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California Regional Water Quality Control Board �"��` <br /> Central Valley g � <br /> Region <br /> Robert Schneider,Chair r�d�,� <br /> Terry Tamminen Fresno Office Arnold Schwarzenegger <br /> Secretary.for 1685 E Street,Fresno,California 93706-2020 Governor <br /> Environmental Phone(559)445-5116•FAX(559)445-5910 <br /> Protection Internet Address: http://www.swrcb.ca.gov/--rwgcb5 <br /> MD <br /> 4 December 2003 UE C 0 8 2003 <br /> ENVIRONMEN 1 HEALTH <br /> PERMIT/SERVICES <br /> Mr. M. Scott Mansholt <br /> ChevronTexaco <br /> Chevron Environmental Management Company <br /> P.O. Box 6012 <br /> San Ramon, California 94583-2324 <br /> OFFSITE SOIL AND GROUNDWATER INVESTIGATION, U. S. CAN/WELTY ROAD, <br /> VERNALIS, SAN JOAQUIN COUNTY <br /> We have reviewed the 14 November 2003 Offsite Soil and Groundwater Investigation, US Can/Welty Road <br /> site, 35275 Welty Road, Vernalis, San Joaquin County, submitted by your consultant, Geomatrix <br /> Consultants, Inc. (Geomatrix). Additionally, we reviewed previous soil and groundwater investigation <br /> reports conducted by Geomatrix and others from 1995 to 2002. The purpose of the investigations was to <br /> determine the lateral and vertical extent of impacts to soil and groundwater caused by petroleum <br /> hydrocarbon leaks from abandoned crude oil pipelines (Old Valley Pipeline, OVP). <br /> The OVP was formerly operated by predecessors of Chevron and Texaco (now ChevronTexaco), from the <br /> early 1900s to the 1970s. The former OVP, present between the northeastern property boundary and <br /> Highway 33, transmitted heavy crude oil from Kern County to the Bay Area. A Kinder Morgan Energy <br /> Partners, L. P., petroleum product pipeline that reportedly transports gasoline,jet fuel, and diesel is located <br /> between the site and State Highway 33. <br /> According to the reports, residual petroleum hydrocarbons were found in soil within two areas along the <br /> northeastern site boundary as follows: 1) adjacent to the northeast corner of an existing building, and, 2) <br /> further west in an area used for parking. The vertical extent of total petroleum hydrocarbons as diesel <br /> (TPH-d) in groundwater on-site is estimated to be similar to the vertical extent of affected soil (between <br /> 55 and 89 feet in GMX-8) within the northeastern areas of affected soil. <br /> Historically, and during the current investigation, a petroleum sheen has been observed in two on-site <br /> monitoring wells, low concentrations of petroleum hydrocarbons were present in a third well, and TPH <br /> compounds were not detected in the fourth (upgradient) on-site monitoring well. Depth to groundwater <br /> at the site is approximately 30 to 35-feet and the gradient is generally northeast. <br /> California Environmental Protection Agency <br /> (d Recycled Paper <br />