Applied Materials operated a semiconductor fabrication equipment facility on a 9-acre property in Santa Clara, California starting in 1974. Leaking pipes connected to underground storage tanks contaminated groundwater with volatile organic compounds (VOCs), a class of chemicals widely used in electronics manufacturing. EPA added the site to the National Priorities List (NPL) in 1987, which identifies sites that need further federal cleanup attention.
Thirteen contaminants have been identified in groundwater at the site. These include trichloroethene, tetrachloroethene, vinyl chloride, chloroform, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1-dichloroethane, 1,1-dichloroethene, 1,2-dichloroethane, cis-1,2-dichloroethene, trans-1,2-dichloroethene, and trichlorofluoromethane. Soil contamination was initially suspected but studies confirmed soils are not affected. Area drinking water wells have not been impacted by the contaminant plume.
Applied Materials installed a groundwater pump-and-treat system in 1984, using three extraction wells and an air stripper to pull contaminants out of the water. Active groundwater extraction ran from 1985 through December 2002, when it was shut down after contaminant levels had dropped significantly. Underground storage tanks were removed in 1985. The remedial investigation began in October 1983, and a remedy was formally selected in September 1990. Cleanup construction was completed by September 1993. A separate operable unit covering a specific area of the site received a determination in August 1993 that no further action was needed there. An institutional control now restricts groundwater from being used as a drinking water source.
Since 2002, the site has been under chemical attenuation monitoring, which tracks whether natural processes continue to reduce contaminant levels over time. Current monitoring data show concentrations are still decreasing. EPA has recommended continuing annual monitoring at the four remaining wells. The site was declared ready for anticipated reuse in September 2010, and in 2003 the company converted its former industrial building to office and educational use. One business currently operates on site. EPA's most recent five-year review, completed September 30, 2025, found that cleanup actions remain protective of public health and the environment. The site has not yet been deleted from the NPL.
Community members with questions can contact the EPA's Community Involvement Coordinator. Technical questions can go to the Remedial Project Manager. Public records related to the site are available at the EPA Regional Records Center at 75 Hawthorne Street, Room 3110, in San Francisco, California.
