cutler. No further action has been approved for five sites (Sites 3, 5, 6, 8, and 9). Proposed Plans have been finalized and RODs are in progress for Sites 1, 2, and 7.

Investigations at Site 4 have identified the presence of soil contamination that poses unacceptable human health risks to current and potential future site users. The remedy documented in this ROD will achieve the remedial action objective (RAO) for Site 4, as listed in Section 2.8. Implementation of this remedy will allow continued use of the site to support base operations, which is consistent with current and reasonably anticipated future industrial-type use of the site.

2.5 SITE CHARACTERISTICS

This section presents summaries of Site 4 physical characteristics, the conceptual site model, and nature and extent and fate and transport of contaminants. Human health and ecological receptors are discussed in Section 2.7. Detailed information about the site is presented in the documents listed in Table 2-1.

2.5.1 Physical Characteristics

The VLF Peninsula occupies approximately 1,800 acres of cleared and wooded land and is generally flat to gently sloping from north to south. The Navy leveled and cleared the area during construction of the antenna network. Maximum site elevations are generally in the central portion of the site, with topography sloping downward to the west, south, and east toward the Gulf of Maine. Ground surface elevations in the Northern Array range from 15 to 75 feet above mean sea level, and elevations in the Southern Array range from 15 to 80 feet above mean sea level. Surface water on the VLF Peninsula includes approximately 1,427 acres of wetland and several perennial and intermittent streams. Vegetation on the VLF Peninsula is primarily

8 September 2019 maintained grasses and low shrubs. Vegetation is cleared at least once per year in approximately 90 percent of VLF Peninsula upland areas. Other habitat includes open meadow, some forested/scrub-shrub habitat, and palustrine, estuarine, and forested wetlands.

Soils at NSA Cutler are classified as the Presumpscot Formation and are characterized by glacio-marine deposits consisting of clayey silt with surficial sand deposits from glacial till and marine sediments. Glacio-marine material was deposited during the last glacial period (i.e., Wisconsin Glacial Episode), approximately 12,020 to 13,320 years ago. Glacial till at the facility is a heterogeneous mixture of gravel, sand, silt, and clay. Both basal and ablation glacial till are found on the VLF Peninsula. Basal till is characterized by fine-grained and very compact material that was deposited at the base of the glacier as the glacier advanced.

Ablation till is characterized by loose, sandy, and stony material that was deposited as the glacier stagnated and retreated. Glacial marine sediments (mostly clayey silts) were deposited when the area was depressed by the weight of the continental glacier, causing most of the area to be submerged (Battelle, 2005).

Bedrock underlying NSA Cutler is classified as metasedimentary rock of the Quoddy Formation and is composed mostly of rhyolite, basalt, argillite, shale, and siltstone. Surface soil in some areas on the VLF Peninsula are thin (less than 10 feet thick) or absent, exposing the underlying bedrock (Tetra Tech, 2010).

A fault trends southwest-northeast and bisects the area south of the Administrative and Housing Area. A second fault zone with two faults trends southwest-northeast and bisects the VLF Peninsula (EA, 1999).

Groundwater investigations at Site 4 were limited by the presence of a subsurface copper mat that is part of the VLF antenna system. The exact depths to groundwater throughout Site 4 are unknown; however, groundwater at the South Helix House was encountered at approximately 8 feet bgs while collecting subsurface soil samples using a hand auger during 1999 soil sampling (Tetra Tech, 2010).

2.5.2 Conceptual Site Model

Figure 2-1, the conceptual site model for Site 4, summarizes the contaminant sources, ways in which the contaminants were released and transported, receptors evaluated as part of the risk assessment, and how those receptors could potentially come into contact with the contamination under current and future land use scenarios.

