This website provides background information on the United States Department of the Navy (DON)’s Environmental Restoration Program (ERP) sites at Marine Corps Air Station (MCAS) Yuma. The overarching goal of the DON’s ERP is to protect human health and the environment from past hazardous waste practices and releases at DON and United States Marine Corps Installation Restoration Program (IRP), Munitions Response Program (MRP), and Underground Storage Tank (UST) program sites. The DON’s ERP at MCAS Yuma is managed by Naval Facilities Engineering Systems Command Southwest in San Diego, California.
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund, was established in 1980 to provide a mechanism for the United States Environmental Protection Agency (USEPA) to clean up sites contaminated with hazardous waste and prevent contamination of future sites by assigning liability to responsible parties. The MCAS Yuma IRP sites identified for the DON’s ERP have been or are currently being addressed under CERCLA.
The Superfund Amendments and Reauthorization Act (SARA) amended the CERCLA legislation in 1986. Among other changes, SARA established the Defense Environmental Restoration Program (DERP) which is managed by the Office of the Deputy Under-Secretary of Defense, Installations and Environment. The DERP cleans up hazardous substances, pollutants, contaminants, and military munitions remaining from past activities at military installations and formerly used defense sites.
To organize the CERCLA site characterization and cleanup process, MCAS Yuma was divided into two operable units (OUs). Within each OU are IR sites, identified at MCAS Yuma as areas and CERCLA areas of concern (CAOC). OU 1 is comprised of areas with potential groundwater and soil contamination deeper than 10 feet below ground surface. OU 2 is comprised of areas with potential soil contamination shallower than 10 feet below ground surface. The DON’s ERP has identified 26 areas and CAOCs at MCAS Yuma; five are currently undergoing investigations or remedial actions, two were transferred to the Arizona Department of Environmental Quality (ADEQ) UST program, and 19 have received no further action status. In addition, there are seven identified sites managed under the MRP, three of which are active, and four have received no further action status.
To investigate the potential for per- and polyfluoroalkyl substances (PFAS) at MCAS Yuma, compounds identified as “emerging contaminants” by the USEPA, a basewide preliminary assessment and site inspection for PFAS chemicals was conducted in 2019 and 2020. Based on site inspection results, PFAS-impacted areas were identified within closed sites CAOC 7 and 9, the OU 1 Area 1, and an area not previously investigated, now identified as Installation Restoration Site 20. The DON is currently conducting a PFAS remedial investigation for these four sites to further characterize the nature and extent of PFAS contamination.
The Marine Corps is the current landowner at MCAS Yuma, and the DON is working with the ADEQ, the USEPA, and the California Regional Water Quality Control Board, for some sites where groundwater plumes may be located or extend into California, to address issues related to past releases at each site by collecting and evaluating environmental data in accordance with the CERCLA process.
MCAS Yuma History
MCAS Yuma is approximately two miles southeast of the City of Yuma in the southwest corner of Arizona, bordering California and Mexico. The station occupies approximately 3,000 acres on the Yuma Mesa. The MCAS Yuma primary mission is to support aerial weapons training for the Atlantic and Pacific Fleet Marine Forces and Navy, and to serve as a base of operations for Marine Aviation Weapons and Tactics Squadron-1 and 3rd Marine Aircraft Wing units, including Marine Aircraft Group-13. The installation also provides non-airfield support operations and residential housing. Yuma International Airport shares runway privileges with MCAS Yuma, and their facility is located along the northernmost east–west runway.
Operations at the station began in 1928 when the United States (U.S.) Government leased 640 acres of land from the County of Yuma for use as an airfield. During World War II, the land was leased to the U.S. War Department, an air base was erected as part of the war effort, and the base became one of the busiest flying schools in the nation. Since that time, the facility has been used for a variety of U.S. Department of Defense missions.
On July 7, 1951, the Air Force reactivated the base, and the 4750th Air Base Squadron resumed training as part of the Western Air Defense Forces. The current MCAS was established when the facility was signed over to the DON in January 1959 to operate and maintain facilities and provide services to support operations of a USMC aircraft wing.
Non-airfield support operations include various administration buildings, barracks, health care facilities, a fuel farm, a water treatment plant, and other support facilities. The central portion of the North Airfield Operations Area is occupied by residential housing and athletic fields, and includes a child development center, a family childcare center, and a youth center. The southern portion of MCAS Yuma is mostly open space and includes an ordnance storage area, a closed landfill, a small agricultural operation, and stormwater catch basins.
Environmental Restoration Program Background
Environmental investigations and restoration activities have been ongoing at MCAS Yuma since the mid-1980s. Early studies conducted in the late 1980s found various contaminants in soil and chlorinated solvents in groundwater underlying the MCAS, which led to its inclusion on the USEPA National Priorities List, or Superfund list, on February 21, 1990. The Marine Corps entered into a federal facilities agreement (FFA) with the USEPA and ADEQ, signed on August 19, 1991, to establish a framework and schedule for implementing environmental investigations and appropriate cleanup actions. The contaminated areas at MCAS Yuma were divided into OUs 1 and 2 in accordance with the FFA.
OU 1 is comprised of areas with potential groundwater and soil contamination deeper than 10 feet below ground surface (bgs). A total of six areas were designated under OU 1, and two areas were transferred to the UST program. OU 2 is comprised of areas with potential soil contamination shallower than 10 feet bgs. A total of 20 CAOCs were designated under OU 2, with CAOC 8 divided into 8A and 8B, and CAOC 10 also divided into 10A and 10B. A third OU, OU 3, is designated for FFA Assessment Program sites that may be identified in the future.
As mandated by the National Defense Authorization Act of Fiscal Year 2002, the Department of Defense (DoD) developed the Military Munitions Response Program (MRP) to address military munitions under the DERP. This program was initiated specifically to address unexploded ordnance, discarded military munitions, and associated chemical residues referred to as munitions constituents on current and former military installations. Six MRP sites were identified at MCAS Yuma after the FFA, although the agreement was not formally amended to include these sites in an OU.
Records of Decision (RODs) for MCAS Yuma have been signed for OU 1, OU 2, and MRP Sites 4, 5 and 6, and a ROD for MRP Site 1A is in preparation.
CLICK HERE for information on the CERCLA process and the DON’s ERP.