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California Regional Water Quality Control Board <br /> \� Central Valley Region !� ' <br /> Katherine Hart, Chair ��� <br /> Linda S.Adams 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Arnold <br /> Secretary for Phone(916)464-3291 -FAX(916)464-4645 Schwarienegger <br /> Environmental <br /> hitp//wAw�.walerboards.ca.gov/centralvaltey Governor <br /> Protection <br /> 16 March 2010 <br /> Mr. Robert Gray <br /> Pacific Gas and Electric Company <br /> Environmental Remediation <br /> 3401 Crow Canyon Road Room 176G <br /> San Ramon CA, 94583 <br /> SITE SAMPLING AND SOIL REMOVAL WORK PLAN, PACIFIC GAS AND ELECTRIC <br /> COMPANY, MCDONALD ISLAND COMPRESSOR STATION, ZUCKERMAN ROAD, <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> Regional Water Quality Control Board, Central Valley Region (Central Valley Water Board) <br /> staff reviewed the Site Sampling and Soil Removal Work Plan (Work Plan), dated <br /> 19 February 2010, for the McDonald Island site, located in San Joaquin County (Site). The <br /> Work Plan was prepared on your behalf by Arcadis. <br /> Arcadis proposes to determine the lateral and vertical extent of gasoline, diesel and motor oil <br /> range hydrocarbons, benzene, toluene, ethylbenzene and xylenes (BTEX) in soil at the Site. <br /> Analysis of soil samples collected during excavation of visually stained soil indicate diesel in <br /> concentrations up to 2,600 mg/kg as the primary impact to soil at the Site. Gasoline (up to <br /> 19 mg/kg), benzene (up to 0.0061 mg/kg), ethylbenzene and total xylenes (up to 0.020 rng/kg) <br /> are also present. <br /> Arcadis proposes to collect soil samples at 2, 4, 6 and 8 feet below ground surface in twelve <br /> primary locations and six step-out locations, if necessary, around the existing excavation. Grab <br /> groundwater samples will be collected from three of the borings. Soil and groundwater <br /> samples are proposed to be analyzed for gasoline, diesel, motor oil and BTEX. Arcadis <br /> proposes to use Regional Water Quality Control Board, San Francisco Region, Environmental <br /> Screening Levels (ESLs) as a screening tool to evaluate impacts to soil and groundwater at <br /> the Site. <br /> I concur with the Work Plan as proposed, but have the following comments: <br /> 1. Please include analysis for naphthalene at 2, 4, 6, and 8 feet bgs from at least one of the <br /> proposed twelve soil borings, and include naphthalene in the analysis of the grab <br /> groundwater sample. <br /> 2. As we have previously discussed, silica gel cleanup is not an approved method for analysis <br /> of hydrocarbons, unless supplemental analysis of background organic content indicates <br /> the hydrocarbons are naturally occurring. <br /> California Environmental Protection Agency <br /> zZ1DaRecycled Paper <br />