2.5.3 Nature and Extent and Fate and Transport of Contamination

Contaminants at the Site 4 antenna array towers and helix houses are associated with aviation orange and white paints previously used to paint the towers. The towers have been repainted several times since their construction in the late 1950s/early 1960s, and paint chips were deposited on the ground surface when deteriorating paint containing metals and PCBs was removed to allow for repainting. PCBs were reportedly added to the white tower paint during the 1967 and 1968 repainting events to improve the adhesive properties of the paint. Repainting of the towers no longer involves release of paint chips to the environment because, since 2000, paint removal activities have been conducted using full containment. At the VLF transformer houses associated with Site 4 (evaluated separately in the VLF Transformer House Technical Memorandum, Resolution 2018a), caulking material containing PCBs was used along the roof of these buildings, and PCBs leached from the caulk as it weathered and entered the soil surrounding the outside perimeter of the transformer houses. PCB contamination around these buildings is limited to surface soil (0 to 2 feet bgs), and PCB concentrations decrease with distance away from the VLF transformer houses.

During the RI and previous investigations, soil samples, freshwater and marine sediment samples, and marine (shellfish) and terrestrial (earthworms) biota samples were collected to determine the nature and extent of paint chip-related chemical contamination in soil, streams, wetlands, and coastal areas at Site 4.

Chemicals detected at concentrations greater than project screening levels and background concentrations at Site 4 included PCBs in soil, freshwater sediment, terrestrial biota (earthworms), and marine biota (shellfish) and metals (antimony, cadmium, chromium, cobalt, lead, selenium, thallium, and zinc) in soil, freshwater and marine sediment, and terrestrial and marine biota. Elevated concentrations were generally detected in the uppermost 2 to 6 inches of soil. The top 2 to 4 inches of soil has the greatest density of paint chips/particles. Concentrations of metals and Aroclor-1254 vary significantly across the site, but in general, PCB and metals concentrations decrease significantly beyond 75 feet (150-foot diameter) from the bases of the towers. Subsurface soil and groundwater were not evaluated because of the nature of paint

9 September 2019

FIGURE 2-1. CONCEPTUAL SITE MODEL

10 September 2019 chip depositions and presence of a mesh copper grounding mat, necessary for operation of the VLF transmitter, extending across the VLF Peninsula at approximately 2 to 3 feet bgs.

PCBs are non-polar hydrocarbons that have a strong affinity for sediment and suspended solid particles.

Metals are highly persistent and when released to the environment also generally adsorb to the soil matrix and remain bound to particulate matter. PCBs and metals are considered persistent in the environment.

PCBs are only slightly volatile and have very low aqueous solubilities. PCBs and metals tend to migrate from source areas via bulk movement processes (e.g., transport by wind erosion or with suspended particulates in water) and, if leaching from soil to groundwater occurs, it usually results in transportation over relatively short distances.

2.6 CURRENT AND POTENTIAL FUTURE SITE AND RESOURCE USES

The NSA Cutler facility is situated on approximately 2,860 acres along the Gulf of Maine coast in Cutler, Maine. The VLF Area is bordered by Machias Bay to the west and Little Machias Bay to the east. Holmes Bay lies west of the Former Administration and Housing Area and High Frequency Area. The area surrounding the NAS Cutler facility is mostly rural, with some residential development in the vicinity of the base. Access to the VLF Area is restricted by base security and can be gained only through a security checkpoint located in the northeastern portion of the base along Ridge Road. The entrance to the facility is accessed via Ridge Road located approximately 1.5 miles west of Route 191 in Cutler, Maine. Although there are no physical access restrictions around the VLF Peninsula (other than water), human access to the operational array is prohibited and is restricted to base personnel performing operation and maintenance. Currently, there is no residential or recreational use on the base.

There are seven water production wells at NSA Cutler, five of which are used as water sources for the facility. Two of the wells located at the Power Plant are no longer in use due to saltwater intrusion. Three of the wells are located on the VLF Peninsula at Buildings 100, 132-135, and the Power Plant. Two of the wells are located in the area north of the VLF Peninsula at the High Frequency Transmitter Building 400 and Administrative and Housing Area. The only well used as a drinking water source services Building 132-135 and is regulated by the Maine Department of Health and Human Services (Tetra Tech, 2007).

2.7 SUMMARY OF POTENTIAL RISKS

The baseline risk assessments, including the human health risk assessment (HHRA) and ecological risk assessment (ERA), estimate the potential human and ecological risks posed by the site if no additional actions were taken to address potential contamination. It provides the basis for taking action and identifies the contaminants and exposure pathways that need to be addressed by the remedial action. The HHRA and ERA were conducted as part of the RI (Resolution Consultants, 2016) and are summarized below.

