Record of Decision (Rod) Site 2B

RECORD OF DECISION SITE 2B - AREA A WETLAND NAVAL SUBMARINE BASE - NEW LONDON, GROTON, CONNECTICUT NSB – New London OU12, Area A Wetland – Site 2B ROD 1.0 DECLARATION 1.1 SITE NAME AND LOCATION Naval Submarine Base-New London (NSB-NLON) EPA ID No. CTD980906515 Operable Unit (OU) 12 Area A Wetland - Site 2B Groton, Connecticut 1.2 STATEMENT OF BASIS AND PURPOSE This Record of Decision (ROD) presents the Selected Remedy for sediment at Area A Wetland - Site 2B, OU12 (see Figure 1-1), which was chosen by the Navy and United States Environmental Protection Agency (EPA) in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), 42 United States Code (USC) §9601 et seq., as amended by the Superfund Amendments and Reauthorization Act (SARA), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal Regulations (CFR) Part 300 et seq., as amended. This decision is based on information contained in the Administrative Record for the site. The Connecticut Department of Environmental Protection (CTDEP) concurs with the Selected Remedy (see Appendix A). FIGURE 1-1. SITE LOCATION MAP 1 August 2010 NSB – New London OU12, Area A Wetland – Site 2B ROD 1.3 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. A CERCLA action is required because concentrations of polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, and metals in sediment pose unacceptable risk to current and future to ecological receptors (i.e., sediment invertebrates). Groundwater at Area A Wetland – Site 2B was addressed as part of the Basewide Groundwater Operable Unit 9. As documented in the OU9 ROD signed in September 2008, groundwater monitoring at Site 2B will continue as required by the Area A Landfill, OU1 ROD. Surface water at the Area A Wetland is currently monitored under the Area A Landfill long-term monitoring program (OU1). Surface water is not considered further for this OU12 ROD because previous evaluations of surface water data concluded that potential risks to terrestrial and aquatic receptors were not great enough to warrant further evaluation of these receptors at the Area A Wetland. Also, risks to human receptors (construction workers and older child trespassers) from exposure to chemicals in surface water were acceptable. 1.4 DESCRIPTION OF SELECTED REMEDY The major components of the Selected Remedy for Site 2B include the following: Excavation of contaminated sediment greater than remediation goals (RGs) and transport of sediment off-site for proper disposal. Note that the preliminary remediation goals (PRGs) that were developed in the RI Update/FS for the Area A Wetland are referred to and used as RGs in this ROD. Restoration of excavated areas to pre-existing elevations with clean organic soil. Seeding the restored area to establish native wetland vegetation. Monitoring of the area to ensure that the native wetland vegetation has been established. Land use controls (LUCs) to prevent future residential use of the Area A Wetland. The Selected Remedy eliminates unacceptable ecological risk by removing all sediment associated with unacceptable risk. The cleanup of Site 2B will not adversely impact the current and reasonably anticipated future land use of the site as a wetland. The Selected Remedy is expected to achieve substantial long-term risk reduction and allow the property to be used for the reasonably anticipated future land use of the site as a wetland. This ROD documents the final remedial action for Site 2B and does not include or affect any other sites at the facility. Implementation of this remedy is consistent with current use and the overall cleanup strategy for NSB-NLON to cleanup sites to achieve compliance with CERCLA. Compliance with CERCLA includes achieving Applicable or Relevant and Appropriate Requirements (ARARs) identified in Appendix E of this ROD. 1.5 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. The Selected Remedy would not achieve reduction in contaminant toxicity, mobility, or volume through treatment, except to the extent water from the dewatering process requires treatment or sediment stabilization reduces the mobility of contaminant within the treated sediment. Based on the type of contamination at the Area A Wetland (PAHs, PCBs, pesticides, and metals), the silt and fines content of the sediment, and the large volume of contaminated 2 August 2010 NSB – New London OU12, Area A Wetland – Site 2B ROD sediment, the Navy concluded that it was impracticable to excavate and