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<br />. <br /> <br />. <br /> <br />Hexavalent chromium has been detected in various monitoring wells around the <br />gas compressor site. A Draft Cleanup and Abatement Order (CAO), requiring PG&E to <br />take necessary action to cleanup a hexavalent chromium groundwater plume migrating <br />towards the Colorado River from the PG&E's Topock Gas Compressor station, was <br />prepared by the California Regional Water Quality Control Board - Colorado River Basin <br />Region (CRWQCB), On August 8, 2003, after receiving assurance from the Department <br />of Toxic Substances Control (DTSC) that the DTSC will work with PG&E to expedite <br />cleanup action, the CR WQCB agreed to withdraw its Draft CAO and allowed the DTSC <br />to be the administrating lead agency for implementing the cleanup of the site, The <br />investigation was directed by DTSC to PG&E in accordance with the Resource <br />Conservation and Recovery Act (RCRA) corrective action process. <br /> <br />Messrs, Abbas Amir-Teymoori and Jay Chen of the Board staff attended the <br />Technical Committee meeting of the Consultative Work Group (CWG) for the PG&E <br />Topock Gas Compressor Station on February 26, 2004, and the CWG meeting on <br />February 27, 2004, at the MWD's office, During the meeting, PG&E's consultants, <br />CH2M & Hill and Ecology and Environment, Inc" presented its RCRA Facility <br />Investigation (RFI) report, focuing on the hydrogeological monitoring and sampling <br />results, An approximate limit of hexavalent Chromium groundwater plume at the <br />concentration of 0.05 mgll was delineated. In order to determine the boundary of <br />contamination, CWG concluded that the following further tasks needed to be completed: <br />I) more pumping tests and samplings at the well W20 cluster; 2) a set of thorough <br />background chemical investigation to determine the baseline and possible other <br />pollutants, such chlorinated solvents, other heavy metals, etc.; 3) possible locations of <br />additional extraction wells between wells W20 and W30 and/or monitoring well(s) north <br />to the facility; and 4) Pump and Treat the contaminated groundwater plume to create a <br />reverse hydraulic gradient to prevent the contaminated groundwater plume from moving <br />toward the Colorado River. Another alternative under study includes the construction of a <br />groundwater barrier to prevent movement of the contaminated water to the Colorado <br />River. <br /> <br />Included in the Board folder is a copy' of revised Waste Discharge Requirements <br />(WDR) to be issued by the CRWQCB to update the current WDR for the wastewater <br />treatment plant for the Topock Gas Compressor Station based on the emergency project <br />need. The hexavalent Chromium contamination was addressed by Ms. Lisa Anderson of <br />MWD in her letter to Mr. Watson Gin, Deputy Director of DTSC, for an immediate <br />remedial action, A copy of Los Angeles Times news concerning the threat of the <br />contamination groundwater plume moving toward the Colorado River and an Executive <br />Summary of the PG&E's consultant (Ecology and Environment. Inc,) RCRA Facility <br />Investigation report are also included in the handout materials for your reference, <br /> <br />Lower Basin Salinity Management Study <br /> <br />Reclamation's Lower Colorado Region is moving ahead with plans to initiate a <br />study of salinity-related issues within the Lower Basin. The study plans to evaluate the <br />benefits to the Lower Basin associated with implementation of the Title II efforts <br /> <br />10 <br />