Jump to main content or area navigation.

Contact Us

Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

Middlefield-Ellis-Whisman (MEW) Study Area

EPA #: CAD982463812

State: California(CA)

County: Santa Clara

City: Mountain View

Congressional District: 12

Other Names: Please also see Site Overviews for Raytheon, Intel Corp - Mtn View, and Fairchild Semiconductor - Mtn View

Bulletin Board

Links

Description and History

NPL Listing History

NPL Status: Part of another site

Proposed Date:

Final Date:

Deleted Date:

The Middlefield-Ellis-Whisman (MEW) Superfund Study Area (or MEW Site) is comprised of three National Priorities List (NPL) or Superfund sites: Fairchild Semiconductor Corp. – Mountain View Superfund site; Raytheon Company Superfund site; and Intel Corp. – Mountain View Superfund site; several other facilities; and portions of the former Naval Air Station (NAS) Moffett Field Superfund site. The "MEW Superfund Study Area" itself is not listed on the National Priorities List (NPL).

    The MEW Site was home to several manufacturing and industrial facilities, including semiconductor and other electronics manufacturing facilities and metal finishing facilities. While in operation, these former facilities required the storage, handling, and use of a variety of chemicals, particularly volatile organic compounds (VOCs). The primary chemicals of concern at the MEW Site are trichloroethene (TCE) and its degradation products: cis-1,2-dichloroethene and vinyl chloride. During operations, some of the chemicals leaked or were otherwise released to the ground, impacting soil and groundwater. In 1981 and 1982, investigations in the area of these facilities indicated that significant levels of contaminants had been released to the soil and groundwater.

Top of page

Contaminants and Risks

Contaminated Media
  • Groundwater
  • Air

The primary contaminants of concern are trichloroethene (TCE) and other volatile organic compounds (VOCs) in groundwater and the potential migration to indoor air (vapor intrusion pathway). The soil has been cleaned up to meet the soil cleanup standards.

Top of page

Who is Involved

The MEW Site is being addressed through EPA and potentially responsible parties' actions.

Top of page

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 (South and North of 101) are designed to contain and clean up contaminated groundwater where the contaminated plume 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 MEW regional groundwater 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.

Remedy Selected

EPA's Soil and Groundwater Remedy - 1989 In June 1989, EPA issued a Record of Decision selecting the soil and groundwater cleanup remedy for the MEW Study Area. 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.

Intel, Fairchild, and Raytheon implemented groundwater and soil source control measures in the 1980s, before the soil and groundwater remedy was selected. Based on extensive soil and groundwater investigations and studies at the MEW Site, the MEW Companies implemented soil and groundwater cleanup programs that included soil excavation and treatment, installation of four slurry walls, soil vapor extraction and treatment systems, and groundwater extraction and treatment systems.

In the mid-1990s, Fairchild Semiconductor, Raytheon, Intel, and other MEW Companies (SMI, Vishay/SUMCO, NEC Electronics) implemented the soil remedy by excavation and aeration and soil vapor extraction (SVE). They also began operating or continued to operate the groundwater extraction and treatment systems to control source areas and remove VOCs from the aquifers. The soil cleanup was completed in 2001.

In accordance with the Consent Decree and 106 Order, each of the MEW Companies operates and maintains individual facility-specific groundwater source control measures (i.e., extraction wells, slurry walls, treatment systems, etc.) to contain and clean up contamination source areas in each area for which the MEW Company is responsible.

The MEW Regional Program South of 101 began operation in January 1998; North of 101 began operation in October 1998. The South of 101 and North of 101 are two separate groundwater extraction systems; however, they are designed to operate in unison to remediate and capture the regional plume. The Navy’s West-Side Aquifers Treatment System (WATS) began operation in November 1998, and NASA’s groundwater extraction and treatment system began operation in September 2001.

