JASCO Chemical Corporation operated in Mountain View, California from 1976 to 1995. Waste disposal practices and leaks from underground storage tanks contaminated soil and groundwater with chlorinated solvents, volatile organic compounds, and petroleum products. EPA identified 27 contaminants of concern, including trichloroethene, tetrachloroethene, benzene, toluene, xylene, and total petroleum hydrocarbons. Vapors from contaminated soil also required treatment. The site was added to the National Priorities List in October 1989 and organized under one operable unit covering the overall site.
EPA selected a cleanup remedy in September 1992 that included excavating contaminated soil, extracting and treating groundwater, using soil vapor extraction, and applying bioremediation along with institutional controls. Construction of cleanup systems ran from July 1996 through September 2002, when the groundwater treatment system was shut down after meeting cleanup goals. Sampling confirmed all cleanup standards for soil and groundwater had been achieved. Five-year reviews completed in 2007 and 2012 confirmed the remedy continued to protect human health and the environment. The site was deleted from the Superfund National Priorities List on September 30, 2020.
Human exposure is currently under control and groundwater migration is stabilized with no unacceptable discharge to surface water. Perchloroethylene (PCE) remains in groundwater, but EPA determined it comes from an unknown off-site source, not from JASCO operations. A health risk assessment found the PCE poses no risk for future redevelopment. EPA referred PCE oversight to California's Regional Water Quality Control Board. An environmental deed restriction on the property requires any redevelopment activity to follow a Soil Management Plan, and construction work must be reviewed and approved by the Regional Water Quality Control Board and EPA.
A private developer is building a 226-unit apartment building on the former site, and the City of Mountain View plans additional future redevelopment. Zoning restrictions and other institutional controls remain in place to ensure land uses stay consistent with the level of cleanup achieved.
Community members can get more details about the site through EPA's published fact sheet on the delisting, available in the EPA publications database. The Federal Register docket number for the deletion is EPA-HQ-SFUND-1989-0011-0141. Questions can be directed to the EPA Community Involvement Coordinator or the Remedial Project Manager.
