Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Andersen Air Force Base
The Third Five Year Review Report was completed September 30, 2014.
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 02/07/92
Final Date: 10/14/92
Andersen Air Force Base (AAFB) is a 20,000-acre site located in the city of Yigo on the northern end of the island of Guam. Operational since 1940, AAFB's main purpose has been to provide support for Strategic Air Command operations. Hazardous substances associated with AAFB operations include solvents such as trichloroethane (TCE) and paint thinners; dry cleaning fluids and laundry products; fuels such as JP-4 and gasoline; pesticides; antifreeze; aircraft cleaning compounds; and polychlorinated biphenyls (PCBs). These substances are found in unlined landfills, drum storage and disposal areas, chemical storage areas, fire training areas, waste storage areas, the laundry facility, and industrial and flight line operations. AAFB is located in a karst limestone terrain. The Northern Guam Lens is a Sole Source Aquifer underlying the site. This aquifer supplies drinking water to at least 50 percent of the area residents; approximately 40,200 people draw drinking water from wells located within a four-mile radius of the site. Groundwater sampling by the Air Force indicates the presence of volatile organic compounds (VOCs) in the groundwater, though no water wells currently produce water from contaminated areas.
Contaminants and Risks
- Soil and Sludges
- Environmentally Sensitive Area
Groundwater sampling indicates the presence of VOCs including TCE, toluene, and tetrachloroethane. Surface areas, including landfills and scattered dumpsites, are contaminated with VOCs, PCBs, fuels, metals, and pesticides. There are 23 endangered species living near or on the base; portions of the base have been designated as a wildlife and marine preserve.
Who is Involved
The Air Force is the lead agency conducting the investigations and cleanup under oversight from EPA and the Guam EPA.
Investigation and Cleanup Activities
A working agreement between the Air Force, USEPA and Guam EPA called the Federal Facilities Agreement (FFA) was signed by all parties in 1993. This agreement provides the legal framework and schedule for the Air Force to perform remedial investigations and clean-up actions. The Air Force has installed dozens of monitoring wells into the drinking water aquifer, which is located several hundred feet below the ground surface. The groundwater investigation is complete in terms of identifying contaminant plumes.
Most soil contamination problems at Andersen are either the result of nearby industrial activity, or the result of materials being placed into scattered dump-sites. The areas with soil contamination are being investigated with a combination of surface soil sampling, borehole sampling, trenching, geophysical tools, and soil gas monitoring. The plan for most of the areas with soil contamination is to excavate and remove the problem. A few areas that are too big to excavate have or will have remedies proposed that involve capping the area and imposing land use controls to restrict access.
Initial Actions: Closure of the main base landfill in accordance with the requirements of the Resource Recovery and Restoration Act (RCRA) was completed in 1994. Landfill closure included the construction of a cover over the landfill.
Soil Contamination: Andersen AFB is working through sampling dozens of former dumpsites, spills and industrial area. As the investigations are completed, the sites are either proposed for cleanup or no action, as appropriate.
Basewide Groundwater: All areas of suspected groundwater contamination have been identified. There are no drinking water wells located in areas with contamination.
MARBO Annex: The MARBO Annex is located several miles south-southeast of the Main Base and covers 2,342 acres. The final remedy for soils has been completed by removing some hazardous soils off-island and removing some other less hazardous soils to the Main Base landfill. The groundwater is contaminated with trichloroethylene, which is a degreasing solvent. The Record of Decision signed in 1998 selected natural attenuation as the groundwater remedy. Long term monitoring has shown that the contaminants at the bottom of the aquifer, directly over the salt water zone, are not decreasing, so the Air Force and EPA amended the ROD in 2014 to invoke a waiver for technical impracticability. Because cleaning the aquifer directly over the salt water interface would cause upwelling of salt water into the drinking water portion of the aquifer, there is no practical way to implement a remedy. Thus, the ROD amendment implemented institutional controls prohibiting the pumping of groundwater in the deep plume area.
Harmon Annex: This site covers 1400 acres and is located above Tumon Bay. The site has been cleaned to unrestricted reuse levels.
Urunao Dumpsite: The Urunao Dumpsite is located over a cliff-line in the northwest portion of the base. Crashed aircraft were pushed off the runways over this cliff throughout WWII, the Korean War and Vietnam War. Portions of the dumpsite are located on private land. The Air Force cleaned the area with large cranes and appropriate earth moving equipment to physically remove those portions of the dumpsite that pose a health hazard. Cleanup was completed in 2009.
AAFB is participating in the Installation Restoration Program, a specially funded program established by the Department of Defense (DOD) to identify, investigate, and control the migration of hazardous contaminants at military and other DOD facilities.
Cleanup Results to Date
Immediate threats to the health and safety of the nearby population and environment have been reduced by the construction of the landfill cover. Contaminated groundwater is not available for consumption because no drinking water wells exist in areas of contamination. Areas with contaminated soil have either been cleaned up or access to those areas has been restricted.
Potentially Responsible Parties
Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.
Documents and Reports
Public Information Repositories
The public information repositories for the site are at the following locations:
RFK Memorial Library
Nieres M. Flores Library
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
P.O. Box 22439 GMF
Barrigada, Guam 96921
APA AP 96543-4007
After Hours (Emergency Response)