2.7.1 Summary of Human Health Risk

The quantitative HHRA was conducted using chemical concentrations detected in soil, sediment, and marine (shellfish) and terrestrial (earthworms) biota samples collected during the RI and previous sampling events. Key steps in the risk assessment process included identification of chemicals of potential concern (COPCs), exposure assessment, toxicity assessment, and risk characterization. For purposes of the HHRA, soil and sediment collected from 0 to 4 inches bgs were identified as surface soil and surface sediment, respectively, and soil and sediment collected from 4 to 12 inches bgs was identified as near-surface soil and near-surface sediment, respectively Soil and sediment samples collected from 2 to 6 inches bgs were identified as near surface because this interval does not include the most surficial soils, and lead samples collected from 0 to 12 inches bgs were considered surface soil in the HHRA.

The HHRA evaluated surface and near-surface soil within 0.5-acre exposure units for all receptors to represent exposure to soil in only certain areas of the site rather than to soil across the entire site. For a recreational user scenario, in addition to the evaluation of surface and near-surface soil within each soil exposure unit, surface and near-surface soils were also evaluated on a site-wide basis to represent a potential hiker exposure scenario in which receptors are not confined to one specific area of the site.

Identification of COPCs

COPCs for soil were selected for quantitative evaluation based on comparisons of maximum detected concentrations to United States Environmental Protection Agency (EPA) Regional Screening Levels (RSLs)

11 September 2019 and facility-specific background levels (Battelle, 2005). Residential soil RSLs were used for selection of soil and sediment COPCs for the residential and recreational scenarios, and industrial soil RSLs were used to select COPCs for on-site industrial and construction worker scenarios. Maximum shellfish tissue sample concentrations were compared to RSLs for fish tissue calculated using the EPA RSL Calculator (2015).

Default exposure inputs provided in the calculator were used in conjunction with a fish ingestion rate of 54,000 mg/kg. The RSLs used for soil, sediment, and shellfish COPC selection correspond to Hazard Quotients (HQs) of 0.1 for non-carcinogens and incremental lifetime cancer risks (ILCRs) of 1x10-6 for carcinogens.

EPCs are the concentrations used in the risk assessment to estimate exposure and risk from each COPC.

The composite sampling used during the RI resulted in smaller sample sizes per exposure unit than what is recommended for use of EPA’s ProUCL Software (2013); therefore, the incremental sampling methodology (ISM) calculator provided in the Interstate Technology Regulatory Council ISM guidance (2012) was used to calculate the 95-percent upper confidence limit (UCL) on the arithmetic mean for each COPCs in soil within each EU. ISM was not used to collect samples at Site 4, but the ISM calculator is designed to calculate UCLs for data sets with very few samples. Therefore, this method for calculating UCLs for a small number of composite samples (rather than incrementally collected samples) was considered appropriate for calculating soil UCLs for the Site 4 HHRA.

During the site-wide evaluation conducted for soil (recreational hiker scenario), sediment, and shellfish tissue, for data sets other than lead with at least 10 samples and six detections, 95-percent UCLs, calculated using EPA’s Pro-UCL, Version 4.1.01, software, were used as EPCs for Site 4 COPCs. For data sets with less than 10 samples and six detections and in cases where the 95-percent UCL was greater than the maximum concentration, maximum detected concentrations were used as EPCs for the reasonable maximum exposure (RME) scenario, and arithmetic means were used as the EPCs for the central tendency exposure (CTE) scenario. The RME scenario assumes the maximum level of human exposure that could reasonably be expected to occur, and the CTE scenario assumes a median or average level of human exposure. For lead, in most cases, EPCs were equal to the arithmetic mean concentration within the exposure point, in accordance with EPA guidance (2003 and 2007). In some instances, lead EPCs were derived based on a subset of data within the area in which the COPC selection was based. In these cases, results indicated a localized area where lead would require further evaluation via lead modeling, and in these instances, EPCs are equal to individual sample results.

