Superfund Site | Marine Corps Air Station Yuma

Environmental Protection Agency (EPA)#: AZ0971590062

Date Placed on National Priority List (NPL): Feb. 21, 1990


Marine Corps Air Station (MCAS) Yuma occupies approximately 4,800 acres within the city and county of Yuma, Arizona. The site is bounded by South Avenue 3E on the east, 32nd Street on the north, East County 14th Street on the south, and the city of Yuma Main Canal on the west. Plume boundaries vary and may extend beyond the site boundary while remaining part of the Superfund site in its entirety.

Contaminants of concern

The contaminated media includes groundwater and soil. For groundwater, contaminants of concern (COCs) include chlorinated solvents (trichloroethene (TCE), dichloroethene (DCE), tetrachloroethene (PCE)) and volatile organic compounds (petroleum hydrocarbons). For soil, COCs include total residual petroleum hydrocarbons (TRPH), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, metals, and munitions and explosives of concern (MEC). As new information becomes available, COCs may change.

Site Hydrogeology

Hydrogeologic units defined for the site are: upper fine-grained unit, coarse gravel unit and wedge unit. Many shallow wells on the Yuma Mesa are screened in the upper fine-grained unit, and water quality is variable due to the large volume of irrigation recharge. The primary regional aquifer is the coarse gravel unit that underlies the upper fine-grained unit.

The direction of groundwater flow beneath the site is from southeast to northwest. Water levels have declined 6 to 8 feet starting in the late 1990s, but began slowly increasing again beginning in 2017 and have increased approximately 3 to 5 feet since then.

Action taken

During its 70 years of operation, MCAS Yuma generated industrial wastes such as used oil, solvents, paint residues, battery acid, pesticides, herbicides, polychlorinated biphenyls, asbestos in the form of non-friable asbestos containing material (ACM), and petroleum hydrocarbons from a jet fuel leak. The ACM was scattered on top of and buried in the surface soil. It was remediated in 1999.

Established in 1991, the federal facilities agreement and assessment program identified three operable units (OUs): OU-1 contains contaminated groundwater and soil deeper than 10 feet below ground surface (bgs). OU-2, which is comprised of 18 Comprehensive Environmental Response Compensation and Liability Act (CERCLA) Area of Concern (CAOC) sites, contains contaminated soil from ground surface to 10 feet bgs. OU3 did not identify any specific CERCLA sites and is thus intended to be used for future sites if required.