Soil Cleanup Activity Overview

Time Critical Removal Action
Non-Time Critical Removal Action
RCRA Facility Investigation/Remedial Investigation
Human and Ecological Risk Assessment
Coordination with Tribal Nations and Stakeholders

Environmental investigation and groundwater monitoring have been under way at the Topock Project Site since 1997. The California 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. and the U.S. Department of the Interior (DOI)The United States department charged with conservation and development of natural resources. The U.S. Department of the Interior uses sound science to manage and sustain America’s lands, water, wildlife, and energy resources, honors our nation’s responsibilities to tribal nations, and advocates for America’s island communities. are the lead governmental agencies overseeing Pacific Gas and Electric Company’s (PG&E's) actions to protect the Colorado River and to clean up soil and groundwaterWater beneath the Earth’s surface that flows through soil and rock openings (aquifers). contamination in the vicinity of the PG&E Topock Compressor Station (Station).

The Station has been in operation since 1951. Historical waste management practices have resulted in potential contamination to both soil and groundwater. PG&E is conducting soil investigation and remedial activities at the Site under the Resource Conservation and Recovery Act (RCRA)A 1976 amendment to the first federal solid waste legislation, the Solid Waste Disposal Act of 1965. In RCRA, Congress established initial directives and guidelines for U.S. EPA to regulate and manage solid waste, including hazardous waste. RCRA established a regulatory system to track hazardous substances from the time of generation to final disposal. The law requires safe and secure procedures to be used in treating, transporting, storing and disposing of hazardous wastes. RCRA was designed to prevent new, uncontrolled hazardous waste sites. and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)Commonly known as Superfund, this law created a tax on the chemical and petroleum industries and provided broad federal authority to respond directly to releases or threatened releases of hazardous substances that may endanger public health or the environment. CERCLA established prohibitions and requirements concerning closed and abandoned hazardous waste sites; provided for liability of persons responsible for releases of hazardous waste at these sites; and established a trust fund to provide for cleanup when no responsible party could be identified. The law authorizes two kinds of response actions: Short-term removals, where actions may be taken to address releases or threatened releases requiring prompt response. Long-term remedial response actions, that permanently and significantly reduce the dangers associated with releases or threats of releases of hazardous substances that are serious, but not immediately life threatening., pursuant to agreements with DTSC and DOI, respectively.

Through an initial site review process, areas of concern (AOCs) and solid waste management units (SWMUs) that managed, or potentially managed hazardous material or waste were identified for further evaluation. The soil medium is currently in the RCRA Facility Investigation/Remedial Investigation (RFI/RI)An investigation that occurs in the corrective action process following a Facility Assessment under RCRA and/or a Site Inspection under CERCLA. It is an in-depth study designed to gather data needed to determine the nature and extent of contamination at a site. phase of the investigation process. Soil and related investigation activities covered 15 areas located outside the Station fence line (see figure below) and 27 areas located inside the Station fence line (see figure below). The perimeter areas adjacent to the Station fence line and the storm drains leading from the Station to areas outside the fence line are also included in the investigation.

Soil sampling and related Soil Investigation field work was completed between December 2015 and March 2016, January through March 2017, and the latter part of April 2017. That work fulfilled requirements of the Topock Soil Facility Investigation/ Remedial Investigation (RFI/RI) Work Plan and Data Gap Work Plans #1, #2, and #3. Field work included:

Collection of soil samples at 364 locations.
Trenching of 15 locations to evaluate possible contamination.
Collection of sediment and pore water samples from 10 locations at the edge of the Colorado River by the East Ravine.

The field work was conducted in phases and in an iterative process. After sample collection was completed, results were evaluated by DTSC, the U.S. Department of the Interior (DOI), and PG&E to determine data gaps and if additional data collection was needed to complete the Soil Investigation and evaluate potential next steps. The agencies and PG&E balanced the data collection necessary with Tribes' request to minimize site intrusion by maximizing the use of archived samples and collection of samples from existing locations.