Exposure Assessment

During the exposure assessment, current and potential future exposure pathways through which humans might come into contact with the COPCs identified in the previous step were evaluated. The results of the exposure assessment for Site 4 were used to refine the conceptual site model, which identifies potential contaminant sources, contaminant release mechanisms, transport routes, and receptors under current and future land use scenarios (see Figure 2-1). Potential exposure routes for soil at the site include dermal contact, incidental ingestion, and inhalation of airborne particles (fugitive dust) from soil. Potential exposure routes for sediment include dermal contact and incidental ingestion, and potential exposure routes for shellfish include ingestion. As stated above, groundwater was not evaluated based on the presence of the copper grounding mat and surficial nature of the chemical releases. The HHRA considered receptor exposure under non-residential land use by construction workers, industrial workers, recreational users and trespassers, off-site recreational fishermen, and hypothetical future residents. The current and future exposure pathways evaluated in the HHRA for Site 4 are summarized in Table 2-2.

TABLE 2-2. RECEPTORS AND EXPOSURE ROUTES EVALUATED IN THE HHRA

RECEPTOR EXPOSURE ROUTE

Construction Workers (current and future land use)

Soil incidental ingestion (surface and near-surface) Soil dermal contact (surface and near-surface) Inhalation of airborne particles from soil (surface and near-surface) Freshwater sediment incidental ingestion (surface and near-surface) Freshwater sediment dermal contact (surface and near-surface)

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TABLE 2-2. RECEPTORS AND EXPOSURE ROUTES EVALUATED IN THE HHRA

RECEPTOR EXPOSURE ROUTE

Child and Adult Recreational Users/Trespassers (current and future land use)

Soil incidental ingestion (surface and near-surface) Soil dermal contact (surface and near-surface) Inhalation of airborne particles from soil (surface and near-surface) Freshwater sediment incidental ingestion (surface and near-surface) Freshwater sediment dermal contact (surface and near-surface)

Off-Site Recreational Fisherman (current and future land use)

Marine sediment incidental ingestion (surface and near-surface) Marine sediment dermal contact (surface and near-surface) Shellfish tissue ingestion

Industrial Worker (future land use)

Soil incidental ingestion (surface and near-surface) Soil dermal contact (surface and near-surface) Inhalation of airborne particles from soil (surface and near-surface) Freshwater sediment incidental ingestion (surface and near-surface) Freshwater sediment dermal contact (surface and near-surface)

Child and Adult Residents (hypothetical future land use)

Soil incidental ingestion (surface and near-surface) Soil dermal contact (surface and near-surface) Inhalation of airborne particles from soil (surface and near-surface) Freshwater sediment incidental ingestion (surface and near-surface) Freshwater sediment dermal contact (surface and near-surface)

Toxicity Assessment

The toxicity assessment involves identifying the types of adverse health effects caused by exposure to site COPCs and determining the relationship between the magnitude of exposure and the severity of adverse effects (i.e., dose-response relationship) for each COPC. Based on the quantitative dose-response relationships determined, toxicity values for both cancer (cancer slope factor [CSF]) and non-cancer (reference dose [RfD]) effects were derived and used to estimate the potential for adverse effects.

Risk Characterization

During the risk characterization, the outputs of the exposure and toxicity assessments are combined to characterize the baseline risk (cancer risks and non-cancer hazards) at a site if no further action is taken to address chemical contamination. Potential cancer risks and non-cancer hazards were calculated based on RME and CTE assumptions. As stated above, the RME scenario assumes the maximum level of human exposure that could reasonably be expected to occur, and the CTE scenario assumes a median or average level of human exposure. Risk management decisions for Site 4 were based on the results of the HHRA assuming the RME scenario.

For carcinogens, risks are generally expressed as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to the carcinogen, expressed as an ILCR. MEDEP’s target risk guidance value for site-related exposures is 1 x 10-5. For non-carcinogens, the risk to human health is expressed as a Hazard Index (HI). An HI greater than 1.0 suggests that adverse health effects are possible.

Table 2-3 provides a summary of the calculated RME cancer risks and non-cancer hazards for Site 4.

