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• • <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> Winston H.Hickox Robert Schneider,Chair ' <br /> Gray Davis <br /> Secretaryfor Fresno Branch Office Governor <br /> Environmental Internet Address: http://www.swmb.ca.gov/—mgcb5 <br /> Protection 1685 E Street,Fresno,California 93706-2020 <br /> Phone(559)445-5116•FAX(559)445-5910 <br /> 28 February 2003 <br /> MAR 0 3 2003 <br /> ENPERM�MSERVICENT aLTH <br /> Ms. Penny T. Fottrell <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, SURLAND HOMES PROPERTY,TRACY,SAN JOAQUIN <br /> COUNTY <br /> ChevronTexaco has conducted a soil and groundwater investigation at the Surland Homes property in <br /> Tracy, San Joaquin County since 1998. The purpose of the investigations was to determine the lateral and <br /> 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 this area. In addition,present in the right-of-way was the former Associated Pipe Line (APL) <br /> Company's (predecessor to Texaco and now ChevronTexaco) pipeline that transmitted heavy crude from <br /> the Central Valley to the Bay Area from the early 1900s to the 1970s. <br /> The findings of the field investigations were evaluated by ChevronTexaco for assessing the potential <br /> human health risks associated with residual petroleum hydrocarbons in soil and groundwater at the site. <br /> The investigation reports and a Health Risk Screening Evaluation (HSE) were prepared by Geomatrix <br /> Consultants, Inc. for ChevronTexaco. Review of the information provided indicates that the vertical and <br /> lateral extent of impacted soil and groundwater has been delineated. <br /> The HSE report, dated 22 August 2002, indicates that four groundwater monitoring events were conducted <br /> for three site monitoring wells between September 1998 and October 1999. Monitoring well TW-2, <br /> located between two residences, was destroyed in 1999. Two final groundwater sampling events were <br /> completed for the two remaining wells (TW-1 and TW-3)in January and April 2000. <br /> During the first two sampling events, total petroleum hydrocarbons as diesel (TPH-d) was analyzed using <br /> a silica gel preparation procedure. However, during the remaining sampling events, TPH-d was analyzed <br /> both with and without the silica gel preparation procedure. During the final two quarterly sampling events <br /> in 1999, the maximum TPH-d concentration was detected at 120 µg/L and 150 µg/L, respectively in <br /> monitoring wells TW-1 and TW-3. Prior to well destruction, a petroleum hydrocarbon sheen was <br /> California Environmental Protection Agency <br /> 0 A <br /> 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 httpd/www.swrcb.ca.gov/mgcb5 <br />