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California Regional Water Quality Control Board <br /> Central Valley Region <br /> M � <br /> Robert Schneider,Chair <br /> Terry Tamminen Arnold Schwarzenegger <br /> Secretary for Sacramento Main Office Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/rwgcb5 <br /> Protection 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114 <br /> Phone(916)4643291 <br /> 21 June 2004 V D <br /> Mr. Sheldon Heckman, c/o Kama E.Herrigfeld JUN 2 4 2004 <br /> Herum Crabtree Brown <br /> 2291 W.March Lane, Ste.B-100 ENVIRONMENT HEALTH <br /> Stockton, CA 95207 PERMIT/SERVICES <br /> DOCUMENT REVIEWS, RIVER CITY PETROLEUMIFORMER CONNELL MOTOR LIFT TRUCK, 2211 <br /> NORTH WILSON WAY,STOCKTON,SANJOAQUIN COUNTY <br /> I reviewed the Quarterly Report—First Quarter 2004(Report)and Monitoring Well Installation Work Plan <br /> (Workplan),both dated 4 June 2004,prepared on your behalf by your consultant Advanced GeoEnvironmental, <br /> Inc. (AGE). The Report states that groundwater contamination associated with the Stoddard Spill area has been <br /> characterized for lateral and vertical extent, and is limited to the shallow groundwater zone. Gasoline(including <br /> 1,2-dichloroethane or 1,2-DCA)associated with the former USTs and dispensers release has moved through soil <br /> and groundwater into the deep groundwater zone at least 225 feet below ground surface(bgs) in the USTs area. <br /> The USTs release then continues under the site as a deeper dissolved plume beneath the Stoddard Spill area. The <br /> Report states that vertical and lateral extent of the USTs release has not been fully characterized by the existing <br /> groundwater monitoring well network and Cone Penetrometer Testing(CPT) groundwater investigations,and <br /> recommends installation of additional monitoring wells. An Interim Soil Vapor Extraction remediation system, <br /> installed in April 2004,is scheduled for startup in July 2004. <br /> Workplan: <br /> The Workplan proposes to continue characterization of the vertical extent of the petroleum hydrocarbon and 1,2- <br /> DCA groundwater plume in the UST area near the south fuel dispensers,with a two-phased installation of up to <br /> four single-completion groundwater monitoring wells (wells);-and additional phased installations of deep <br /> monitoring wells north, south, and inside the building for lateral extent. The initial Phase One wells would be <br /> screened at: <br /> • 200-205 feet bgs,and <br /> • 250-255 feet bgs. <br /> I concur to the proposal to target these two zones in Phase One of the Workplan. <br /> The Workplan states that 255 feet bgs may not be the complete vertical extent of contamination. The Report <br /> substantiates this claim with recent(March 2004) CPT grab groundwater sampling and analysis results,which <br /> detected petroleum hydrocarbon contamination, including 1,2-DCA,throughout the water column from 60 feet <br /> bgs down to 225 feet bgs in the source area. If the two Phase One wells are impacted,then the Workplan <br /> recommends a Phase Two installation of additional wells screened at: <br /> • 145-150 feet bgs, and <br /> • "If drilling depth and well design exceed the total of 250 feet, an additional scope will be transmitted to <br /> CVRWQCB-CVR Staff for concurrence and approval." <br /> California Environmental Protection Agency <br /> 0a Recycled Paper <br />