Under the RME scenario, unacceptable cancer risks and/or non-cancer hazards (exceeding the MEDEP risk guidance value of 1 x 10-5 or HI of 1, respectively) were identified for construction workers, recreational users, industrial workers, and hypothetical future residents exposed to surface and near-surface soil and sediment at Site 4. The only final risk drivers were total PCBs. Total chromium results, initially evaluated conservatively in the risk assessment as 100 percent hexavalent chromium, were further evaluated with respect to the oral cancer toxicity value, in accordance with MEDEP guidance, and total chromium was not selected as a risk driver for the site.

Because published toxicity criteria are not available for lead, exposure to lead in soil, sediment, and shellfish tissue was evaluated using the Integrated Exposure Uptake Biokinetic (IEUBK) Model and Technical Review Workgroup Adult Lead Model (ALM) for residential and non-residential exposure scenarios, respectively, as recommended by EPA. The blood-lead concentration of a receptor is considered a key

13 September 2019 indicator of the potential for adverse health effects from lead contamination. The IEUBK Model and ALM calculate the probability of a receptor’s blood-lead level exceeding 10 μg/dL, the minimum concentration considered to be a “concern.” In addition, the USEPA goal is to limit the risk (i.e., probability) of exceeding a 10 μg/dL blood-lead concentration to 5 percent of the population. The IEUBK Model for lead is designed to estimate blood levels of lead in children (under 7 years of age), and using the ALM, adult exposure to lead in soil is addressed by evaluating the relationship between site soil lead concentrations and blood-lead concentrations in the developing fetuses of adult women. EPA’s model for Assessing Intermittent or Variable Exposures at Lead Sites (2003c) was used to derive screening levels for lead protective of a current/future recreational user (adult/child) exposure. Lead modeling results indicated unacceptable risks for construction workers exposed to surface soil in Area S-0 (South Helix House) and for hypothetical future residents exposed to surface soil in Area N-0 (North Helix House) and S-0. Lead results were less than target levels for all other receptors.

Unacceptable risks are as follows:

Calculated lead risks were greater than EPA benchmarks for current and future construction workers and hypothetical future residents exposed to combined surface and near-surface soil (0 to 12 inches bgs) in the South Helix House main tower area (S-0) and for hypothetical future residents exposed to near-surface soil (0 to 4 inches bgs) in the North Helix House main tower area (N-0).

Estimated cancer risks were greater than EPA’s target risk range of 1 x 10-4 to 1 x 10-6 for current and future recreational users, future industrial workers, and hypothetical future residents exposed to PCBs site wide (North Helix House, South Helix House, and Northern and Southern Tower Arrays). Risks were unacceptable for recreational users and residents in combined surface and near-surface soil (0 to 12 inches bgs) and for industrial users in surface soil (0 to 4 inches) only.

TABLE 2-3. SUMMARY OF RME CANCER RISKS AND HAZARD INDICES

RECEPTOR AND

MEDIUM

CANCER RISKS NON-CANCER HAZARDS

ILCRS

PRIMARY RISK

CONTRIBUTORS HIS

PRIMARY

HAZARD

CONTRIBUTORS

Construction Worker

Surface Soil + Surface Freshwater

Sediment

9 x 10-8 to 4 x 10-5

Chromium* 0.02 to 0.8 --

Near-Surface Soil + Surface Freshwater

Sediment

5 x 10-8 to 2 x 10-5 Chromium* 0.06 to 0.3 --

Recreational Users

(Adult/Child)

Surface Soil + Surface Freshwater

Sediment

2 x 10-5 to 3 x 10-4

PCBs and Chromium*

0.3 to 3 PCBs

Near-Surface Soil + Surface Freshwater

Sediment

2 x 10-5 to 2 x 10-4

PCBs and Chromium*

1 to 2 PCBs

Industrial Workers

Surface Soil + Surface Freshwater

Sediment

7 x 10-7 to 4 x 10-5

PCBs and Chromium*

0.01 to 0.5 --

Near-Surface Soil + Surface Freshwater

Sediment

4 x 10-7 to 2 x 10-5 Chromium* 0.04 to 0.1 --

On-Site Residents

(Adult/Child)

