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NPL Site Narrative for National Semiconductor Corp.
NATIONAL SEMICONDUCTOR CORP.
Santa Clara, California
Federal Register Notice: July 22, 1987Conditions at proposal (October 15, 1984): National Semiconductor Corp. manufactures electronic equipment at a plant in Santa Clara, Santa Clara County, California. The facility occupies about 50 acres and is surrounded by residential, industrial, and business areas.
Monitoring wells on the site are contaminated with vinyl chloride, trichloroethylene, and 1,1-dichloroethylene, according to analyses conducted by a consultant to National Semiconductor Corp. Contamination is believed to have resulted from leaking underground storage tanks. The same contaminants have been detected in monitoring wells off the facility. About 300,000 people depend on wells within 3 miles of the site as a source of drinking water.
National Semiconductor has taken the leaking tanks out of service and is working with the California Regional Water Quality Control Board (CRWQCB) to determine the extent of ground water contamination.
This is one of 19 sites in the South Bay Area of San Francisco. Facilities at these sites have used a variety of toxic chemicals, primarily chlorinated organic solvents, which contaminate a common ground water basin. Although these sites are listed separately, EPA intends to apply an area-wide approach to the problem as well as take specific action as necessary.
Status (February 1986): Under the direction of CRWQCB, the company has commenced a program of pumping and treating ground water to contain the plume while the remedial investigation is underway. CRWQCB, in conjunction with EPA and the California Department of Health Services, is overseeing the various response actions.
EPA believes that it may be possible to clean up this site under Subtitle C of the Resource Conservation and Recovery Act (RCRA). This site remains in proposed status until EPA implements the appropriate elements of its final policy for placing RCRA-related sites on the NPL and then applies the policy to this site.
Status (July 22, 1987): Subsequent investigation revealed that this site is not subject to the Subtitle C permitting requirements of RCRA. Its score on the Hazard Ranking System, which EPA uses to evaluate sites for the NPL, is above the cutoff point of 28.50, and EPA received no information that prevents placing the site on the NPL. Therefore, it is being placed on the NPL.
For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737.