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A view of Downtown Adak, overlooking Sweeper Cove

Environmental restoration projects began on Adak under the Navy Assessment and Control of Installation Pollutants program with an initial assessment study (IAS) in 1986. The IAS identified 32 sites on Adak that could be a potential threat to human health and the environment. In 1988, site inspections were conducted at areas identified in the IAS. In 1989, a RCRA facility assessment (RFA) was completed by EPA under the RCRA corrective action program. Adak was proposed for the U.S. Environmental Protection Agency’s (EPA) National Priorities List in October 1992 and it was officially placed on the NPL in May 1994.

As a result of the RFA, preliminary source evaluations (PSEs) were conducted between 1993 and 1996 for a majority of the CERCLA sites initially identified under the IAS. The PSE process was a risk-based screening approach endorsed by EPA and ADEC to determine which potentially hazardous source areas posed a human health and ecological risk. Fifty-eight sites identified by the PSE process as requiring additional evaluation were included in the basewide remedial investigation and feasibility study (RI/FS). The former base was divided into two operable units, OU A and OU B. OU A includes 58 CERCLA sites and 128 petroleum sites covered by SAERA. Sites within OU A are categorized as either petroleum sites, CERCLA sites, or landfill sites. Some sites are considered both petroleum and CERCLA sites due to the presence of both petroleum and CERCLA regulated substances in soil and or groundwater. Petroleum sites on Adak are regulated under 18 AAC 75. CERCLA expressly excludes petroleum from its definition of hazardous substances (Section 101(14)), and therefore petroleum is not regulated under CERCLA. Instead, petroleum releases on Adak are regulated solely by the State of Alaska under 18 AAC 75. Issues regarding ordnance explosives are being addressed under OU B.

The RI/FS for OU A included development of conceptual site models to assess potential exposure pathways and identify potential risks to human health and the environment. The final RI/FS for OU A was published in September 1997. The purpose of the RI/FS was to assess site conditions and evaluate remedial alternatives to the extent necessary to select remedial actions, or remedies, for the CERCLA sites. Following preparation of the RI/FS report, a Proposed Plan for OU A was released to the public in January 1998. The Proposed Plan described the preferred alternatives for remediation of the sites investigated in the RI/FS. Public comment was solicited and with that input, remedial actions were selected for the sites. These remedy selections are presented in the Operable Unit A Record of Decision (OU A ROD), which identifies the decisions made by the Navy, the U.S. Environmental Protection Agency (EPA), and the Alaska Department of Environmental Conservation (ADEC) concerning CERCLA site remediation. The OU A ROD was signed by the Navy on October 14, 1999, by EPA on March 30, 2000, and by ADEC on April 13, 2000.

The OU A ROD presents the remedial actions for the 58 CERCLA sites on land, as well as downgradient groundwater and aquatic sites. Table 1 lists the cleanup remedies selected in the OU A ROD for each of the CERCLA sites evaluated in the RI/FS. Table 2 provides the institutional controls and engineering requirements for each of the sites, including petroleum sites.

The major components of the CERCLA site remedies in the OU A ROD are being implemented on a site-by-site basis as appropriate. They include the following:

Excavation and treatment by thermal desorption of contaminated sediments and soils
Recycling of treated sediment and soils as daily cover material at the on-island Roberts Landfill
Placement of a soil cover over SWMU 4, South Davis Landfill
Institutional controls to protect against exposure to hazardous substances left on site (ongoing)

The OU A ROD states that no further action is required at 33 CERCLA sites (including 2 water bodies) and 82 petroleum sites. These are summarized in Table 3. An amendment to SAERA, signed in February 2002, lists the specific sites and the schedule for completion of remedial decision documents as appropriate for these sites. As provided in the OU A ROD, to the extent that the sites under SAERA require remediation in the future, cleanup decisions will be made in accordance with 18 AAC 75.325 through 18 AAC 75.390. Since the completion of the ROD for OU A, remedial actions have been performed at 10 petroleum release sites designated for limited soil removal.

During the 1999 field season, work was conducted at both South Sweeper Creek and at two ponds at the SWMU 17 Power Plant 3 Area site. Sediments were removed at both sites and dewatered. The sediments were treated by thermal desorption. Once these sediments were treated, they were moved to Roberts Landfill to be used as cover. The areas from which the sediments were removed were regraded; SWMU 17 was also regraded. Implementation of institutional controls is ongoing.

