In February 1996, Pacific Gas and Electric Company (PG&E) entered into a voluntary agreement with the California Department of Toxic Substances Control (DTSC) to further investigate the nature and extent of contamination resulting from Station operations and to clean up related contamination. This agreement, the Corrective Action Consent Agreement (CACA), proscribes that PG&E follow an investigation and cleanup process governed by a federal law known as the Resource Conservation and Recovery Act (RCRA). PG&E agreed to conduct a RCRA Facility Investigation (RFI) to determine the extent of contamination and potential impacts to human health and the environment, and to gather information to support the evaluation and selection of a remedy to address the contamination.

In July 2005, PG&E entered into a voluntary Administrative Consent Agreement with the United States Department of the Interior (DOI). This Consent Agreement ensures compliance with federal requirements as set forth in CERCLA.

RFI/RI data collection activities started in 1996. The Groundwater Monitoring Program and other field investigations have contributed to the RFI/RI body of data. To view the most recent plume maps, based on quarterly groundwater data, please see the links below.

Three initial versions of the RFI/RI report have been developed and submitted to DTSC prior to the current versions. The first draft report was submitted in April 2000 and the second in February 2004. The third draft, submitted February 2005, was a comprehensive document that summarized all of the RFI data collected from 1996 through June 2004.

Because some of the property affected by operations at the Station is owned by the U.S. Department of the Interior (DOI), DOI is overseeing remedial actions pursuant to the Comprehensive Environmental, Response, Compensation, and Liability Act (CERCLA). Therefore, the 2005 Draft RFI/RI report and the subsequent Final RFI/RI report have been prepared to satisfy both RCRA (as managed by DTSC) and CERCLA requirements.

The Final RFI/RI report is divided into three volumes:

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

The Revised Final Volume 1 Report, Site Background and History, was approved by DTSC and DOI in August 2007. An addendum to the Volume 1 Report is anticipated to be prepared in a near future.

The Final Volume 2 Report, Hydrogeological Characterization and Results of Groundwater and Surface Water Investigation, was approved by DTSC and DOI in February 2009. Volume 2 addressed potential groundwater impacts associated with the past discharge of wastewater from the Station to Bat Cave Wash (designated as SMWU 1/AOC 1) and injection well PGE 8 (designated as SWMU 2). Pore water and river sediment characterization was also included. The Volume 2 Addendum, which was submitted to agencies, Tribal governments, and stakeholders in December 2008, includes supplemental data and information collected after the data cutoff period for Volume 2 (i.e., from October 2007 through September 2008). The Volume 2 Addendum was approved in June 2009.

The Volume 3 Report will include final characterization data to complete the RFI/RI requirements for the Site. Volume 3 will address the remaining SWMUs and AOCs identified in Volume 1 that are not covered in Volume 2. Volume 3 is expected to be completed and approved in late 2011.

Each approved RFI/RI Volume (and its addendum) will be released to the public and posted in the Information Repositories.

DTSC and DOI oversee the RFI/RI activities, and have directed PG&E to conduct a Groundwater Risk Assessment to provide information about potential health threats and ecological risks posed by affected groundwater and to assist risk management decision making. The Final Groundwater Risk Assessment is currently under preparation, and is anticipated to be complete in late 2009.