Occurrence of natural and anthropogenic hexavalent chromium (Cr VI) in groundwater near a mapped plume, Hinkley, CA


The U.S. Geological Survey developed the scope of this study in collaboration with the Technical Working Group (TWG) composed of local stakeholders (the Hinkley Community Advisory Committee, CAC), community advisors (Project Navigator, Inc.), State regulatory agencies (Lahontan Regional Water Quality Control Board, LRWQCB), and Pacific Gas and Electric (PG&E) and their consultants. TWG meetings beginning in January 2013 familiarized members with available data; and with issues of local, regulatory, and technical concern within the study area.

The scope of this study includes the following tasks:

  1. evaluation of existing data;
  2. sample collection and analyses of rock and alluvium;
  3. sample collection and analysis for water chemistry and multiple tracers,
  4. evaluation of geologic, hydrologic, and geochemical conditions in western, northern, and eastern subareas within the study area;
  5. evaluation of historic and present-day groundwater movement,
  6. evaluation of the occurrence of natural and anthropogenic chromium;
  7. determination of background Cr VI concentrations; and
  8. assessment of the fate of chromium following in-situ reduction.

Procedures for evaluation of laboratories, quality assurance, and data management are discussed in this section following discussion of the study tasks. Reports to be prepared for this study are discussed in a separate reports section. A summary of the project tasks and the primary question each task is intended to answer is provided in Table 1.

Work plans and implementation of each of these tasks (including identification of specific wells to be sampled as part of this study) will be developed in collaboration with the TWG as the study moves forward. To assist with study design, in April 2013, PG&E and their consultants in collaboration with the TWG evaluated existing water-chemistry data, and collected a “snapshot” of selected proposed tracers. These data, in combination with other existing data, are discussed within this proposal.

Tasks and questions addressed by the study

Tasks and questions addressed by the study

Cooperating Agency: Lahontan Regional Water Quality Control Board
Project Chief: John A. Izbicki
Phone: 619-225-6131
Email: jaizbick@usgs.gov

California Water Conditions

Real-Time California Streamflow Conditions