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The 76,000-acre Adak Naval Air Station (NAS) site is located on Adak Island, near the western end of the Aleutian Islands, Alaska. Between the early 1940s and 1997, NAS served as a key operations and supply location for United States military forces. Site activities during that time included disposal of hazardous substances on the island, including landfills, storage areas, drum disposal areas, spill sites and pits for waste oil and fire-fighting training. Some of these hazardous substances included petroleum, chlorinated solvents, batteries, transformer oils containing polychlorinated biphenyls (PCBs), and unexploded ordnance. These activities contaminated ground water, sediments and soil with hazardous chemicals. All site investigations are complete and remedy construction is nearing completion. Long-term monitoring is ongoing.

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What Has Been Done to Clean Up the Site?

Adak Island is a federally designated wilderness area, and is part of the Alaska Maritime National Wildlife Refuge. It was used for military operations from the early 1940s until it operationally closed on September 31, 2000. At this time, Navy operations consist solely for long-term maintenance of Superfund cleanups and final clearance of ordnance items.

Over a 40-year period, hazardous substances were disposed of in areas on the island, including landfills, storage areas, drum disposal areas, spill sites, and pits for waste oil and fire-fighting training. Petroleum, chlorinated solvents, batteries, transformer oils containing polychlorinated biphenyls (PCBs), and unexploded ordnance are some of the hazardous materials present at the site. Primary releases include: PCBs (over 2,000 gallons), unexploded ordnance (70,000 items located, not including ranges and offshore disposal), petroleum (1,000,000 gallons), solvents, and pesticides. A wide variety of marine mammals and birds inhabit the near-shore areas. Access to remote areas is allowed, but restrictions are necessary due to potential presence of unexploded ordnance. The island is subject to high winds and frequent storms.

The site is being addressed through federal actions.

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What Is the Current Site Status?

The site has been divided into three operable units (OUs): A, B-1 and B-2. OU-A addresses traditional hazardous waste and petroleum releases at the site. OUs B-1 and B-2 address unexploded ordnance. Remedy construction at OU-A is complete and the Navy is conducting long-term monitoring of the various remedies implemented. Remedy construction for OU B-1 is complete. OU B-2 addresses the remaining property that has not been transferred out of Navy control due to the presence of unexploded ordnance (UXO). The Navy is currently conducting a non-time-critical removal action for OU B-2.

Long-term remedies included capping of historic landfills; treating contaminated ground water; excavating and treating contaminated soils; clearance of UXO; long-term monitoring of sediments and landfill covers; and land use controls. Remedy construction began in 1996 and only ordnance removal remains to be completed.

Cleanup has also included more than 20 removal actions, or short-term cleanups, to address immediate threats to human health and the environment. These actions addressed polychlorinated biphenyl (PCB)-contaminated soils and sediments, buried drums, unexploded ordnance (UXO) and other releases.

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 for OU A and OU B-1 concluded that response actions at the site are in accordance with the remedy selected by EPA and that the remedy continues to be protective of human health and the environment. The Navy completed the fourth 5 Year Review in December 2016.

EPA placed the site on the Superfund program’s National Priorities List (NPL) in 1994.

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