On June 20, 2017, PG&E began the risk evaluation process per the approved Risk Assessment Work Plan and addendum. The risk assessment evaluated potential human health and ecological risks based on soil sampling data. This information will assist risk management decisions on the need for soil remediation. The Soil Risk Assessment Report plus errata were approved on May 29, 2020. The report and errata can be downloaded here.

Concurrently, the preparation of the Soil RFI/RI Report (also called the RFI/RI Volume 3 Report) has begun. The Soil RFI/RI Report will present the findings and conclusions of the soil investigation field work and the conclusions from the Risk Assessment. The Final Soil RFI/RI Report was submitted to DTSC and DOI on October 2, 2023. DTSC accepted the final report on June 10, 2024. DOI provided concurrence with DTSC’s acceptance on June 25, 2024. The Final Soil RFI/RI Report can be downloaded here.

Due to timing differences in the investigation and reporting of the resulting data, the Final RFI/RI report has been divided into three separate volumes:

Volume 1 - Site Background and History
Volume 2 – Hydrogeological Characterization and Results of Groundwater and Surface Water Investigation
Volume 3 - Soil Characterization Results

Volumes 1 and 2 are discussed in the Groundwater Cleanup – RCRA Facility Investigation/Remedial Investigation pages.

The Volume 3 Report includes the final soil characterization results (including a soil risk assessment, which is a study prepared to assess health and environmental risks due to potential exposure to hazardous substances that might be in the soil) to complete the RFI/RI requirements for the Site. The first phase of soil investigation in areas outside of the Station was completed in 2008. Soil data have been reviewed, and data gaps have been identified. A Draft Soil RFI/RI Work Plan, which describes the additional data needed to address the identified data gaps at the Site, was prepared and submitted on May 6, 2011. A revised Soil Work Plan was submitted on January 14, 2013, which proposed additional soil investigation for all areas of the Site. Pursuant to the California Environmental Quality Act (CEQA), DTSC evaluated the environmental impacts associated with the soil investigation in the Final Soil EIR. DTSC filed a determination and certified the Final Soil EIR on August 24, 2015 along with the approval of the Final Work Plan. DOI also approved the Soil RFI/RI Work Plan on August 24, 2015. PG&E began the soil field investigation on October 29, 2015 and completed it in April 2017.The draft Soil RFI/RI Report was submitted in December 2019. It was then revised based on agencies’ comments and re-submitted on May 31, 2021. All comments received were responded to and sent for review on December 20, 2021. Subsequently, four meetings were held in February 2022 to resolve a subset of the responses. Revised text of key report sections was prepared and sent for review in September 2022. Revision of the report based on comments received is complete, and the final RFI/RI Volume 3 Report was submitted to DTSC and DOI on October 2, 2023. DTSC accepted the final report on June 10, 2024. DOI provided concurrence with DTSC’s acceptance on June 25, 2024.

RFI/RI Volume 1 and 2 (and its addendum if applicable) can be found in the Information Repositories and the Document Library. RFI/RI Volume 3 can be found in the Document Library, and will be made available in the Information Repositories.

(Click on images above for larger view)

Time-Critical Removal Action

On June 24, 2009, the DOI directed PG&E to remove debris that had been deposited within a ravine south of the Topock Compressor Station (Station) through the issuance of the Area of Concern (AOC)Areas outside of the source remediation site that are being evaluated and may be contaminated due to past practices and/or proximity to the source site. These areas are subject to the overall site’s environmental investigation to determine if they will also need to be remediated. 4 Debris Ravine Time-Critical Removal Action (TCRA)A time sensitive action to stabilize and mitigate the threat of release of contaminated material. It is not intended to substitute for any remedial activities or be the final remedy. Memorandum. The TCRA was necessary to control the potential migration of contamination from PG&E to the Havasu Wildlife Refuge property. The debris was deposited as a result of PG&E's historical waste disposal practices and contains construction debris, burn ash, and other miscellaneous Topock Project Site (Site)-related items. The debris and the underlying soil were determined to contain elevated levels of metals, polychlorinated biphenyls, dioxins, and furans. Work planning and consultation for the removal activities immediately ensued, and DOI approved PG&E’s Work Plan on December 15, 2009. The AOC 4 Debris Ravine TCRA field activities were performed from December 2009 through December 2010 in compliance with the DOI TCRA Work Plan. During this time, approximately 11,800 tons of waste and soil was removed from the AOC 4 Debris Ravine. On March 15, 2011, PG&E completed the Implementation Report for the Time-Critical Removal Action at AOC 4, Pacific Gas and Electric Company Topock Compressor Station, Needles, California.

