USGS issues Hinkley Chromium-6 Background Study

On April 25, 2023 the United State Geological Survey (USGS) issued the long awaited Hinkley Cr(VI) Background Study (Study) to the public. The completion of the Study is a major milestone for PG&E’s Cr(VI) Groundwater Remediation Program.
The USGS lead scientist in charge of the effort was Dr. John Izbicki and well respected in the Hinkley Community. Dr. Izbicki is a renowned expert in the fields of geology and hydrogeology of the Mojave Desert. The purpose of the Study was to identified natural occurring and man-made Cr(VI) in the Hinkley Valley. The process to complete the Study took ten years to complete and involved a comprehensive Scope of Work that involved stakeholders’ input. A Technical Work Group (TWG) was created to ensure the technical integrity and transparency of the Study. The TWG consisted of the USGS, Lahontan Regional Water Quality Control Board (Water Board) Staff, IRP Manager (PNL), PG&E, and Hinkley Community Members. Dr. Izbicki presented an overview of his results in front of the Water Board during the Board’s Annual Meeting on April 26 at Barstow Community College in Barstow California. Dr. Izbicki presented an extent of the man-made plume based on a Summative Scale Analysis approach that was agreed upon with the TWG. The new Cr(VI) background concentration Dr. Izbicki presented is 2.8 part per billion (ppb), previous concentration was 3.1 ppb. Dr. Izbicki presentation can be viewed on the link below:

The next phase of the PG&E Cr(VI) Groundwater Remediation Program will be to incorporate the results of the Study into an updated Cleanup and Abatement Order (CAO) from the Water Board. The result of the Study will determine the final remedial target, monitoring and sampling program.