Spectra-Physics, Inc. is an 11.5-acre former electronics and gas laser manufacturing site in Mountain View, California. Operations there since 1961 released chlorinated solvents into soil and groundwater. The site was added to the federal Superfund National Priorities List on February 11, 1991, and cleanup work has been ongoing for over 30 years. About 189,000 people live within 3 miles of the site, with the nearest residence just 200 feet away.
The main contaminants are volatile organic compounds (VOCs), a group of chemicals that evaporate easily and can move through soil and air. The most widespread is trichloroethylene (TCE), found in soil, groundwater, and indoor air. Other contaminants include tetrachloroethylene, vinyl chloride, 1,1-dichloroethane, chloroform, and toluene, among 17 total chemicals identified. Contaminated groundwater from a neighboring site, Teledyne Semiconductor, merged with the plume here, so the two companies are cleaning up together. City drinking water comes from the Hetch Hetchy Reservoir and is not affected by site contamination.
Cleanup is organized into two operable units. The first covers the overall site. Early work included soil vapor extraction and groundwater treatment. In September 2020, EPA added vapor intrusion mitigation measures such as sub-slab depressurization and foundation sealing. In September 2023, EPA switched the groundwater cleanup method from extraction to bioremediation, injecting a substrate to help naturally occurring microorganisms break down contaminants. This change is expected to speed up cleanup significantly. The second operable unit focuses specifically on vapor intrusion, which occurs when contaminated groundwater vapors seep into buildings through foundation cracks. A Record of Decision for vapor intrusion was issued in September 2020, and remedial work under that decision is ongoing.
The most recent five-year review, completed September 25, 2024, found that soil and groundwater remedies are short-term protective. Vapor intrusion remedies will be protective once fully implemented. The review flagged gaps, including the need for more residential indoor air sampling, a long-term monitoring plan, assessment of a sewer-to-indoor-air vapor pathway, and evaluation of PFAS contamination in groundwater. EPA has determined that human exposure is under control and groundwater migration is stabilized. The site was declared ready for anticipated reuse in June 2021 and currently supports 7 businesses employing 156 people.
Community members who want to review site documents can visit the EPA Superfund Records Center at 75 Hawthorne Street in San Francisco, open Monday through Friday from 8 a.m. to 5 p.m., or the San Francisco Bay Water Quality Control Board at 1515 Clay Street in Oakland.