Non-Time Critical Removal Action

Similar to the Time Critical Removal Action (TCRA) at AOC 4, areas were identified through the soil investigation and the Human Health and Ecological Risk Assessment that contamination has either impacted or may potentially impact federal lands. As a result, DOI contemplated a potential removal action for the protection of the wildlife refuge. On October 30, 2018, DOI directed PG&E to prepare a draft Soil 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 land. The draft EE/CA, which was submitted on May 29, 2020, considered a range of options including no action, separation of soil by size with soil washing, or complete removal and disposal of the contaminated soil. The public comment period for the draft EE/CA was held from June 3, 2020 to August 5, 2020. DOI issued responses to comments on April 23, 2021 and directed PG&E to revise the draft EE/CA. 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.

In the Action Memorandum, DOI directed PG&E to prepare a work plan to conduct the NTCRA. A draft plan was submitted in October 2021 for DOI’s review. DOI solicited comments on the draft work plan from DTSC, Tribes, and stakeholders. Comments meetings were held in April and May 2022 to discuss the responses. A final Soil NTCRA Work Plan was submitted on June 17, 2022. The final work plan can be found here. The Response to Comments Table can be downloaded here. DOI approved the final Soil NTCRA work plan on June 27, 2022.

PG&E commenced the NTCRA soil removal action on July 25, 2022. Work was completed in February 2024 and approximately 34,706 cubic yards of contaminated soil/debris was removed.

Pursuant to the final Soil NTCRA Work Plan, PG&E is preparing a Completion Report for submittal to DOI following completion of the field implementation.

Resource Conservation and Recovery Act (RCRA) Facility Investigation/Remedial Investigation (RFI/RI)

PG&E conducted supplemental soil investigation field work as necessary to complete the third Volume of the Resource Conservation and Recovery Act Facility Investigation/Remedial Investigation (RFI/RI) report. See the RFI/RI page under Groundwater for discussion of Volumes 1 and 2. The purpose of the soil investigation was to collect data to support the soil risk assessment, characterize the nature and extent of soil contamination, and to evaluate potential for soil contamination to affect the groundwater. The information gathered will inform the soil remedy selection if needed.

The soil investigation was conducted in phases and in an iterative manner. The first phase of soil investigation in areas outside of the Station was completed in 2008. Soil data have been reviewed, and data gaps have been identified. A Draft Soil RFI/RI Work Plan, which describes the additional data needed to address the identified data gaps at the Site, was prepared and submitted on May 6, 2011. Comments were received from Tribal Nations and agencies. A revised Soil RFI/RI Volume I Work Plan was submitted on January 14, 2013. An addendum to the Soil RFI/FI Work Plan Volume I work plan was submitted May 30, 2014. Pursuant to the California Environmental Quality Act (CEQA)A law mandating review of environmental impact of governmental action. It requires that public agencies study the significant environmental effects of proposed activities and that the public be informed and allowed to comment on project decisions. DTSC evaluated the environmental impacts associated with the soil investigation in the Final Soil EIR, DTSC filed a determination and certified the Final Soil EIR on August 24, 2015 along with the approval of the Final Work Plan. DOI also approved the Soil RFI/RI Work Plan on August 24, 2015. PG&E began the soil field investigation on October 29, 2015. The results of the soil sampling events are evaluated for data gaps and to identify additional data needed. Field work was guided by the approved Work Plan and the subsequent data gap work plans (#1, 2, and 3). All field work was completed in April 2017. The results of the investigation were used to support the soil risk assessment and the data will be included in the Volume 3 - RFI/RI Report on Soil Characterization. PG&E submitted the final Soil RFI/RI Volume 3 report on October 2, 2023. DTSC accepted the final report on June 10, 2024. DOI provided concurrence with DTSC’s acceptance on June 25, 2024. The RFI/RI Volume 3 is available in the Document Library, and will be made available in the Information Repositories.

