The Fairchild Semiconductor Corp. Mountain View Plant is a 56-acre former semiconductor manufacturing facility in Mountain View, California. It has been on the National Priorities List (NPL) since 1991. The site is part of the Middlefield-Ellis-Whisman (MEW) Superfund Study Area, a cluster of contaminated facilities in the region. Investigations in 1981 and 1982 found widespread soil and groundwater contamination. A final remedy was selected in 1989, and construction was completed in 1999.
The main contaminants are chlorinated solvents, led by trichloroethene (TCE), along with tetrachloroethene, 1,1,1-trichloroethane, vinyl chloride, and various dichloroethene compounds. Heavy metals including arsenic, cadmium, lead, and antimony were also found in groundwater. Soil gas and groundwater are the affected media across the site's regional area.
Cleanup methods have included soil excavation, slurry walls to contain contamination, soil vapor extraction, and groundwater extraction and treatment systems. Soil cleanup is complete. Groundwater treatment has removed roughly 89,000 pounds of contaminants but must continue for many decades to meet the TCE cleanup standard of 5 parts per billion. In 2010, EPA added a vapor intrusion remedy using sub-slab depressurization, foundation sealing, and indoor air monitoring to reduce exposure to TCE and other volatile organic compounds in buildings. Because there is no current use of groundwater as a drinking water supply and no direct exposure pathways exist, the remedy is considered protective of human health in the short term.
The September 2024 Five-Year Review flagged two key concerns. First, the existing groundwater remedy is declining in efficiency, and EPA recommends evaluating faster cleanup technologies for shallow groundwater and soil gas. Second, per- and polyfluoroalkyl substances (PFAS) exceeding EPA limits were detected in groundwater, requiring further sampling and assessment. Groundwater migration has not yet been fully stabilized. Long-term protectiveness depends on addressing these issues. The site has not been deleted from the NPL. Despite ongoing cleanup, one business currently operates on-site, employing 1,000 people and generating about $1.68 billion in annual sales.
Community members can contact the Community Involvement Coordinator or the Remedial Project Manager. Site documentation includes 26 key documents, 46 progress reports, and 78 publicly available documents.
