Andersen Air Force Base

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

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.

Site Studies

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.

Site Studies

Basewide Groundwater: All areas of suspected groundwater contamination have been identified. There are no drinking water wells located in areas with contamination.

Site Studies

Cleanup Complete

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 will be amending the ROD in 2013 to propose 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 will implement institutional controls prohibiting the pumping of groundwater in the deep plume area.

Cleanup Complete

Site Studies

Cleanup Complete

Harmon Annex: This site covers 1400 acres and is located above Tumon Bay. The site has been cleaned to unrestricted reuse levels.

Remedy Selected

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 is currently cleaning 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.