Human and Ecological Risk Assessment

The Risk Assessment Work Plan was submitted on August 25, 2008. An addendum was submitted on February 4, 2009. On September 19-20, 2013, DTSC, DOI, PG&E, and Tribes met to discuss amendments to the Soil Risk Assessment Work Plan. DTSC approved the Soil Risk Assessment Work Plan and addendum on February 4, 2009 and DOI approved on February 5, 2009. A Final Risk Assessment Work Plan Addendum II was submitted on June 29, 2015 and contains updated information relevant to soil risk assessment activities and evaluation based on comments received by Tribes, agencies, and stakeholders. DTSC conditionally approved the Soil Risk Assessment Addendum II on August 31, 2015 (clarified on September 15, 2015) and DOI conditionally approved the Addendum 2 on September 8, 2015. Upon completion of the soil investigation field work and discussion of soil data, PG&E began the soil risk evaluation on June 20, 2017. The Soil Risk Assessment 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 approved Soil Risk Assessment Report and its errata can be found here.

Pursuant to the final Soil NTCRA Work Plan, an addendum to the Soil Risk Assessment is being conducted following completion of the NTCRA.

Coordination with Tribal Nations and Stakeholders

Due to the diverse interests of this project, regulatory agencies, Tribal Nations, and other stakeholders meet regularly to exchange information and gather input as part of the Consultative Workgroup (CWG)A group consisting of stakeholders and multiple state and federal agencies that have an interest in the cleanup of a contaminated site, and meet regularly to discuss actions and make decisions., the Technical Workgroup (TWG)A focused stakeholder subgroup of the Consultative Work Group (CWG) where various stakeholders and their consultants discuss technical project related issues in greater detail which are then reported back to the CWG., the Clearinghouse Task Force (CTF)A group formed to develop and implement processes and tools to improve communications and enhance Topock stakeholder understanding of project technical and regulatory information., and the Topock Leadership Partnership (TLP)Forum that enables senior officials to provide input to the regulatory agencies on the direction of actions necessary to complete the Topock project..

The CWG, established by DTSC in March 2000, consists of agencies, Tribal Nations, and other entities that have an interest in protecting the Colorado River and the surrounding environment. The goal of the CWG is to allow timely input on proposed activities and decisions to be made. In addition to the CWG, the regulatory agencies and PG&E occasionally conduct independent outreach to the public, governmental representatives (including federal, state, county, and city elected officials and staff), and leaders and staff of Tribal Nations. The CWG generally meets about three times per year.

The TWG is a subgroup of the CWG. The TWG meets to deliberate on specific technical issues of the Project in greater detail and then report back to the CWG with the results. All CWG members are invited to send staff to participate in the TWG. Technical areas of discussion include geochemistry, hydrogeology, statistics for investigation, modeling and engineering design, human health and ecological risk assessments, remediation alternatives, and remedial design for the Project. The frequency of TWG meetings is dependent on Project needs but in general between monthly to quarterly.

The TLP was created as a result of an understanding that a forum was needed to enable senior officials of Tribes and stakeholder groups to provide input to the regulatory agencies and PG&E on the direction of actions necessary to complete the Project. The purpose of the TLP is to exchange information, views, and opinions on various proposed actions to ensure timely development, selection, and implementation of the groundwater and soil remedy for the Site. The intent is to provide a senior-level perspective of each participant’s interest, and gain understanding of differing points of view that could be considered before critical decisions are made by the lead regulatory agencies. The TLP has met several times since 2008, prior to critical Project decisions.

A subgroup of the TLP is the CTF. The CTF was formed to develop tools and implement ideas to improve communications and enhance stakeholder understanding of the technical and regulatory processes of the Project. The goal is to foster timely and effective project management, and early collaboration with Tribal Nations and stakeholders, and to inform state and federal agencies on issues and concerns prior to decision making on the Project.

In addition to these meeting venues, DTSC and DOI continue to be actively engaged in consultation with Tribal Nations regarding the potential impacts of the project to the Tribes' Traditional Cultural Property (TCP) as determined and established by the Bureau of Land Management.