EPA's First Five-Year Review (2004)

The existing soil and groundwater remedy at the MEW Site does not address risks from long-term exposure through the vapor intrusion pathway. Since the issuance of EPA’s 1989 Record of Decision, new information has been developed regarding the toxicity of TCE and potential vapor intrusion into buildings overlying shallow groundwater contamination. In 2003, as part of EPA’s First Five-Year Review of the MEW Superfund 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.

EPA's First Five-Year Review determined that for the groundwater remedy to remain protective in the long-term, the following actions need to be taken: long-term protectiveness should continue to be verified by monitoring the extent of groundwater contamination along the estimated groundwater contamination plume boundaries. This evaluation should be accomplished through routine annual groundwater sampling events. Current data indicate that the remedy is functioning as required to meet the remedial action objectives; however, EPA recommends optimization of both the regional and facility-specific systems to enhance plume capture, evaluation of applicable technologies to potentially expedite contaminant mass removal and cleanup time, and evaluation of the potential need for institutional controls.

Current actions

Intel has mplemented an in-situ bioremediation pilot test at its former facility at 365 East Middlefield Road in Mountain View to try to reduce VOC concentrations in the “hot spot” areas in a shorter period of time.

The MEW Companies, Navy and NASA have prepared a work plan to evaluate other alternate groundwater cleanup technologies to address the MEW Site-wide groundwater contamination.

EPA continues to implement the following actions:

  • Ongoing evaluation of buildings overlying the shallow TCE plume to identify potential vapor intrusion pathways into buildings;
  • Implement vapor intrusion mitigation measures to reduce elevated levels of TCE in indoor air, as appropriate;
  • Assess various alternatives and propose a remedy to address the vapor intrusion pathway.

Top of page

Cleanup Results to Date

Under EPA’s direction and oversight, the MEW Companies 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.
Groundwater cleanup will continue to operate for many decades in order to meet the TCE groundwater cleanup standard of 5 parts per billion. The 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.

Top of page

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, the following individual companies are responsible for investigating and cleaning up the soil and 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.

    In accordance with a Consent Decree and Unilateral Administrative Order, each of the MEW Companies operates and maintains individual facility-specific groundwater source control measures (i.e., groundwater extraction wells and treatment systems, slurry walls, etc.) to contain and clean up contamination source areas in each area for which the MEW Company is responsible. Additionally, both the Navy and NASA operate individual groundwater extraction and treatment systems. Ongoing groundwater cleanup activities at the MEW Site are performed according to specifications in the individual facility-specific and Regional Program design, construction, operations and maintenance, and monitoring documents.

