I CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD LAHONTAN REGION CLEANUP AND ABATEMENT ORDER No. 6-87-160 Requiring the Pacific Gas and Electric Company to Cleanup and Abate the Effects of Past waste Discharges of Hexavalent Chromium to Groundwaters of the Mojave Hydrologic Unit. The California Regional water Quality Control Board, Lahontan Region finds: 1. Pacific Gas and Electric Company, which owns and operates the Hinkley Compressor Station located southeast of the town of Hinkley in San Bernardino County, is in the of Section 2, T9N, R3w M. The facility is located in the Harper Valley Subarea of the Mojave Hydrologic Unit. For the purposes of this order, Pacific Gas and Electric is hereinafter referred to as the "discharger". The discharger's Hinkley facility is a natural gas compressor station operating on a pipeline running from Texas to San Francisco, California. The facility is currently operating under Board Order No. 6-82-79. The Regional Board originally established waste discharge requirements for the industrial wastewater ponds in 1974 under Board Order No. 6~74-64. On December 7, 1987 the discharger notified the Regional Board and the San Bernardino County Department of Environmental Health Services of the discovery of 0.58 of hexavalent chromium in an "9onsite groundwater monitoring well north of the facility's industrial wastewater ponds. The contamination was discovered on November 30, 1987 as part of an ongoing environmental assessment program at Pacific Gas and Electric facilities. Representatives of the discharger have indicated that the industrial wastewater ponds are the likely source of the chromium in the groundwater because a chromium-based corrosion inhibitor used in their cooling tower blowdown water was discharged to unlined industrial wastewater ponds between 1951 and 1966. During this time the unlined ponds received approximately 750,000 gallons/month of blowdown wastewater from the evaporative coolers. Since the discovery of the chromium contamination, the discharger has hired the consulting engineering firm of Harding Lawson and Associates to conduct a preliminary site investigation. During the week of December 7, 1987 over fifty municipal, domestic, and agricultural water wells in the area were sampled. Of these, eleven wells proved to have chromium concentrations greater than the drinking water standard of 0.05 ppm. From this same sampling program it has been determined that the plume of chromium contamination extends approximately one mile north of the facility. Pacific Gas Electric Cleanup and Abatement Order No. 6-87-160 6. Sediments underlying the area are several hundred feet thick and are composed of lenticular sand and gravel bodies separated by thin clays and silts. The groundwater aquifer is thought to be unconfined and groundwater flow is from south to north. Depth to groundwater is typically eighty feet. The closest water wells downgradient from the wastewater ponds are at a dairy approximately one thousand feet north of the facility. Groundwater quality for the aquifer is excellent for most beneficial uses with total dissolved solids in the range of 200 to 400 ppm. 7. The Regional Board adopted a water Quality Control Plan for the South Lahontan Basin on May 8, 1975. 8. The beneficial uses of the groundwaters of the Harper Valley Subarea of the Mojave Hydrologic Unit as set forth and defined in the Water Quality Control Plan for the South Lahontan Basin are: municipal and domestic supply agricultural supply industrial service freshwater replenishment Q0 UN 9. The discharge of hexavalent chromium has caused a pollution of the groundwater underlying the site and has polluted groundwater downgradient of the site. 10. Section 13304 of the California water Code states in part that: "Any has caused or waste to be discharged or deposited where it is, or probably will be, discharged into the waters of the state and creates, or threatens to create, a condition of pollution or nuisance, shall upon order of the Regional Board clean up such waste or abate the effect thereof or, in the case of threatened pollution or nuisance, take other necessary remedial action." 11. This enforcement action is being taken to enforce provisions of the California Water Code and as such is exempt from the provisions of the California Environmental Quality Act (Public Resources Code, Section 21000 et seq.) in accordance with Section 15321, Chapter 3, Title 14, California Administrative Code. IT IS HEREBY ORDERED that pursuant to the California water Code Section 13304, that Pacific Gas Electric Company shall: 1. By January 31, 1988 have an engineering firm under contract capable of performing a site investigation/characterization of the chromium contamination at the Hinkley site. at Pacific Gas Electric Cleanup and Abatement Order No. 6-87-160 2. Submit to the Regional Board by Februar 28 1988 a site investigation/site characterization workplan for approval. 3. Begin the site investigation/characterization by March 15, 1988. 4. Submit to the Regional a status report on the site investigation by June 15, 1988. 5. Complete the field work for the site investigation by September l5, 1988. 6. Submit the results of the site investigation and a recommended remedial action plan to the Regional Board by October 15, 1988. 7. within ninety days of approval of the remedial action plan initiate cleanup of the site. Failure to comply with the terms or conditions of this order may result in this matter being referred to the Attorney General of the State of California for such legal action as he may deem appropriate. A ORDERED 6 DATED: /07 *2 7'63 7 O.R. BUTTER IELD EXECUTIVE OFFICER