An interim action ROD for SWMU 11, Palisades Landfill, and SWMU 13, Metals Landfill, was developed in 1995 to address the potential for releases of hazardous substances that may have presented an imminent and substantial endangerment to public health, welfare, and/or the environment. The remedies selected in the decision document were developed in accordance with CERCLA and the National Oil and Hazardous Substances Pollution Contingency Plan. Interim actions included construction of landfill caps, construction of small interceptor ditches on the uphill side of the landfills, rerouting of Palisades Creek, establishing vegetation on the new cap, inspection and removal of material that could adversely affect the marine environment, installation of monitoring wells and initiation of a monitoring program, and implementation of institutional controls. The interim action ROD for SWMUs 11 and 13, Palisades and Metals Landfills, was signed in March 1995 (Navy, Alaska DEC, and USEPA 1995).

In 1997, a risk assessment was completed for Kuluk Bay to quantitatively evaluate the potential human and ecological risks from contaminants in marine sediment, surface water, and biota. This risk assessment was also used to evaluate the suitability of the interim remedial actions completed in 1996 at SWMU 11, Palisades Landfill and in 1997 at SWMU 13, Metals Landfill. Human health COPCs for SWMU 11, Palisades Landfill in sediment is total lead. Surface water human health COPCs are antimony and cadmium. Mussel tissue human health COPCs are arsenic, cadmium, copper, lead, and selenium. Ecological COPCs for SWMU 11, Palisades Landfill sediment are total polychlorinated biphenyls (PCBs), endrin ketone, antimony, cobalt, and vanadium. Surface water ecological COPCs are barium and cadmium; mussel tissue COPCs are Aroclor 1254, arsenic, cadmium, copper, lead, selenium. The capping, monitoring, and institutional control actions completed under the interim action ROD for SWMUs 11 and 13, Palisades and Metals Landfills, were evaluated and determined to be protective during the OU A ROD process and in the OU A ROD (Section 4.3) interim actions was selected as a final remedy.

SWMUs 18/19, White Alice Landfill, and SWMU 25, Roberts Landfill, were operated on Adak Island under Alaska DEC solid waste regulations (18 AAC 60). Analytical results from Roberts Landfill have shown exceedances of chromium, copper, and lead, when compared to Alaska Water Quality Standards 18 AAC 70. Analytical results from White Alice Landfill for volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), pesticides, PCBs, and total inorganics were compared to Alaska Water Quality Standards 18 AAC 70 and showed no exceedances. White Alice Landfill was closed and covered in compliance with State of Alaska regulations in 1997. Prior to closure at the SWMU 25 Roberts Landfill, in 1997, a low-permeability soil cover was placed over the landfill, grading and contouring completed, access restrictions implemented, surface water/erosion controls installed, a vegetative cover placed, and adjacent bunkers that were filled with asbestos materials secured.

Specific remedial action categories for the petroleum sites included limited soil removal, limited groundwater monitoring, monitored natural attenuation, free-product recovery as an interim measure followed by remedy selection using an focused feasibility study (FFS) process, and remediation of a small site as part of a larger site cleanup (U.S. Navy, Alaska DEC, USEPA 2000). Removal of free product at petroleum-release sites is considered an interim measure by the Alaska DEC, USEPA (18 AAC 75.330). Therefore, for 14 sites where free product is present on the groundwater surface, remedial alternatives are being evaluated using the FFS process, following completion of practicable product recovery (18 AAC 75.325). Product recovery was not completed to the ROD endpoint, but was stopped based upon practicable criteria (18 AAC 75.330) at 11 of the 14 sites, and the FFS was process initiated. Three sites have not met the numerical goals for monthly average recovery endpoints specified in the OU A ROD. These sites (NMCB, South of Runway 18-36 Area, and Tanker Shed) have a remedy evaluation in the FFS that addresses the need for further recovery. The status of several CERCLA and petroleum sites has subsequently changed based on results of post-ROD monitoring conducted from 1999 through 2002. NFA status was approved for four soil removal sites following the limited soil removal action. NFA status was recommended for 13 sites based on the results of the comprehensive monitoring program. The remaining number of petroleum sites assumed to require further action at this time is 29.