The Pacific Gas and Electric Company (PG&E) Topock Compressor Station (Station) compresses natural gas so it can be transported through pipelines to PG&E's customers in northern and central California. Historical waste management practices have resulted in potential contamination to both soil and groundwater. From 1951 to 1985, PG&E used hexavalent chromiumHexavalent chromium is a form of chromium. Chromium is a metal naturally found in rocks, soil, and the tissue of plants and animals. Hexavalent chromium can be found naturally at low concentrations, but it is also used in industrial products and processes and is a known carcinogen. On May 28, 2014, the California Department of Public Health adopted a new California drinking water standard at 10 parts per billion for hexavalent chromium. to prevent rust in its cooling towers. From 1951 to 1964, untreated wastewater from the cooling towers was discharged into percolation beds in Bat Cave Wash, a normally dry wash next to the Station. Beginning in 1964, PG&E treated the wastewater to remove hexavalent chromium. The treated wastewater was discharged into Bat Cave Wash until 1968, and subsequently was discharged into an onsite injection well. Over time, PG&E installed a series of lined evaporation ponds for wastewater disposal. In 1985, PG&E stopped using the chromium-based additive and switched to a phosphate-based solution.

  • A tracer study and a pumping test were initiated in mid-June 2021 to obtain additional information about the subsurface in the vicinity of the Topock Compressor Station. This information will assist in refining the groundwater model that will be used to assess the performance of the groundwater remedy. DTSC conducted a CEQA review of the proposed study, and prepared/adopted an addendum to the groundwater SEIR on April 8, 2021.
  • Phase 1 construction of the groundwater remedy began October 2, 2018 and is anticipated to be completed in 2021. Heavy construction was completed in the Spring of 2021. System integration and functional testing is planned for the second and third quarters of 2021, with remedy startup in the fall of 2021. Interim Measures 3 (IM-3) groundwater extraction and its associated treatment system will be turned off when the remedy is started.
  • The Soil RFI/RI reporting began concurrently with the soil Risk Assessment. The revised RFI/RI report was submitted on May 31, 2021 for review and comment. It is anticipated to be completed in early 2022.
  • The DTSC February 2021 Fact Sheet - Community Update: Pacific Gas & Electric Company (PG&E) Topock Compressor Station, Cleanup Program Update is now available to view here.
  • PG&E has submitted monthly groundwater remedy construction progress reports to the agencies since November 2018. The latest monthly report can be found here.
  • Due to the COVID-19 pandemic, a temporary shutdown of the groundwater remedy construction activities occurred from April 1, 2020 to May 11, 2020. Agencies' direction to PG&E to shut down can be found here.
  • As required by the Land Use Covenant entered by PG&E and DTSC, a Soil Management Plan (SMP) for the Compressor Station was submitted on November 1, 2019. 
  • On October 30, 2018, DOI directed PG&E to prepare a Draft Engineering Evaluation/ Cost Analysis (EE/CA). The purpose of an EE/CA is to evaluate the need for a non-time critical removal action (NTCRA) on federal lands or at locations where contamination has the potential to migrate to federal lands. The public comment period for the EE/CA occurred from June 3, 2020 to August 5, 2020. The draft EE/CA can be found here. The DOI has responded to comments received and issued responses to comments on April 23, 2021. DOI prepared and approved a decision document, called an Action Memorandum, for the NTCRA on October 12, 2021. The Action Memorandum, along with a Responsiveness Summary and the Final EE/CA can be found here. A fact sheet on the EE/CA can be found here
  • A Fact Sheet - Community Update: Pacific Gas & Electric Company (PG&E) Topock Compressor Station, Environmental Investigation Update was prepared in April 2018 and can be found here.
  • Based on the Final Design, the Department of Toxic Substances Control (DTSC)The department within the California Environmental Protection Agency in charge of the regulation of hazardous waste from generation to final disposal. DTSC oversees the investigation and cleanup of hazardous waste sites. prepared a Subsequent Groundwater Remedy Environmental Impact Report (SEIR). The April 24, 2018 certified Final SEIR evaluated potential environmental impacts resulting from design details of the selected groundwater remedy (in situ TreatmentTreatment of contamination in place. with Freshwater FlushingMoving of fresh water through the well system to push the plume through an In-Situ Reduction Zone located along National Trails Highway.) that were modified since the approval of the conceptual Groundwater Remediation Project in the 2011 Final Groundwater Remedy EIR and the 2013 Addendum to the EIR.
  • The DTSC certified the Final SEIR on April 24, 2018, and conditionally approved the groundwater remedy design on April 24, 2018. Construction of the final groundwater remedy system began October 2, 2018.
  • The First Addendum to the Corrective Action Consent Agreement (CACA) was completed on January 25, 2018.
  • On June 20, 2017, DTSC and DOI determined that the Soil RFI/RI field work was completed. PG&E proceeded in preparing the Soil Human Health and Ecological Risk Assessment (HHERA) in accordance with the approved work plan and addendum. The Final Soil HERRA Report was published in October 2019. An Errata was submitted on February 19, 2020. The Soil HERRA and Errata were accepted on May 29, 2020 by DTSC and DOI. 
  • The Basis of Design/Final (100%) Design Report was submitted by PG&E on November 18, 2015. An errata was submitted on November 18, 2016 and an addendum to the flow and solute transport model was submitted on January 9, 2017. An addendum to the SMP was submitted on May 28, 2019. On October 8, 2020, PG&E submitted, and DTSC approved, an updated Table to the SMP that incorporated revised values from the Soil HHERA.