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` California Regional Water Quality Control Board '- <br /> 14�0;\ Central Valley Region <br /> o � <br /> Robert Schneider,Chair �,°:_"�. <br /> Linda S.Adams Arnold <br /> Secretaryfor Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 <br /> - ax( Governor <br /> Protection (559)4455116•Fax 559�445-5910 <br /> http://www.waterboards.ca.gov/centralvalley <br /> 16 November 2006 <br /> NOV 1 7 2006 <br /> M. Scott Mansholt EN�R�ITtSERVICES HEALTH <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road, Rm K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW OF SOIL AND GROUNDWATER INVESTIGATION, iPAT LLUS PROPERTY, <br /> TRACY, SAN JOAQUIN COUNTY ( l q 8aY <br /> Regional Water Board staff has reviewed the referenced report, dated 28 September 2006 <br /> prepared for Chevron by Science Applications International Corporation (SAIC). The project <br /> site is located along the former Old Valley Pipeline (OVP) and Tidewater Associated Oil <br /> Company (TAOC) right-of-way adjacent to W. Byron Road and the Union Pacific Railroad, <br /> immediately northwest of Tracy (see attached Figure provided by SAIC). Detailed review <br /> comments are provided in the attached memorandum and summarized below. <br /> Elevated total petroleum hydrocarbons as crude oil (TPHc) in soil were identified by borings at <br /> three different areas, the lateral extent was delineated at one location and partially delineated <br /> at the other two locations. The vertical extent of affected soil is between 20 and 25.5-feet. <br /> TPH as diesel (TPHd) was ND for 16 groundwater samples. Seven groundwater samples <br /> reported TPHd from less than 100 micrograms per liter (ug/1) to 6,300 ug/l. Benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) was ND in all samples. PAH (polynuclear aromatic <br /> hydrocarbon) concentrations in a majority of the samples were generally less than regulatory <br /> environmental screening levels. Certain PAH concentrations that exceeded screening levels <br /> were detected in borings having elevated TPH concentrations it soil and groundwater. Depth <br /> to groundwater ranged from approximately five to eleven feet. <br /> Total dissolved solids water quality values are consistent with concentrations documented at <br /> nearby Mountain House and the City of Tracy OVP projects. Review of Department of Water <br /> Resources records indicates there are three nearby domestic wells that could be affected by <br /> OVP and/or TAOC leaks. <br /> Based on our review, we have the following comments: <br /> • Affected groundwater has not been adequately defined for the majority of the site. <br /> Additional borings are needed to evaluate the extent of affected groundwater <br /> upgradient and downgradient of the site, <br /> California Environmental Protection Agency <br /> Cpl Recycled Paper <br />