GEORGE AIR FORCE BASE
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The 5,347-acre George Air Force Base was established in World War II and closed in December 1992. Its mission was to support tactical fighter operations and provide training for air crews and maintenance personnel that mandated the use and disposal of hazardous and non-hazardous materials. Site investigations and long-term cleanup are ongoing.
What Has Been Done to Clean Up the Site?
EPA, the state and the U.S. Air Force signed a Federal Facilities Agreement (FFA) in October 1990 for cleaning up the base. The Air Force is the lead agency for site cleanup, with EPA and the State of California Lahontan RWQCB providing regulatory oversight through FFA Base Closure Team (BCT) procedures. The California Department of Toxic Substances Control (DTSC), formerly the California Department of Health Services, was part of the BCT until 1998 when they deferred roles and responsibilities to the RWQCB.
What Is the Current Site Status?
To better manage site investigations and cleanup, three operable units (OUs) were established for the site. OU-1 is the 600-acre trichloroethylene (TCE) groundwater plume in the Northeast base area and extends off base. OU-3 is the landfills and/or disposal sites with other various soil sites contaminated with volatile organic compounds (VOCs). OU-5 is a TCE soil contamination source column over the OU-1 groundwater plume, and also includes three former skeet ranges. OU-2 was pulled out of the Superfund process in 2005 for state oversight. OU-4 and OU-5 were created and later combined as OU-5. OU-4 was to document completed response actions for miscellaneous sites that dropped out from OU-2.
Initial Actions: In 1991, the Air Force began operating a pump-and-treat (PAT) system with air stripping for groundwater contaminated with TCE under OU-1's northeast base area that migrated off base. In early 1992, the Air Force started removing jet fuel (JP-4) free product at OU-2 using passive skimming technology, and supplemented soil vapor extraction (SVE) for removing VOCs from soils several years later. Remedial actions for various OU-3 sites started in the mid-1990s to remove VOCs from soil sites. A pilot SVE project in OU-5 addressed the TCE soil source column. Soils contaminated with metals were removed from the former skeet ranges.
OU-1 Northeast Base Area: The long-term remedy, selected in 1994, included PAT and access controls for the TCE groundwater plume beneath the northeast base area. The flushing approach pushed TCE to the edge of the upper aquifer where it is "temporarily stored." It could take many decades for it to migrate or cascade into the lower aquifer. The steep terrain in the area prevents any efficient monitoring or remedial actions. The PAT system has been shut down since 2003; it was making the TCE migration problem worse. The Air Force discovered that Site FT-082 was a TCE soil source column to the OU-1 groundwater plume and implemented SVE in 2007 as a pilot project. A remedy update for the OU-1 groundwater plume is under development.
OU-2 Jet Fuel Plume: OU-2 has over two million gallons of free product in groundwater. Passive skimming to remove the jet fuel from groundwater started in 1992 and monitored natural attenuation was the planned supplement remedy. The Air Force implemented SVE at EPA’s request to remove VOCs from the contaminated soil. In March 2005, the Air Force withdrew OU-2 from the Superfund process and converted the cleanup management process to a Corrective Action Plan (CAP). The state assumed the regulatory lead.
OU-3 Landfills, Disposal Areas and VOC Sites: Selected remedies included capping and access controls for landfills/disposal areas, and bioventing or SVE for VOC sites. Response actions for the landfills/disposal areas were completed. Actions for VOC sites are ongoing.
OU-4 documented “no further action” decisions for following sites: AOC 72/Current Skeet Range, AOC 73/Second Skeet Range, AOC 74/Original Skeet Range, AOC 75/Indoor Range, AOC76/Dozer Scar Area, AOC 77/Disturbed Area, AOC 78/Explosive Ordinance Disposal Training Area and AOC 80/Building 513. Skeet ranges were carried forward to OU-5. All other OU-4 sites were documented by the Air Force's 2008 No Further Response Action Report (NFRAP).
OU-5 is mainly an active SVE system at Sites FT-082 and SS-083 put in place to remove the high TCE levels in soil acting as a source column to OU-1’s TCE groundwater plume. OU-5 also includes three closed Skeet Ranges that are not expected to require further action (OT072, OT073 and OT074). The long-term remedy for these areas is under development.
The Lahontan Regional Water Quality Control Board (RWQCB) issued a Notice of Violation letter to the Air Force for dieldrin pesticide contamination in groundwater. The Air Force is only monitoring the pesticides in groundwater, as the levels are very low, but the plume has not been fully defined because of funding constraints. The Air Force would not consider EPA's request for an evaluation of the contamination extent in soil because the Air Force does not classify it as a CERCLA release to the environment; past general practices mandated the routine application of pesticides for termite control. The Air Force submitted another CAP document to address dieldrin; it is currently under State of California Lahontan Regional Water Quality Control Board (RWQCB) review.