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114 <br /> LATHROP PROPERT Y <br /> WKA No. 1184.02 <br /> ' January 30, 1992 <br /> Page 8 <br /> rM <br /> � i <br /> covered with construction grade polyethylene at a location on the property near its west- <br /> central boundary. Excavated contaminated soils totaled 360 cublc yards; the soils were <br /> i a stockpiled such that individual six-cubic-yard dumptrurk loads could be identlfled,providing <br /> the opportunity toaccurately.determine the voiurne of contaminated soils. <br /> �i <br /> The resulting excavation encompassed a lateral area of approximately 4700 square feet and <br /> ranged In depth from 10 to 12 feet below original sits grade. Seven excavation samples were <br /> f1 obtained subsequent to contaminated soils removal; the.samples were collected January 14, <br /> 1991. Three samples were obtained utilizing hand sampling.equipment from the bottom of <br /> the excavation (Samples E1 through E3) and one sample was obtained from each of the four <br /> excavation sidewails (Samples E4 through L7). The excavation samples were analyzed for <br /> total petroleum hydrocarbons (TPH, EPA method 8015 modified), benzene, toluene, xylene <br /> and ethyl benzene (BTX&E, EPA method 8020) and total lead (EPA method 7420). Plate 2 <br /> shows excavation sampling locations and Table.1 summarizes:soil,analytical results for <br /> excavation samples. <br /> t , Review of the analytical test results reveals non-detectable concentrations of BTX&E and TPH <br /> as diesel in all but one of the excavation soil samples;sample.E4.1 0'contained 0.00031 ppm,: <br /> toluene only The three bottom samples contained slight concentrations of TPH as gasoline <br /> 1: and #hs easterly,.sidewall sample -contairiod .17. <br /> ppm TPHas, gasoline;:fife atljer 'three. <br /> excavation samplescontained' TPH as gasoline concentrations. Five of the <br /> seven excavation samples contained non-detectable lead concentrations while two bottom <br /> samples, E 1 and E3,contained slight concentrations of lead. Complete laboratory test results f <br /> for excavation samples are contained in,Append1x A. <br /> The excavation was backfilled with the '.clean overburden soils subsequent;.to:verbal;:.' <br /> permission-from,Ms:Ratliff to do so.` <br /> a <br /> Soils Remediation <br /> Fifteen samples of the excavated, stockpiled soils were colle:.ted and analyzed for TPH and <br /> 8 <br /> TX&E; this corresponds to the San Joaquin County-required sampling rate of one discreet" <br /> sample per 25 cubic yards of material. The stockpiie.samples;which we identified as the Stk <br /> ser fes;contained an average concentration of TPH asgasoline of-1850 <br /> 4. g 9 ppm anti Tf'H as paint <br /> 1 3 thiimer of 1770 ppm. We determined that these contaminants could be remediated by <br /> ka <br /> WALLACE•KUHi y �l Sw �•u+-J �{ <br /> l 4 Er A550CIATtS INC. 1 <br />