treat the chemicals of concern in a cost-effective manner. Because the human health assessment conducted for the Area A Wetland did not include a residential scenario, LUCs would be required for the entire wetland until it is demonstrated that the entire wetland, or a portion of the wetland, presents acceptable residential risk from contaminants in sediment. At that time, the LUCs can be removed for the portion of the wetland where risks to residential receptors are found to be acceptable. Because contamination will be left in place that may not allow for unrestricted use, 5-year reviews would be required under this alternative. As part of this decision document the Navy finds under the Section 404 of the federal Clean Water Act that the remedy required in this ROD is the least environmentally damaging practicable alternative to protecting wetland resources because all CERCLA-related contamination detected at concentrations exceeding RGs will be removed from the site, wetlands will be restored in place, invasive species will be controlled, and LUCs will be established to prevent residential development within the wetland area. USEPA finds, as documented on page 6 of this ROD, under the Toxic Substances Control Act (TSCA) that the RG of 532 ppb for total PCBs used for the remedy will not pose an unreasonable risk of injury to human health or the environment. 1.6 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 NSB-NLON. TABLE 1-1. ROD DATA CERTIFICATION CHECKLIST DATA LOCATION IN ROD Chemicals of concern (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 current and Section 2.6 potential future beneficial uses of groundwater used in the risk assessment Potential land and groundwater uses that will be available at the site as a result of the Section 2.12.3 Selected Remedy Estimated capital, operating and maintenance (O&M), and total net present worth (NPW) costs; discount rate; and number of years over which the remedy costs are Appendix F projected Key factors that led to the selection of the remedy Section 2.12.1 If contamination posing an unacceptable risk to human health or the environment is discovered after execution of this ROD and is shown to be a result of Navy activities, the Navy will undertake the necessary actions to ensure continued protection of human health and the environment. 1.7 AUTHORIZING SIGNATURES The signatures provided on the following pages validate the selection of the final remedy for sediment at OU12, Site 2B, by the Navy and EPA. CTDEP concurs with the Selected Remedy. 3 August 2010 NSB - New London OU12, Area A Wetland - Site 2B ROD Concur and recommend for implementation: Marc W. Denno USN Date Commanding Officer Naval Submarine Base - New London 4 August 201 0 ---------~--~~~~ .. ~.~.~~---.... -.. --.... -. NSB - New London OU12, Area A Wetland - Site 2B ROD EPA finds under the TSCA that the risk-based cleanup level for total PCBs in the Area A Wetland will not pose an unreasonable risk of injury to human health or the environment pursuant to 40 C.F.R. Section 761 .61 (c). Concur and recommend for implementation: James T. Owens, III, Director Date Office of Site Remediation and Restoration EPA Region 1 5 AugusI201 0 NSB – New London OU12, Area A Wetland – Site 2B ROD 2.0 DECISION SUMMARY 2.1 SITE NAME, LOCATION, AND BRIEF DESCRIPTION NSB-NLON, EPA ID number CTD980906515, is located in southeastern Connecticut in the Towns of Ledyard and Groton and is situated on the eastern bank of the Thames River, approximately 6 miles north of Long Island Sound. It is bordered to the east by Connecticut Route 12, to the south by Crystal Lake Road, and to the west by the Thames River. NSB-NLON currently provides base command for Naval submarine activities in the Atlantic Ocean. It also provides housing for Navy personnel and their families and supports submarine training facilities, military offices, medical facilities, and facilities for the submarine maintenance, repair, and overhaul. The Area A Wetland is approximately 26 acres. The Area A Weapons Center (Site 20, OU8) is located northwest of the Area A Wetland, and the Area A Landfill (Site 2A, OU1) is adjacent to the western boundary of the Area A Wetland. Water from the wetland ultimately drains to a channel located in the western portion of the landfill and then discharges through an earthen dike via four 24-inch metal culverts to the Area A Downstream Watercourses (Site 3, OU3).

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