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California0gional Water Quality Con* Board <br /> Central Valley Region l ! <br /> Karl E.Longley,ScD,P.E.,Chair <br /> Linda S.Adams Arnold <br /> Secremryfor Sacramento Main Office <br /> 11020 Sun Center Drive 9200,Rancho Cordova,Cal ifomia 95670-6114 Schwarzenegger <br /> Environmental Phone 916 464-3291 •FAX 916 464-4645 Governor <br /> Protection � ) � ) <br /> htip://www.waterboards.ca.gov/centrals - <br /> 15 July 2008 JUL 7 2008 <br /> ENVIRONMEN-1 HEAUM <br /> PERK"i7/C�R\rirF <br /> Mr. Jeff Whitworth <br /> Shell Oil Products US <br /> 20945 S. Wilmington Avenue <br /> Carson, CA 90810 <br /> REVIEW OF INVESTIGATION WORK PLAN, FORMER SHELL CENTRAL VALLEY CRUDE <br /> OIL PIPELINES, HANSEN ROAD NEAR SCHULTE ROAD, TRACY, SAN JOAQUIN <br /> COUNTY <br /> Staff of the California Regional Water Quality Control Board, Central Valley Region (Regional <br /> Water Board) has reviewed the 6 June 2008 Investigation Work Plan, Former Shell Central <br /> Valley Crude Oil Pipelines, Cordes Ranch, Tracy (Work Plan) submitted by Science <br /> Application International Corporation (SAIC) on behalf of Shell Oil Products US (Shell). The <br /> Work Plan proposes additional investigative activities to further define the extent of <br /> groundwater contamination in the vicinity of boring B-75. In addition, the report presents the <br /> results of a records search of well completion reports with the California Department of Water <br /> Resources (DWR). <br /> Shell proposes to collect groundwater samples from two boring locations approximately 80 <br /> and 160 feet northeast of boring B-75 in the inferred down gradient direction. The borings will <br /> be advanced using a cone penetrometer testing (CPT) rig to determine the subsurface <br /> lithology and to collect groundwater samples. Groundwater samples will be collected at 20- <br /> foot depth intervals between first encountered groundwater and a depth of 150 feet below <br /> ground surface using discrete depth sampling equipment advanced by the CPT rig. Total <br /> Petroleum Hydrocarbons in the diesel (TPHd) and crude oil (TPHc) ranges will be analyzed <br /> using EPA Method 8015. Benzene, toluene, ethylbenzene, and xylenes (BTEX) will be <br /> analyzed using EPA Method 8260B. <br /> In response to the Regional Water Boards request for a sensitive receptor survey, Shell <br /> conducted a records search of DWR well completion reports to identify water supply wells <br /> located within a one mile radius of the site. A total of 201 water supply wells were identified <br /> within the search radius, most of which were located north of Interstate 205 near Von Sosten <br /> Road and Hansen Road. Three of the identified water supply wells were located within 2,000 <br /> feet of the site. Shell proposes conducting a field survey to locate and identify any additional <br /> water supply wells that may not have been identified in the DWR search. Shell will attempt to <br /> determine the depth of each well identified as well as the depth of the annular seal. <br /> California Environmental Protection Agency <br /> pia Recycled Paper <br />