Top of page

Documents and Reports

Show details for Administrative RecordsAdministrative Records
Show details for Community InvolvementCommunity Involvement
Show details for Fact SheetsFact Sheets
Show details for Legal DocumentsLegal Documents
Show details for MapsMaps
Show details for Records of DecisionRecords of Decision
Hide details for Technical DocumentsTechnical Documents
09/30/04Final First Five Year Review Report
03/01/05Final Environmental Issues Management Plan for NASA Research Park
04/08/092008 Annual Progress Report for 455, 485/487 and 501/505 East Middlefield Road
04/15/092008 Annual Progress Report for 401/405 National Avenue site
04/15/092008 Annual Progress Report for 501 Ellis Street
04/15/092008 Annual Progress Report for Intel
04/15/092008 Annual Progress Report for Raytheon
06/15/092008 Annual Progress Report for Fairchild
06/15/092008 Annual Progress Report for MEW Regional Study Area
06/15/092008 Annual Progress Report for WATS and EATS
06/29/09Final Supplemental Feasibility Study for the Vapor Intrusion Pathway
06/29/09Final Supplemental Remedial Investigation for the Vapor Intrusion Pathway
07/09/09Proposed Plan for the Vapor Intrusion Pathway (updated to fix Table 3 title to Future Buildings)
08/20/09EPA Potential Changes to Proposed Vapor Intrusion remedy - Aug 20, 2009
08/20/09Updated to reflect extended public comment period - Proposed Plan for the Vapor Intrusion Pathway
09/18/09Cover page of Proposed Plan updated to reflect public comment period extended to Nov 7, 2009 - Proposed Plan for Vapor Intrusion Pathway
09/30/09Final Second Five-Year Review for the MEW Superfund Study Area
11/07/09Public Comments Received on EPA's Proposed Plan for the Vapor Intrusion Pathway during public comment period (July 10 - Nov 7, 2009)
04/15/102009 Annual Progress Report for Former Intel- Mtn View facility - 365 E. Middlefield Road
04/15/102009 Annual Progress Report for former NEC 501 Ellis Street
04/15/102009 Annual Progress Report for Former Raytheon Facilities - 350 Ellis Street
04/15/102009 Annual Progress Report for SMI 455, 485/487 and 501/505 East Middlefield Road
04/15/102009 Annual Progress Report for Vishay/SUMCO/Fairchild 405/425 National Ave
05/01/102009 Regional Groundwater Remediation Program Progress Report - Restoration Program, NASA Ames Research Center
06/15/10 2009 Annual Progress Report for MEW Regional Groundwater Remediation Program
06/15/102009 Annual Progress Report for former Fairchild facilities - Bldgs 1-4, 9, 18, 19, 20
06/15/102009 Annual Progress Report for MEW Regional Groundwater Remediation Program
06/30/102009 Annual Progress Report for WATS and EATS Areas (excluding Appendix C)
04/11/112010 Annual Progress Report for SMI 455, 485/487 and 501/505 East Middlefield Road
04/15/112010 Annual Progress Report for former NEC/Renasas 501 Ellis Street
04/15/112010 Annual Progress Report for Former Raytheon - 350 Ellis Street
04/15/112010 Annual Progress Report for Vishay/SUMCO/Schlumberger 405/425 National Avenue
04/15/112010 Annual Status of Enhanced In-situ Bioremediation Pilot Test for Former Intel/Raytheon 365/401 East Middlefield Road
05/01/112010 Regional Groundwater Remediation Program Progress Report - Restoration Program, NASA Ames Research Center
06/15/112010 Annual Groundwater Report for Moffett Field Site 26 EATS Area and Site 28 WATS Area [excluding Appendix C]
06/15/112010 Annual Progress Report for former Fairchild facilities - Bldgs 1-4, 9, 18, 19, 20
06/15/112010 Annual Progress Report for MEW Regional Groundwater Remediation Program
09/12/11Building-Specific Air Sampling Report for Buildings 23, 48, 146, 503, 543, 554, 569, 583A, 583B, 583C, 596, and 944 on Moffett Field, CA
09/29/11Site-wide Vapor Intrusion Sampling and Analysis Work Plan for Response Action Tiering
03/26/12Final Technical Memorandum In Situ Anaerobic Biotic/Abiotic Treatability Study Installation Restoration Site 28 on Moffett Field (excluding Appendices F and H)
04/01/122011 Regional Groundwater Remediation Program Progress Report - Restoration Program, NASA Ames Research Center
04/13/122011 Annual Groundwater Report for Moffett Field Site 26 EATS Area and Site 28 WATS Area (excluding Appendices C, D, E)
