In February 2007, PG&E submitted to the California Regional Water Quality Control Board, Lahontan Region, the document, “Groundwater Background Study Report.” The purpose for the background study was to estimate the concentration of naturally-occurring total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] in groundwater near the PG&E natural gas compressor station in Hinkley, California.

The background study was completed based on the September 2004 “Revised Background Chromium Study Work Plan.” The Work Plan incorporated comments from three University of California professors who peer-reviewed the original 2002 work plan. As a result of the peer review, the criteria for selecting wells for the study was refined, depth-discrete sampling was added, and the statistical analysis method used to evaluate the data was selected. The Work Plan was accepted by the Water Board in November 2004.

View the August 2008 Background Chromium Study.

Since April of 2013, the Lahontan Water Board and the Community Advisory Committee (CAC) have been working with Dr. John Izbicki, a Hydrologist with the U.S. Geological Survey (USGS), to learn more about the groundwater conditions in Hinkley. Izbicki, a leading expert in his field, has worked for the USGS for more than 25 years in Maryland, Massachusetts, and California. While in California, Izbicki’s studies have focused on understanding the physical hydrology of coastal and desert aquifer systems. The independent expertise offered by Izbicki will help the Water Board and the CAC better understand how ground water in the Hinkley Valley may impact PG&E’s remediation program.

In September of 2013, Dr. John Izbicki submitted a draft scope of work to study the occurance of natural and anthropegenic (man made) chromium 6 in the Hinkley area. The purpose of this study is to evaluate the occurrence of natural and anthropogenic chromium 6, and estimate background chromium 6 concentrations upgradient, near the plume margins, and downgradient from the mapped chromium 6 contamination plume. The study is expected to last 5 years. To view the draft scope of work document click here.