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California Regional Water Quality Control Board <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Alan C.Lloyd,Ph.D. Arnold <br /> Secretaryfor Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 Governor <br /> Protection (559)445-5116•Fax(559)445-5910 <br /> http://www.watabouds.ca.gov/cmtralvalley <br /> 30 March 2006 <br /> MAP, 3 1 2006 <br /> ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> San Ramon, California 94583-2324 <br /> REVIEW OF WORKPLAN,ADDITIONAL SUBSURFACE INVESTIGATION, LYOTH OFFSITE, <br /> TRACY, SAN JOAQUIN COUNTY <br /> Central Valley Regional Water Board staff has reviewed the referenced workplan, dated 23 March 2006, <br /> for the Chevron Old Valley Pipeline (OVP)project downgradient of the former Lyoth Loading Station <br /> property, which is located at 26501 Banta Road, in Tracy, San Joaquin County. The workplan was <br /> prepared for Chevron by Science Application International Corporation(SAIC). In addition, we <br /> reviewed other soil and groundwater investigation reports conducted since 1990 for the former Lyoth <br /> Loading Station property. <br /> Historically, several aboveground storage tanks were utilized for temporary containment of crude oil and <br /> Bunker C locomotive fuel at the loading station as part of the OVP system. The crude oil and Bunker C <br /> fuel were transferred from storage to railroad cars from the early 1900's until 1957 when the tanks and <br /> facility were dismantled and removed from the site. Hoffman Brothers Trucking Company purchased <br /> the property several years ago and has operated a trucking operation at the site since that time. <br /> The Lyoth Offsite property is directly north and downgradient of the former Lyoth crude oil loading <br /> station located at the intersection of Banta Road and the Southern Pacific Railroad. Currently, there are <br /> four groundwater monitoring wells on-site and two on the Lyoth Offsite property. Depth to groundwater <br /> ranges from approximately 15 to 19 feet and the gradient is north-northeast. <br /> Following review of recent semi-annual reports, Regional Board staff determined that the extent of <br /> impacted groundwater had not been delineated downgradient offsite -north of MW-1, MW-6, and <br /> MW-7. A subsequent off-site soil and groundwater investigation by SAIC in 2005 determined that <br /> elevated concentrations of crude oil reported as total petroleum hydrocarbons as diesel (TPHd) between <br /> 87 and 3,600 µg/1 was detected in groundwater samples from the three offsite investigative borings. <br /> Analysis for the 15 and 25-foot soil samples did not report TPH as crude oil (TPHc)present in the <br /> borings. Additionally, according to the boring lithologic logs, there was no evidence of petroleum <br /> hydrocarbons present in the shallower soils. <br /> California Environmental Protection Agency <br /> rro Recycled Paper <br />