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

Teledyne Semiconductor

EPA #: CAD009111444

State: California(CA)

County: Santa Clara

City: Mountain View

Congressional District: 14

Other Names:

Bulletin Board

On 10/13/17, this website will no longer be updated. Site information will be migrated to the new web page at: http://www.epa.gov/superfund/teledyne .
EPA appreciates your patience through this transition. If you have questions, please contact EPA staff listed below.

Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 10/15/84

Final Date: 07/22/87

Deleted Date:

Teledyne Semiconductor has operated as a semiconductor manufacturer at this 1-acre site since 1962. In 1982, Teledyne reported to the California Regional Water Quality Control Board (CRWQCB) that soil and groundwater were contaminated with solvents from an underground solvent storage tank. The State inspected the site and found that contaminants had migrated north of the site and affected approximately 50 private domestic wells. Furthermore, contaminated groundwater that migrated north from another NPL site, Spectra-Physics, Inc., merged with the contaminated plume of the Teledyne site. The two firms are cleaning up the sites jointly. These sites are among the 28 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 have contaminated a common groundwater basin. Although the sites are listed separately on the NPL, the EPA intends to combine cleanup activities at some of the sites as part of an area-wide approach to the contamination. The site is located in a densely populated, urban area. Approximately 189,000 people live within a 3-mile radius of the site. The distance from the site to the nearest residence is 200 feet.

Top of page

Contaminants and Risks

Contaminated Media
  • Groundwater
  • Soil and Sludges

Soil was contaminated with volatile organic compounds (VOCs). Groundwater is contaminated with VOCs. Drinking water is not affected by this contamination. Drinking water for this area comes from the Hetch Hetchy Reservoir in the Sierra Nevada, not from regional groundwater.

Top of page

Who is Involved

This site is being addressed through Federal, State, and potentially responsible parties' actions.

Top of page

Investigation and Cleanup Activities

Cleanup Ongoing

Since the late 1980s, Teledyne and Spectra-Physics have operated onsite and offsite groundwater extraction wells to remove TCE and hydraulically control the groundwater plume. In 2003, most of the groundwater extraction system was shut down due to decreased pollutant mass removal efficiency. In 2003, the Responsible Parties (RPs) pilot-tested and monitored natural attenuation for two years and concluded that this approach would not attain cleanup standards in a reasonable time.

In 2006, the Regional Board directed the RPs to re-characterize the Teledyne source property using high-resolution investigation technology to help focus further cleanup efforts. This work discovered and delineated previously unknown TCE hot spots at the site. In 2011, the dischargers pilot-tested an “in situ” method: enhanced bioremediation with recirculation. This involved injecting a carbohydrate solution as a food source for naturally occurring microbes, adding a microbial solution to accelerate the bioremediation process, and re-circulating the carbohydrate/microbe solution through a system of extraction and injection wells. The microbes consumed the carbohydrate solution and destroyed the TCE in place, creating harmless dechlorination byproducts such as carbon dioxide and salts.

The pilot study reduced groundwater-TCE levels from as high as 80,000 parts per billion (ppb) to below 100 ppb, and in some wells to less than 5 ppb (the cleanup standard). This work is ongoing.

Top of page

Cleanup Results to Date

Construction of all cleanup remedies is complete. Contaminated soil has been removed. Ongoing extraction and treatment of the groundwater continues to reduce the potential for exposure to contaminants at the Teledyne Semiconductor site. Groundwater treatment will continue until established cleanup goals are met.

The Fourth Five-Year Review was completed in Sept. 2014, concluding that the vapor intrusion indoor air investigation needs to be completed before a “protectiveness determination” can be made.

The following issues and recommendations were identified in the report:

Issue #1 – The performance of the selected remedy in the Record of Decision, groundwater extraction and treatment, has declined and new remedial actions are being investigated.

Recommendation – Complete a Record of Decision Amendment or prepare an Explanation of Significant Differences selecting new remedial actions and including updated institutional controls.

Issue #2 – The Five-Year Review vapor intrusion evaluation indicated that the subsurface-to-indoor air pathway is a concern at the site.

Recommendation – Continue to monitor and provide mitigation for vapor intrusion, including step-outs to lower concentration areas of the shallow TCE groundwater plume.

