Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Fairchild Semiconductor Corp. (Mountain View Plant)
EPA #: CAD095989778
County: Santa Clara
City: Mountain View
Congressional District: 14
Other Names: Part of Middlefield-Ellis-Whisman (MEW) Study Area
EPA’s Final Third Five-Year Review report for the MEW Site is available to view [Click here].
On this page
Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 10/15/84
Final Date: 02/11/91
The 56-acre former Fairchild Semiconductor Corp. - Mountain View facilities manufactured semiconductors and is located in Mountain View, California. The Fairchild Semiconductor Corp - Mountain View site is one of three Superfund or National Priorities List (NPL) sites that are being cleaned up simultaneously. The other two Superfund sites are the Intel - Mountain View site and the Raytheon site. All three sites are located in the Middlefield-Ellis-Whisman (MEW) Study Area and are being addressed collectively as the MEW SIte. Site investigations at several of these facilities during 1981 and 1982 revealed extensive soil and groundwater contamination, primarily volatile organic compounds (VOCs).
Fourteen potential sources of contamination have been identified at the former Fairchild facilities, including underground and aboveground storage tanks for chemical products and wastes, pH neutralization systems, and industrial wastewater treatment systems.
Contaminants and Risks
- Soil and Sludges
The primary contaminant of concern is trichloroethene (TCE). The soil has been cleaned up to meet the soil cleanup standards
Who is Involved
This site is being addressed through Federal and potentially responsible parties' actions.
Investigation and Cleanup Activities
The contamination addressed in the MEW Record of Decision is both facility-specific and regional. Each individual MEW Company is responsible for investigation, cleanup, and source control for soil and groundwater contamination at their individual facility-specific properties south of U.S. Highway 101. Contaminated groundwater that has bypassed the source control areas and has mixed together with other contaminated groundwater from other source areas is considered part of the regional groundwater contamination plume, or the “regional plume.”
The MEW Regional Groundwater Remediation Program systems south and north of U.S. Highway 101 are designed to contain and clean up contaminated groundwater where it has mixed together with other contaminated groundwater and where the source of contamination has not been identified. The Navy and NASA both operate groundwater extraction and treatment systems to contain and clean up contaminated groundwater at their areas of responsibility on Moffett Field, in addition to the regional system operating North of 101 on Moffett Field.
It is important to note that groundwater currently is not used for drinking water or other potable uses. Groundwater in the area is, however, a potential future source of drinking water and therefore groundwater cleanup standards have been established.
Initial cleanup actions included removing tanks from the site, removing and treating soil, sealing wells serving as potential conduits, and controlling groundwater movement by installing three slurry walls and 21 groundwater extraction wells.
In June 1989, EPA issued a Record of Decision selecting the soil and groundwater cleanup remedy for the MEW Site. The soil remedy includes: excavation, with treatment by aeration; and soil vapor extraction with treatment by vapor-phase granular activated carbon. The groundwater remedy includes: slurry walls (barriers beneath the surface) to contain contaminants; and extraction and treatment systems to contain and clean up groundwater contamination using granular activated carbon and/or air-stripping systems.
Because the groundwater contamination at the MEW Site migrates northward and has mixed with contamination from sources at the NAS Moffett Field Superfund site, the groundwater remedy selected in the MEW Record of Decision also applies to the commingled regional groundwater contamination area on former NAS Moffett Field (the West-Side Aquifers), but not the entire former NAS Moffett Field facility.
515/545 Whisman Road and 313 Fairchild Drive (Former Buildings 1-4)
In 1986, Fairchild installed a 40-foot deep slurry wall along the property boundaries to limit migration of chemicals, and was keyed into the A/B aquitard. Groundwater extraction was initiated in the mid-1980s to control and clean up sources in the groundwater. The system was expanded and currently includes 12 source control extraction wells both inside and outside the slurry wall. The MEW Regional Program operates three wells outside the slurry wall. Treatment systems 1 and 3 have treated over an estimated 900 million gallons of groundwater and removed over 34,000 pounds of VOCs from the groundwater through December 2006.
