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

This site is located in the Basin and Range lowlands province that covers most of southern Arizona. This physiographic province is characterized by elongated northwest-southeast trending fault-block mountain ranges separated by broad, deep alluvial valleys.

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.

Groundwater in the upper fine-grained unit is generally characterized as slightly saline with total dissolved solids (TDS) of 1,000 to 3,000 milligrams per liter (mg/l). The primary regional aquifer is the coarse gravel unit that underlies the upper fine-grained unit. Groundwater in this unit is generally characterized as slightly saline with TDS of 1,000 to 3,000 mg/l.

The direction of groundwater flow beneath the site is from southeast to northwest. Water levels have declined 6 to 8-feet (ft.) since the late 1990’s