Advanced Micro Devices once made semiconductor devices on a site in Sunnyvale, California. Underground storage tanks leaked volatile organic compounds (VOCs), chemicals used in metal processing and similar industries, into soil and groundwater starting around 1981. EPA added the site to the National Priorities List (NPL) in August 1990. The site has since been redeveloped for residential use, and cleanup work continues under ongoing federal oversight.
The main contaminants are VOCs in groundwater and soil. Trichloroethene (TCE) is the primary concern, along with tetrachloroethene, 1,1,1-trichloroethane, benzene, vinyl chloride, toluene, xylene, ethylbenzene, and chromium in groundwater. EPA identified 24 contaminants of concern in total. Contaminated soil was excavated and removed between 1982 and 1983. Groundwater is still being treated using air stripping and carbon adsorption through a pump-and-treat system.
Advanced Micro Devices carried out early removal work and installed extraction wells. The company later transferred the property to Spansion LLC in 2003. The current owner, Watt Investments at Sunnyvale LLC, redeveloped the site for residential use and installed vapor intrusion mitigation systems beneath new homes to block TCE vapors from entering living spaces. The State of California oversaw that redevelopment. The treatment system was upgraded and relocated in 2016, and groundwater extraction and treatment were still running as of 2024.
EPA's September 2024 Five-Year Review found the remedy currently protects human health and the environment. A land use covenant prevents groundwater from being used as drinking water and bars sensitive facilities like schools and daycares. The site does not affect municipal drinking water. However, the review flagged gaps: vapor intrusion has not been fully addressed, and the monitoring well network needs more downgradient wells to confirm the contaminant plume is contained. EPA recommended adding monitoring wells, sampling indoor air where elevated vapors were detected below building slabs, and conducting regular system inspections. Contaminants migrating from upgradient sources continue to challenge long-term cleanup goals. One source states human exposure is under control and contamination is stabilized, while the 2024 Five-Year Review notes vapor intrusion has not been fully addressed, so both claims are reflected here as stated in the source materials.
Community members with questions about site cleanup can contact the EPA Remedial Project Manager. The site remains on the NPL and under operation and maintenance, with the next five-year review expected in the future.