401 National Avenue (Former Building 9)
In 1986, Fairchild installed a slurry wall along the boundaries of this property and that was keyed into the A/B aquitard at a depth of approximately 40 feet. Groundwater extraction began at this property in 1982 from well 65A. Since then, the groundwater system has been expanded to include four source control extraction wells within the slurry wall enclosure. Extracted groundwater from the five A Aquifer wells is treated at System 1. Three other source control extraction wells (GSF-1A, GSF-1B1, and GSF-1B2) have also been installed north of this facility and are the joint responsibility of Vishay/SUMCO and Fairchild/Schlumberger.
369 and 441 North Whisman Road (Former Buildings 13, 19, 23)
In 1986, Fairchild installed an approximately 40-foot-deep slurry wall along the boundaries of the 369 North Whisman Road property, keyed into the A/B aquitard. Groundwater extraction began in 1982 at this property, and was expanded to include seven A Aquifer source control extraction wells within the slurry wall enclosure; two A Aquifer source control extraction wells downgradient of the slurry wall to the north; three source control extraction wells in the B1 Aquifer; and two source control extraction wells in the B2 Aquifer. Groundwater extracted from these wells is piped to System 19, located at 369 North Whisman Road, for treatment. System 19 has treated over 800,000 gallons of groundwater and removed over 10,000 pounds of VOCs from the groundwater through December 2006.
644 National Avenue (Former Building 18)
One source control extraction well (RW-25A) currently operates in the A Aquifer northwest of the building. Groundwater from this extraction well is treated at System 1.
464 Ellis Street (Former Building 20)
No potential sources were found at this property. Raytheon installed and currently operates two source control extraction wells in the A and B1 Aquifers, respectively. These wells capture contaminants immediately downgradient of the Raytheon slurry wall. Groundwater from the two wells is conveyed to the Raytheon system at 350 Ellis Street for treatment.
The MEW Companies, Navy and NASA are preparing work plans to optimize the groundwater cleanup at the MEW Site.
EPA Evaluates Vapor Intrusion Pathway
The 1989 soil and groundwater remedy at the MEW Site did not address risks from long-term exposure through the vapor intrusion pathway. Since the issuance of EPA’s 1989 Record of Decision, new information was developed regarding the toxicity of TCE and potential vapor intrusion into buildings overlying shallow groundwater contamination. In 2003, as part of EPA’s Five-Year Review of the MEW Study Area, EPA began evaluating whether VOCs in shallow groundwater are potentially migrating upward through the soils and cracks in the floors or through plumbing conduits and other preferential pathways, and impacting indoor air.
Based on indoor air sampling of both commercial and residential buildings in the area conducted in 2003 to 2008, EPA confirmed the presence of the subsurface vapor intrusion pathway into a number of structures overlying the shallow groundwater TCE plume. EPA’s main concern is whether the chemicals from the Site measured in indoor air pose an unacceptable risk of chronic health effects due to long-term exposure (25 years or more). It is EPA’s policy not to set cleanup levels or take action to reduce levels that are less than ambient background levels.
Some of the sampled buildings indicated indoor air contaminant concentrations that were elevated above background levels and above EPA Region 9’s TCE interim action level in indoor air for long-term exposure. In each of these buildings, the MEW Companies, Navy, and NASA implemented interim measures (e.g., sealing cracks/conduits, upgrading/modifying ventilation systems, installing air purifying systems) to reduce the indoor air contaminant concentrations.
In 2010, EPA amended the MEW Record of Decision and selected a remedy that addressed potential long-term exposure of TCE, and other VOCs at unacceptable levels, through the vapor intrusion pathway, For more information, please access the 2010 Record of Decision Amendment for the Vapor Intrusion Pathway document either by clicking here or finding it in the Records of Decision subsection of the Documents and Reports section below.
In 1985, EPA issued an Administrative Order on Consent to the parties potentially responsible for site contamination. As a result of this Order, the potentially responsible parties conducted an investigation to determine the nature and extent of the site contamination. In 1990, EPA issued an Administrative Order requiring the clean up of the sites and responsibility for the long-term operation of the regional groundwater extraction system.
