Moffett Naval Air Station sits on a 1,500-acre facility in Moffett Field, Santa Clara County, California. Military operations dating back to 1933 left behind widespread contamination in groundwater, soil, sediment, and air. The site was first assessed in December 1984 and added to the EPA's National Priorities List in July 1987. NASA took ownership of the airfield when it closed in 1994 and the property transferred to NASA Ames Research Center.
More than 100 chemical substances have been identified as contaminants of concern. Soil holds metals such as lead, cadmium, arsenic, beryllium, and nickel, along with organic compounds including trichloroethene, tetrachloroethene, and benzene. Groundwater contains volatile organic compounds like trichloroethene, tetrachloroethene, vinyl chloride, chloroform, and 1,1,1-trichloroethane. Sediment in channels and marshes carries cadmium, lead, mercury, selenium, DDT compounds, PCBs, and chlordane. Soil gas also contains trichloroethene, tetrachloroethene, and vinyl chloride. Over 30 hazardous waste sites have been identified across the facility.
The EPA leads regulatory oversight. The Navy and NASA carry out investigation and cleanup work, with support from the state Regional Water Quality Control Board. Cleanup actions have included landfill capping, soil and sediment excavation, groundwater extraction and treatment, wetland restoration, and removal of contaminated building materials. Six sites required no further action after EPA found they posed no threat. A groundwater treatment system in the East-Side Aquifer area shifted to enhanced treatment and monitored natural attenuation in 2014, with treatment injections beginning in 2019. The most recent five-year review, completed in September 2024, found that response actions remain protective of human health and the environment in the short term.
Human exposure across the site is currently under control, meaning no unacceptable pathways exist for people to contact contaminants at unsafe levels. However, groundwater migration is not under control. Contaminated groundwater is still moving beyond its original area. Physical construction is not yet complete at all operable units. Active removal work at Site 25 is estimated to finish between June and August 2026, and a removal project at NASA AOI 14 is estimated to wrap up between January and March 2027. The site has not yet been deleted from the National Priorities List.
Community members can attend public meetings held anually by the Navy's Restoration Advisory Board, typically on the third Thursday of October from 7:00 to 9:00 p.m. at the Mountain View Center, Redwood Room, 201 S. Rengstorff Avenue, Mountain View, California. People can also join the Community Advisory Group (CAG) by contacting the CAG contact listed for this site. For questions about cleanup, contact the EPA's Remedial Project Manager.
