The Westinghouse Electric Corporation Sunnyvale Plant is a 75-acre former electrical transformer manufacturing facility in Sunnyvale, California. It was added to the EPA's National Priorities List in June 1986. Today, the site is actively used by businesses, including Northrop Grumman, which purchased the property in 1996 and employs hundreds of workers there.
Seventeen contaminants of concern have been identified in soil and groundwater at the site. Groundwater contains chlorinated solvents such as trichloroethene, 1,1,1-trichloroethane, and 1,1-dichloroethene, along with benzene, toluene, ethylbenzene, xylene, and various dichlorobenzenes. Polychlorinated biphenyls, or PCBs, were found in both soil and groundwater, the result of a leaking storage tank and localized spills during the facility's operating years.
Cleanup began with soil removal in 1984 and 1985, followed by removal of a gasoline tank in 1986. A formal Remedial Investigation started in October 1981, and the final remedy was selected in October 1991. That remedy includes groundwater extraction wells, air stripping, ultraviolet oxidation, carbon adsorption, excavation, offsite incineration of contaminated soil, engineered caps, and institutional controls. Full-scale groundwater treatment started in early 1995. Remedial action construction wrapped up in September 2000. An asphalt cap limits soil PCB exposure, and land use covenants restrict how the property can be used. The groundwater extraction system provides hydraulic containment of the contaminated source area, preventing pollutants from spreading into shallow aquifers.
The site achieved ready-for-anticipated-use status in May 2019, meaning cleanup goals for current and expected future uses have been met and land-use controls are in place. Human exposure is currently under control, with no unacceptable exposure pathways identified. Groundwater migration is also under control, with no unacceptable discharge to surface water expected. However, EPA has determined that remedy adjustments or an optimization study should be done to restore groundwater outside the source areas to beneficial use within a reasonable timeframe. About 710,000 people live within three miles of the site, and roughly 300,000 depend on groundwater in that area for drinking water. Municipal wells sit within a quarter-mile of the site.
EPA is conducting its Sixth Five-Year Review in 2026, with the report due by September 30, 2026. The review will include a site inspection, a look at cleanup technology performance, a review of site data and maintenance records, and an evaluation of any new laws that could affect the cleanup. Community members can get information by contacting the EPA's Community Involvement Coordinator or Remedial Project Manager. A copy of the completed review will also be available at EPA's Superfund Records Center at 75 Hawthorne Street, 3rd Floor, San Francisco, CA 94105, or by calling 415-947-8717.