Cleanup Results to Date
Under EPA’s direction and oversight, the MEW Companies, including Fairchild Semiconductor Corp. and Schlumberger Technology Corp., implemented the soil and groundwater cleanup programs that have included soil excavation and treatment, installation of four slurry walls, soil vapor extraction and treatment systems, and groundwater extraction and treatment systems. The soil cleanup by soil vapor extraction and excavation and aeration has been completed at all the former MEW facilities, including the former Fairchild facilities.
Groundwater cleanup will continue to operate for many decades in order to meet the TCE groundwater cleanup standard of 5 parts per billion. The MEW Site groundwater remedy has removed over 100,000 pounds of contaminants, and has reduced contaminant concentrations throughout the multiple aquifer zones. The groundwater is not being used as a potable water supply, and there are no direct exposure pathways to the contaminated groundwater while groundwater cleanup continues.
The Third Five-Year Review Report, completed on September 29, 2014, concluded that -
- The groundwater remedy at the MEW Site is currently protective of human health and the environment because exposure to groundwater is being controlled. In order to be protective in the long term, the following recommendations and follow-up actions need to be completed:
• Determine the source of the TCE hot spot areas on Evandale Avenue and extent of TCE contamination in the A and B1 aquifer zones;
• Evaluate alternative cleanup strategies inside the slurry walls and implement treatability studies that do not necessarily require maintaining inward and upward gradients to control source area contamination;• Evaluate and implement the current optimization pilot tests and treatability studies of alternative groundwater cleanup technologies at the facility-specific source areas, TCE hot spot areas, and representative areas of the regional groundwater contamination plume to expedite contaminant mass removal and cleanup timeframe; and
• Based on evaluation of the information collected, complete a Feasibility Study to evaluate remedial alternatives that can effectively meet the vapor intrusion remedial action objective to accelerate the reduction of the source of vapor intrusion (i.e., Site contaminants in shallow groundwater and soil gas) to levels that are protective of current and future building occupants, such that the need for a vapor intrusion remedy would be minimized or no longer be necessary.
Potentially Responsible Parties
Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.
Under EPA's direction and regulatory oversight, Schlumberger Technology Corporation is responsible for investigating and cleaning up the soil and groundwater at the Fairchild-Mountain View Superfund Site. In addition, the following individual companies are responsible for investigating and cleaning up the groundwater at the MEW Site. These companies are collectively referred to as the MEW Companies:
- Fairchild Semiconductor Corporation
- Intel Corporation
- Raytheon Company
- Schlumberger Technology Corp. (Schlumberger)
- Renesas Electronics America Inc. (formerly NEC Electronics America, Inc.)
- SMI Holding LLC (SMI)
- Vishay General Semiconductor (Vishay)
- SUMCO Phoenix Corporation (SUMCO)
- National Semiconductor Corporation
- Tracor X-Ray
- Union Carbide
National Semiconductor Corporation, Tracor X-Ray, and Union Carbide are not involved with the active investigation and cleanup of the MEW Site.
Documents and Reports
Public Meetings: A community advisory group, the MEW Community Advisory Board, meets to learn about and discuss MEW Superfund Study Area investigation and cleanup issues.
EPA has awarded a Technical Assistance Grant (TAG) to the Pacific Studies Center. The TAG provides money for activities that help the community understand technical information at the MEW Site. Please contact Lenny Siegel, TAG Administrator, at 650-961-8918 or LSiegel@cpeo.org for more information.
Public Information Repositories
The public information repositories for the site are at the following locations:
Mountain View Public Library,
585 Franklin Street,
Mountain View, CA 94041
Monday-Thursday 10 am to 9 pm
Friday and Saturday 10 am to 6 pm
Sunday 1 pm to 5 pm
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
a Project of the Pacific Studies Center,
278A Hope Street
Mountain View, CA 94041
After Hours (Emergency Response)