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California Regional Water Quality Control Board <br /> s Central Valley Region <br /> � k P <br /> Karl E. Longley,SCD,P.E.,Chair <br /> Arnold <br /> Linda S.Adams ary for 1685 E Street,Fresno,California 93706 Schwarzenegger <br /> Secretaryf (559)445-5116•Fax(559)445-5910 Governor <br /> P,nviroor <br /> Protection http://www.waterboards.ca.gov/centralvalley (�r�";;::`MVV_­___ <br /> ��n /;_I�;__ <br /> 27 March 2009 HIM 20 U <br /> MAR 3 0 2009 <br /> ENVIRONMENT HEALTH <br /> M. Scott Mansholt PERMIT/SERVICES <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> Room 3432 <br /> San Ramon, CA 94583 <br /> REVIEW - SOIL AND GROUNDWATER INVESTIGATION REPORT, BANTA ROAD — UNION <br /> PACIFIC RAILROAD SITE, TRACY, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted a Soil and Groundwater <br /> Investigation Report (Report) dated 13 February 2009, for Banta Road — Union Pacific <br /> Railroad (UPRR) site (Site). The Site, at the intersection of South Banta Road and the UPRR <br /> tracks, is in southeast Tracy. The Report was prepared for Chevron by Science Applications <br /> International Corporation (SAIC). <br /> Background <br /> During December 2003 to February 2004, South San Joaquin Irrigation District installed a <br /> 30-inch diameter water main along the east side of South Banta Road. A bore-and-jack <br /> process was used to place the water main beneath the UPRR tracks. During the process, <br /> petroleum hydrocarbon affected soil was encountered from approximately 11 feet below <br /> ground surface (bgs) to 19 feet bgs. Additional investigation and analytical results of soil <br /> samples reported total extractable petroleum hydrocarbons at concentrations of 2,400 <br /> milligrams per kilogram (mg/kg) at 12 feet bgs to 190 mg/kg at 19 feet bgs. The extent of <br /> affected soil was not determined and further delineation was needed. <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br /> approved a workplan for additional soil and groundwater investigation in a letter to Chevron <br /> dated 18 April 2006. The purpose of the investigation was to evaluate the lateral extent of <br /> affected soil identified previously and determine if groundwater was affected. <br /> Current Investigation <br /> During November 2008, SAIC advanced three borings to depths of 28 to 32 feet bgs and <br /> obtained soil samples for analysis of total petroleum hydrocarbons as crude oil (TPHc); <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX); and polynuclear aromatic hydrocarbons <br /> (PAHs). Groundwater samples were analyzed for TPH as diesel (TPHd), BTEX, PAHs, <br /> General Minerals, and total dissolved solids (TDS). <br /> According to the investigation, TPHc was detected at depths of 5 to 18 feet bgs at <br /> concentrations from 4.8 to 5.3 mg/kg to non-detect (ND); samples from 20 feet were ND. <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />