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INTERIM SOIL AND GROUNDWATER <br /> CORRECTIVE ACTION SUMMARY REPORT <br /> 8940 W Walnut Grove Road, Thornton, CA <br /> 3.3 Additional Soil Boring Investigation <br /> In July 1999, five direct push soil borings were advanced along the perimeter of the UST <br /> excavation to investigate the vertical and lateral extent of soil and groundwater contamination, <br /> and four hand augured soil borings were advanced to investigate the lateral extent of shallow soil <br /> contamination <br /> Total petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel <br /> (TPHd) were detected in the soil at low to moderate levels, but only boring SB3 had detectable <br /> levels of benzene and methyl tert butyl ether (MTBE) Elevated levels of benzene, toluene, <br /> ethylbenzene xylenes (BTEX), TPHg, TPHd, and MTBE were detected in grab groundwater <br /> samples collected during drilling The data suggested that the vertical extent of soil contamination <br /> did not exceed 15 feet below ground surface (bgs) and occurred within a relatively limited area in <br /> • the vicinity of the former USTs Analytical results are summarized in Table 3 Boring Iocations <br /> Eare depicted on Figure 4 <br /> Based on the results of the investigations, source removal excavation and supplemental <br /> groundwater removal and disposal were proposed in the Interim Corrective Action Workplan <br /> Idated February 15, 2000 <br /> 4.0 INTERIM CORRECTIVE ACTION <br /> 4.1 Resources <br /> Sean Garvey, a Ground Zero geologist, and John Lane, a California Registered Geologist, <br /> supervised excavation and sample collection activities Mr Harlin Knoll of PHS/EHD observed <br /> field activities and conducted the site inspection Excavation was conducted by Oil Equipment <br /> Service Argon Laboratory (Argon), a State-certified analytical laboratory, conducted the <br /> analysis, and Denbeste Transportation transported groundwater to Sacramento County Regional <br /> Wastewater facility for disposal <br /> G1Data1GROUNDZEIMAN5ER1Repom\soilexsum doc 3 <br />