Surface Soil + Surface Freshwater

Sediment

2 x 10-5 to 5 x 10-4

PCBs and Chromium*

0.04 to 0.1

Near-Surface Soil + Surface Freshwater

Sediment

4 x 10-7 to 2 x 10-5

PCBs and Chromium*

0.04 to 0.1

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TABLE 2-3. SUMMARY OF RME CANCER RISKS AND HAZARD INDICES

RECEPTOR AND

MEDIUM

CANCER RISKS NON-CANCER HAZARDS

ILCRS

PRIMARY RISK

CONTRIBUTORS HIS

PRIMARY

HAZARD

CONTRIBUTORS

Off-Site Recreational Fisherman

Surface Marine Sediment +

Calm/Mussel Tissue 1 x 10-7 -- 1 --

Near-Surface Marine Sediment +

Calm/Mussel Tissue 2 x 10-7 -- 1 --

Ranges of ILCRs and HIs are for the 61 exposure units evaluated during the Site 4 HHRA. For recreational receptors, a site-wide hiker scenario was also evaluated.

-- No primary risk or hazard contributors because risk or hazard is acceptable.

* Total chromium results, initially evaluated conservatively in the risk assessment as 100 percent hexavalent chromium, were further evaluated, and total chromium was not selected as a risk driver for the site.

Lead risks were evaluated separately, and lead risk results are discussed above but not included in this table.

Sources of uncertainty in the HHRA for Site 4 included those typically associated with risk assessment estimates (Resolution Consultants, 2016).

Based on the results of the HHRA, the following RME risks were identified that require a remedial action at Site 4:

Unacceptable risks to and hypothetical future residents exposed to PCBs and lead in surface soil.

Unacceptable risks to on-site recreational users/trespassers exposed to PCBs in surface soil.

Unacceptable risks to construction workers exposed to lead in surface soil.

Unacceptable risks to industrial workers exposed to PCBs in surface soil.

2.7.2 Summary of Ecological Risk

An ERA consisting of Steps 1, 2 and 3a of the Navy’s ERA process was completed for Site 4 in accordance with Navy policy and EPA guidance, using chemical concentrations detected in Site 4 surface soil, marine and freshwater sediment, and earthworm and shellfish tissue collected between 2004 and 2011

Based on the results of the Site 4 ERA, it was determined that there may be potential risks to small insectivorous birds and mammals exposed to PCBs and lead in surface and near-surface soil in the South Helix House area. For all other ecological receptors evaluated, it was determined that no further evaluation of risk is warranted. Zinc was initially identified as an ecological COC for small insectivorous birds exposed to soil in several areas of the site. However, as part of the FS, re-evaluation of the regression model used to estimate earthworm tissue concentrations indicated that zinc concentrations in earthworms had been overestimated in the RI ERA. Based on the updated modeling, zinc does not pose an unacceptable risk to ecological receptors and is not identified as a COC for ecological receptors.

2.7.3 Basis for Action

As a result of past activities at Site 4, total PCBs and lead are present in soil at concentrations associated with unacceptable risks. Because unacceptable risks exist at the site under current and planned future land uses, a response action is necessary to protect human health from actual or threatened releases of hazardous substances into the environment that may present an imminent and substantial endangerment to public health or welfare.

As agreed to by the Navy and MEDEP, remediation at Site 4 will be conducted to meet human health standards, and additional ecological evaluation will be conducted after remediation to determine whether any indicator species are impacted. Post-excavation concentrations of total PCB and lead will be compared to the ecological preliminary remediation goals (PRGs) developed during the FS of 12 mg/kg and

15 September 2019

353 mg/kg, respectively. If remaining total PCB and lead concentrations at the site are less than the ecological PRGs, remediation of the site will also be deemed acceptable for the protection of ecological receptors.

2.8 REMEDIAL ACTION OBJECTIVE

RAOs are medium-specific goals that define the objective of conducting remedial actions to protect human health and the environment. RAOs provide a general description of what the cleanup will accomplish and typically serve as the design basis for the remedial alternatives described in Section 2.9.