Superfund Information Systems: Site Profile

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The Eielson Air Force Base site covers 19,780 acres in Fairbanks North Star Borough, located 24 miles southeast of Fairbanks, Alaska. The site contains both closed and active unlined landfills, shallow trenches where weathered tank sludge was buried, a drum storage area, and other disposal and spill areas. Site activities contaminated soil and groundwater with hazardous chemicals. Following cleanup, operation and maintenance activities and monitoring are ongoing.

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What Has Been Done to Clean Up the Site?

EPA has conducted several five-year reviews of the site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent review concluded that response actions at the site are in accordance with the remedy selected by EPA; however, EPA has deferred making a protectiveness statement until additional information can be obtained. Long-term protectiveness of the remedy requires additional work to further characterize the nature and extent of contamination and to determine if the risks presented warrant additional remedial action.

Eielson Air Force Base (AFB) is an active installation established in 1944. The mission of the base is to train and equip soldiers for close air support of ground troops in an arctic environment. Eielson AFB is located approximately 25 miles southeast of Fairbanks, Alaska. The base encompasses approximately 20,000 acres, most of which is undeveloped forests, wetlands, and ponds. Approximately 3,600 acres have been developed. The base is located on the Tanana River floodplain and the slopes of the Yukon-Tanana uplands.

Approximately 5,500 people live on base, with other personnel living in the nearby communities of North Pole, Salcha, and Moose Creek. The groundwater resources on base are used for drinking water and industrial, domestic, agricultural, and firefighting needs.

In November 1989, Eielson AFB was listed on the National Priorities List (NPL) of federal Superfund sites by the Environmental Protection Agency. In the 1994 Remedial Investigation and Feasibility Study for Eielson AFB, 66 source areas of possible contamination were found. These sites are evaluated through the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). In the 1995 Record of Decision, many of the potential sites were found not to pose an unacceptable risk to human health and the environment and were closed by EPA and ADEC (the five-year Record of Decision Review for 2003 describing this action is available on the Eielson website). Several sites were given a conditional closure and were placed under "institutional controls" to prevent people from being exposed to any remaining contamination.

Remediation activities occurred during the 1990's at many of the contaminated sites on Eielson AFB. Petroleum-contaminated soil was excavated and treated by landfarming. Soil caps were installed to prevent human exposure to contamination and limit the transport of contamination. Other sites had active remediation systems installed such as soil vapor extraction, bioventing, and free-product recovery wells.

At Garrison Slough, PCB contamination has impacted the sediments and fish. A portion of the PCB-contaminated sediments have been excavated, and the PCB contamination in fish tissue and sediments continue to be monitored. A fishing restriction is in place for Garrison Slough and physical fish gates restrict the passage of fish into and out of the contaminated area.

Currently, most of the sites are in a long-term monitoring program to ensure contaminant plumes are stable or decreasing and are not moving offsite or to drinking water wells. Several sites are still being treated by active remediation systems. Institutional controls, such as restriction of ground-water use in certain areas, fishing advisory, and a dig permitting process for construction activities, are in place at Eielson AFB to prevent exposure to any remaining contamination.

In the 1995 Record of Decision for Eielson AFB, 29 areas were divided into six Operable Units based on common characteristics or contaminants, and 31 other areas of contamination were evaluated through a source evaluation process (SER). The remaining contaminated sites are addressed through ADEC regulations.

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What Is the Current Site Status?

The site is being addressed in five long-term actions focused on cleanup of two fuel-contaminated areas, trichloroethylene spills, a drum burial area, landfills and a comprehensive evaluation of the entire site. The site’s long-term remedy included bioventing and soil vapor extraction (SVE) to treat fuel-contaminated source areas; institutional controls; site monitoring; excavation of contaminated soil; installation of a cap over the site’s largest historic landfill; and excavation and disposal of polychlorinated biphenyl (PCB)-contaminated soil and sediment from Garrison Slough. Remedy construction took place between 1993 and 1998. The Air Force, in conjunction with EPA and the Alaska Department of Environmental Conservation, continues to monitor ongoing cleanup actions and environmental conditions under an annual sitewide monitoring program.

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Activity and Use Limitations

At this site, activity and use limitations that EPA calls institutional controls are in place. Institutional controls play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use. They also guide human behavior. For instance, zoning restrictions prevent land uses – such as residential uses – that are not consistent with the level of cleanup.

For more background, see Institutional Controls.

Benzene: Xylene: Trichloroethylene: Toulene: PCBs:

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Sampling and Monitoring

Currently, most of the sites are in a long-term monitoring program to ensure contaminant plumes are stable or decreasing and are not moving offsite or to drinking water wells.

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