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a.� <br /> California Regional Water Quality � pid <br /> Central Valley Region rT P'-t'T SERVICE <br /> Winston H.Hickox Robert Schneider,Chair m MAR 2n PN 12L5 � J <br /> Secretary for 2 Gray Davis <br /> Fresno Branch Office Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/—rwgcb5 <br /> Protection 1685 E Street,Fresno,California 93706-2020 <br /> Phone(559)445-5116•FAx(559)445-5910 <br /> 19 March 2003 / V <br /> Mr. Scott Mansholt <br /> ChevronTexaco <br /> Chevron Environmental Management Company <br /> P.O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW OF SOIL AND GROUNDWATER INVESTIGATIONS AND HEALTH RISK <br /> SCREENING EVALUATION, FORMER BURNS PROPERTY,TRACY, SAN JOAQUIN <br /> COUNTY <br /> ChevronTexaco has conducted a soil and groundwater investigation at the former Burns property.in Tracy, <br /> San Joaquin County from 1999 to 2001. The purpose of the investigations was to determine the lateral <br /> and vertical extent of impacts on soil and groundwater caused by petroleum hydrocarbon leaks from an <br /> abandoned crude oil pipeline (Old Valley Pipeline, OVP) in operation from the early 1900s to the late <br /> 1950s. In addition, present in the right-of-way was the former Associated Pipe Line (APL) Company's <br /> (predecessor to Texaco and now ChevronTexaco) pipeline that transmitted heavy crude from the Central <br /> Valley to the Bay Area from the early 1900s to the 1970s. Currently, a large retail shopping mall and <br /> accompanying asphaltic concrete parking lot covers the site. <br /> The investigation reports and a Health Risk Screening Evaluation (HSE) were prepared by Geomatrix <br /> Consultants, Inc. for ChevronTexaco. Regional Board review of the information indicates that the vertical <br /> and lateral extent of impacted soil and groundwater has been delineated. The findings of the field <br /> investigations were evaluated by ChevronTexaco for assessing the potential human health risks associated <br /> with residual petroleum hydrocarbons in soil and groundwater. <br /> According to the reports, the majority of residual petroleum hydrocarbons present in soil were found at <br /> depths between 5.5 and 14 feet below ground surface (bgs). Soils from the surface to 5-feet above the <br /> OVP were not affected. Total petroleum hydrocarbons as crude oil (TPH-c), TPH as gasoline (TPH-g), <br /> TPH as diesel (TPH-d), BTEX (benzene, toluene, ethylbenzene, and total xylenes), and select polynuclear <br /> aromatic hydrocarbons (PAHs) were detected in soil samples. <br /> Low concentrations of TPH-g, TPH-d, toluene, xylenes, and select PAHs were detected in groundwater <br /> samples obtained from within the area of affected soil. Depth to groundwater is approximately 11 to 13 <br /> feet bgs. During the most recent site investigation in October 2000, TPH-d was detected at 620 µg/L (the <br /> maximum concentration in groundwater reported for the site) in one groundwater sample. A groundwater <br /> sample obtained from a temporary well approximately 180-feet directly downgradient, reported 63µg/L, <br /> California Environmental Protection Agency <br /> 05 Recycled Paper <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways <br /> you can reduce demand and cut your energy costs,see our Web-site at http://www.swrcb.ca.gov/rwgcb5 <br />