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Californ4pegional Water Quality C4prol Board <br /> Central Valley Region r' <br /> Karl E. Longley,ScD,PE,Chair <br /> Arnold <br /> Linda S.Adams Fresno Branch Office Schwaraenegger <br /> Secretaryfor 1685 E Street,Fresno,California 93706 Governor <br /> Environmental (559)445-5116•Fax(559)445-5910 <br /> Protection http://www.waterboards.ca.gov/centralvalley <br /> 12 June 2007 <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road, Rm K2066 <br /> San Ramon, CA 94583-2324 Z(osp I � � <br /> REVIEW OF SOIL AND GROUNDWATER INVESTIGATION, LYOTH OFFSITE PROPERTY, <br /> TRACY, SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced report for the Old Valley Pipeline <br /> (OVP) and Tidewater Associated Oil Company (TAOC; both are Chevron predecessors) Lyoth <br /> Offsite project located at 26501 Banta Road, in Tracy, San Joaquin County. The report dated <br /> 7 May 2007, was prepared for Chevron by Science Applications International Corporation <br /> (SAIC). <br /> Lyoth Offsite is directly north and downgradient of the former Lyoth crude oil loading station <br /> located north and east of the intersection of Banta Road, the California Northern Railroad, and <br /> Union Pacific Railroad (UPRR) lines. Currently, there are four groundwater monitoring wells <br /> on-site and two on the Lyoth Offsite property. Depth to groundwater ranges from <br /> approximately 15 to 19 feet and the gradient is north-northeast. <br /> Regional Water Board staff approved a workplan 30 March 2006 to conduct an investigation to <br /> evaluate the extent of petroleum affected groundwater on the Lyoth Offsite project. According <br /> to previous investigations, the extent of affected soil has been delineated onsite, but affected <br /> groundwater has not been adequately defined offsite to the north and downgradient of the <br /> Lyoth loading station. <br /> The purpose of the current investigation was to advance borings and collect groundwater <br /> samples for analysis to delineate the extent of groundwater impacts north of the former Lyoth <br /> loading station. In January 2007, SAIC advanced three borings and collected soil and <br /> groundwater samples for analysis of the site constituents of concern; groundwater samples <br /> were submitted for fuel fingerprint analysis. The additional borings (B-4, 5, and 6) were <br /> advanced further downgradient of three 2005 sampling locations (B-1, 2, and 3) which had <br /> reported total petroleum hydrocarbons as diesel (TPHd) concentrations to 3,600 micrograms <br /> per liter (ug/1). <br /> SAIC's report compared the soil and groundwater results to the U.S. Environmental Protection <br /> (U.S. EPA) Region 9 Preliminary Remediation Goals (PRGs) and San Francisco Bay Regional <br /> California Environmental Protection Agency <br /> ca Recycled Paper <br />