What's New

Five-Year Review

The U.S. Department of the Interior (DOI), in cooperation with the California Department of Toxic Substances Control (DTSC), is beginning a Five-Year Review process under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) that will review the groundwater remedy implemented at the Topock Compressor Station in San Bernardino County, California.

The selected remedy for groundwater includes the use of in-situ treatment with fresh water flushing for groundwater contamination associated with Solid Waste Management Unit (SWMU) 1/Area of Concern (AOC) 1 and AOC 10.

The purpose of the Five-Year Review is to ensure that the implemented remedy functions as intended and is protective of human health and the environment. Five-Year Reviews will continue for the life of the site until hazardous substances, pollutants, or contaminants no longer remain on-site at levels that do not allow for unlimited use and unrestricted exposure.

The Public Notice for the First Five-Year Review of the Groundwater Remedy can be found here.

More information on the Five-Year Review process can be found on the Fact Sheet here.

Phase 1 of Construction of the Final Groundwater Remedy is Completed and the Remedy is Operating

Click here for the current construction activities. 

Implementation of the Final Groundwater Remedy will adhere to the Final Groundwater Design. The conditional approvals of the final design can be viewed here. The Final Groundwater Remedy Design document can be downloaded here.

Phase 1 of remedy construction, which began on October 2, 2018, is now complete. It includes the National Trails Highway (NTH) In-situ Reactive

Zone (IRZ) with 22 remediation wells (for injection and/or extraction) and a robust network of 75 monitoring wells (for measuring water levels and quality), as well as a network of over 74,000 linear feet of water conveyance piping and 41,000 feet of electrical conduits that connect the remediation wells to the power supply system, the carbon amendment building, and the produced water conditioning system. 


All systems and components were integrated and tested to make sure they function properly. On December 22, 2021, PG&E turned on the NTH IRZ remedy treatment system. During the start-up process, water level and groundwater chemistry are closely monitored and adjusted to ensure the best possible treatment conditions. PG&E and the regulatory agencies will continue to monitor and adjust the initial operation of the NTH IRZ.


In parallel, PG&E commenced Phase 2 of construction in March 2022, as shown in the summary schedule which can be downloaded here.

Soil Non-Time Critical Removal Action (NTCRA)

On October 30, 2018, U.S. Department of the Interior (DOI) directed PG&E to prepare a Draft 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 in soil has the potential to migrate to federal land. A fact sheet on the EE/CA can be found here. The public comment period for the EE/CA occurred from June 3, 2020 to August 5, 2020. In parallel, consultation with nine Tribes occurred through August 21, 2020. DOI has responded to comments received and issued responses to comments on April 23, 2021, and directed PG&E to finalize the EE/CA. The final EE/CA can be found here

On October 12, 2021, DOI selected a removal action of excavation of contaminated soil and debris at fourteen target action areas within the Topock Site.  The removal action consists of mechanical separation/size separation of rocks, debris, and soil; and disposal of the contaminated soil and debris in approved and permitted landfills. DOI’s decision is documented in an Action Memorandum, which can be downloaded here. Subsequently, on October 29, 2021, PG&E submitted a draft Soil NTCRA work plan to present details about PG&E’s plan to perform the removal action. The work plan was sent to the Consultative Working Group (CWG) for review and comment. In parallel, BLM consulted with the Tribes on the draft work plan. Comments were received in December 2021. DOI has responded to comments received and issued responses to comments in March 2022, and DOI has directed PG&E to finalize the Soil NTCRA work plan in May 2022. The final Soil NTCRA Workplan can be found here. The Response to Comments Table can be downloaded here. DOI conditionally approved the Soil NTCRA Workplan on June 27, 2022.


Soil Risk Assessment Completed and Soil RFI/RI Reporting is in Progress

The human health and ecological risk assessment (HHERA) for soil began on June 20, 2017 upon completion of the soil investigation field work. The HHERA assessed potential human health and ecological risks based on soil sampling data. This information will assist risk management decisions on the need for soil remediation, if any. The Soil HHERA report was submitted to agencies on October 18, 2019, and an errata was submitted on February 19, 2020. The Soil Risk Assessment Report plus errata were approved on May 29, 2020. The report can be downloaded here

Findings and conclusions of the soil investigation field work and the conclusions from the Risk Assessment are presented in the Soil Resource Conservation and Recovery Act (RCRA) Facility Investigation/Remedial Investigation (RFI/RI) Report (also called the RFI/RI Volume 3 Report). PG&E submitted a revised Soil RFI/RI Volume 3 report on May 31, 2021 for review and comment. The Soil RFI/RI Report is anticipated to be completed in 2022.

Termination of Interim Measure (IM) No. 3

To minimize any impacts from the IM extraction on the development of the NTH IRZ, PG&E turned off the IM extraction wells on December 21, 2021, and began preparing the IM for lay-up. The preparation for lay-up was completed on March 21, 2022, and IM No. 3 is put in lay-up condition on March 22, 2022. When the IM is in a lay-up condition, the system will be left in a safe, secure, and preserved state and will not operate again until agency approval is received for decommissioning and removal of the system.

Consultative Workgroup (CWG) Meeting

The Consultative Workgroup (CWG) is a specific group of key governmental agencies, stakeholders and Tribes established in 2000 to facilitate participation in the Site investigation and remediation process. The CWG usually meets quarterly. A CWG meeting was held on June 22, 2022.

Technical Workgroup (TWG) Meeting

The Technical Workgroup (TWG) was established as a subgroup of the Consultative Workgroup (CWG) for technical experts to deliberate on various scientific aspects of the Project and remediation issues as needed. A TWG meeting was held on May18, 2022.

Clearinghouse Task Force (CTF) Meeting

The CTF is a small group of representatives from State and Federal agencies, key stakeholders and Tribes formed to strategize and develop processes and tools to improve communications and enhance stakeholder understanding of Project and regulatory information. CTF meetings generally occur as needed throughout the year.

DTSC January 2022 Fact Sheet Available

DTSC provides periodic updates on the progress of the site investigation and cleanup efforts in periodic Community Updates/ Fact Sheets. The DTSC January 2022 Fact Sheet - Community Update for the PG&E Topock Compressor Station is now available to view here.

An Aquifer Test at TW-01

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 assisted in refining the groundwater model that will be used to assess the performance of the groundwater remedy. DTSC conducted a California Environmental Quality Act (CEQA) review of the proposed study, and prepared/adopted an addendum to the groundwater SEIR on April 8, 2021. The test was terminated on December 13. 2021.