The Five-Year Review further stated the following:

A protectiveness determination of the remedy at the Teledyne Semiconductor and Spectra-Physics, Inc. Joint Superfund Sites cannot be made at this time until further information is obtained. Additional vapor intrusion assessments must be conducted to determine if indoor air pathways are complete. When unacceptable levels are encountered in a particular building, mitigation plans are developed and implemented to ensure that levels of volatile organic compounds (VOCs) in indoor air are protective. It is expected that these actions will take approximately two years to complete, at which time a protectiveness determination can be made. To be protective in the long-run, a new remedy should be selected due to the declining effectiveness of the existing remedy.

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.

Online information about the PRPs for the site is not yet available.

Top of page

Documents and Reports

Hide details for Community InvolvementCommunity Involvement
01/01/14Residential Indoor Air Sampling Outreach Letter
05/01/14Sample Letter (VI Requiring Mitigation) - Indoor Air Sampling Results for Residential Building #XX, Mountain View, California
05/01/14Sample Letter (VI Under Screening Levels) - Indoor Air Sampling Results for Residential Building #XX, Mountain View, California
06/01/15Access for Indoor Air Sampling Outreach Letter
07/01/15Outreach Material Letter to Residences Who Decline Air Sampling
11/15/15Winter 2015 Door-to-Door Outreach Letter for Indoor Air Sampling (English and Spanish)
Hide details for Fact SheetsFact Sheets
12/01/13South Bay Groundwater Sites - Vapor Intrusion Evaluations (Dec. 2013 Update)
04/01/14Vapor Intrusion Mitigation Fact Sheet
07/01/17New Groundwater Cleanup Activities Greatly Reduce Contamination as Indoor Air Investigation Continues
Hide details for MapsMaps
08/30/10Site Map Showing Groundwater TCE Isoconcentrations - Commercial
01/08/14Site Map Showing Residential Buildings and the Underlying Contamination Area (Included In The Work Plan Addendum)
03/20/14Vapor Intrusion Study Area Map
Hide details for Records of DecisionRecords of Decision
03/22/91Record of Decision
Hide details for Technical DocumentsTechnical Documents
09/29/99First Five Year Review Report
01/01/01Off-Property Source Areas
09/30/04Second Five Year Review Report
09/30/09Third Five Year Review Report
12/03/13EPA Region 9 Guidelines and Supplemental Information Needed for Vapor Intrusion
Evaluations at the South Bay National Priorities List (NPL) Sites - Letter
02/19/14Approval of Work Plan Addendum for Vapor Intrusion Evaluation of Residential Buildings in the Off-Property Study Area - Letter
05/24/14Data Summary for Residential Indoor Air Sample Results (May 2014)
07/09/14EPA Region 9 Response Action Levels and Recommendations to Address Near-Term Inhalation Exposures to TCE in Air from Subsurface Vapor Intrusion
09/23/144th Five-Year Review Report
10/02/14Site-Wide VI & GW Investigative/Remedial Path Forward: Minutes of October '14 meeting bewtween EPA, RPs & the State
10/21/14Work Plan Addendum for Vapor Intrusion Evaluation of the Former Teledyne Semiconductor Building Located at 1300 Terra Bella Avenue,
05/22/15Soil Vapor Extraction System Construction Completion Report and Operations and Maintenance (O&M) Schedule
01/01/16Inhalation Exposure Screening Levels (SLs): VOCs at Vapor Intrusion Sites in California
02/04/164th Quarter 2015 – VI Evaluation Data Submittal
02/10/16Work Plan for Third Injection Event - Full-Scale Enhanced Reductive Dechlorination (ERD) Treatability Study
02/28/16Draft Revised Focused Feasibility Study, Former Spectra-Physics Lasers, Inc. and Former Teledyne Semiconductor Sites, Mountain View, California (No Appendices)
05/11/16Soil Gas Investigation Work Plan for the Former Semiconductor Property - Former Spectra-Physics Lasers, Inc. and Former Teledyne Semiconductor Sites

Top of page

Community Involvement

Public Meetings:

Top of page

Public Information Repositories

The public information repositories for the site are at the following locations:

California Regional Water Quality Control Board
1515 Clay Street
Suite 1400
Oakland, CA 94612

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


EPA Site Manager
Angela Sandoval
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Alejandro Diaz
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
Roger Papler
California Regional Water Quality Control Board
1515 Clay Street
Suite 1400
Oakland, CA 94612
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

Top of page

Jump to main content.