04/13/122011 Annual Progress Report for former Fairchild facilities - Bldgs 1-4, 9, 18, 19, 20
04/13/122011 Annual Progress Report for Former Intel- Mtn View facility - 365 E. Middlefield Road
04/13/122011 Annual Progress Report for Former Raytheon - 350 Ellis Street
04/13/122011 Annual Progress Report for MEW Regional Groundwater Remediation Program (excluding Appendices B and F)
04/13/122011 Annual Progress Report for Vishay/SUMCO/Schlumberger 405/425 National Avenue
04/16/122011 Annual Vapor Intrusion Progress Report for MEW and Moffett Field Areas
05/17/12Navy's Air Sampling Work Plan for Vapor Intrusion Tier Response Evaluation at Moffett Field
06/27/12Final Work Plan Supplemental Investigation for Building 88 and Traffic Island Areas Installation Restoration Site 28 on Moffett Field
02/22/13Indoor Air Sampling Report – Former Fairchild properties – Google Quad – 369-399 N Whisman Rd and 464 Ellis St
03/01/132012 − 2013 Groundwater Results - TCE in Shallow Groundwater
04/01/132012 Annual Progress Report for Vishay/SUMCO/Schlumberger 405/425 National Avenue
04/01/132012 Regional Groundwater Remediation Program Progress Report - Restoration Program, NASA Ames Research Center
04/09/132012 Annual Progress Report for former NEC/Renesas 501 Ellis Street
04/09/132012 Annual Progress Report for SMI Holding LLC's Facility
04/12/132012 Annual Progress Report for Former Intel- Mtn View facility - 365 E. Middlefield Road
04/15/132012 Annual Progress Report for former Fairchild facilities - Bldgs 1-4, 9, 18, 19, 20 (excluding Appendix B)
04/15/132012 Annual Progress Report for Former Fairchild Facilities - Bldgs 13, 19 and 23 (excluding Appendix B)
04/15/132012 Annual Progress Report for MEW Regional Groundwater Remediation Program
04/17/132012 Annual Groundwater Report for Installation Restoration Sites 26 and 28 (excluding Appendix C)
07/30/13EPA Comments on Grab-Groundwater Assessment and Proposed Well Installation Report and Next Steps for Evaluation of Hydraulic Containment - Middlefield-Ellis-Whisman (MEW) Superfund Study Area, Mountain View and Moffett Field, CA
08/13/13Work Plan for Pilot Study Data Collection - 401 National Avenue, Mountain View, California
08/15/13Draft Pilot Study Design and Implementation Work Plan, Evandale Avenue Sources, Middlefield-Ellis-Whisman - Regional Groundwater Remediation Program
09/12/13Final Grab-Groundwater Assessment and Proposed Well Installations
09/30/13TCE Groundwater and Soil Gas Sampling Results Map for the South of 101 area in September 2013
10/25/13Subsurface Investigation Report for Moffett Gateway/Former Vector Control Yard property – 750 Moffett Blvd, Mountain View, CA
11/14/13Final Pilot Study Design and Implementation Work Plan - Evandale Avenue Sources
12/01/13Draft Work Plan for the Northernmost A2/B1-Aquifer Plume Definition Assessment
12/10/13Draft Work Plan Phase for In Situ Bioremediation – Former Fairchild Building 9
03/21/14Workplan for Groundwater Remediation Optimization for 355/365 and 401 East Middlefield Road, Mountain View

Top of page

Community Involvement

Public Meetings: A community advisory group, the MEW Community Advisory Board, meets regularly to learn about and discuss MEW investigations 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.

Top of page

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
Hours:
Monday-Thursday: 10 am to 9 pm
Friday and Saturday: 10 am to 6 pm
Sunday: 1 pm to 5 pm
650-903-6887

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

Top of page

Contacts

EPA Site Manager
Alana Lee
Penny Reddy
415-972-3141
415-972-3108
Lee.Alana@epamail.epa.gov
Reddy.Penny@epamail.epa.gov
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Alejandro Diaz
415-972-3242
1-800-231-3075
Diaz.Alejandro@epamail.epa.gov
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
415-947-8701
r9.info@epa.gov
State Contact
PRP Contact
Community Contact
Lenny Siegel
650-961-8918
LSiegel@cpeo.org
Center for Public Environmental Oversight,
a Project of the Pacific Studies Center,
278A Hope Street
Mountain View, CA 94041
Other Contacts
After Hours (Emergency Response)
US EPA
(800) 424-8802

Top of page



Jump to main content.