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August 30, 2000 <br /> Mr. Ed Ralston <br /> Page 3 <br /> not collected from boring GP-2, located within the area of overexcavation, <br /> until a depth greater than 30 feet bgs. All work was done in accordance with <br /> stipulations of permits obtained from the SJCPHSIEHD. <br /> * Soil Selection and Analysis. Soil samples were collected every 5 feet until <br /> refusal at approximately 60 feet bgs. Selected soil samples were submitted to <br /> a California State-certified laboratory and analyzed for the presence of total <br /> petroleum hydrocarbons quantified as gasoline (TPH-g), benzene, toluene, <br /> ethylbenzene, and total xylenes (BTEX), and methyl tertiary-butyl ether <br /> (MtBE) by EPA Methods 8015 Modified and 8020. MtBE confirmation <br /> analysis was conducted by EPA Method 8260. No additional oxygenate <br /> analysis of soil samples was conducted based upon non-detection of D1PE, <br /> ETBE, TAME and TBA in over-excavation soil samples at depths of 11 and <br /> 13 feet bgs. Sampling and analytical methods are presented in Attachment A. <br /> • Groundwater Analysis. Groundwater samples were submitted to a California <br /> State-certified laboratory for analysis. Groundwater samples was analyzed for <br /> the presence of TPH-g, BTEX, and MtBE using EPA Methods 8015 Modified <br /> and 8020. MtBE confirmation analysis was conducted using EPA Method <br /> 8260. . <br /> FINDINGS <br /> Subsurface.Conditions <br /> Soils encountered during drilling (maximum explored depth of approximately 60 feet bgs) <br /> consisted of interbedded sands, silty sands, sandy silts, silty clays and clayey silts. A more <br /> complete description of the subsurface lithology is shown on the boring logs presented in <br /> Attachment B. <br /> Soil Analytical Results <br /> TPH-g, BTEX compounds and MtBE were all non detect at the laboratory reporting limits in <br /> samples collected from GP-1 at 30 feet and GP-3 at 40 feet. Reported concentrations of TPH- <br /> g ranged from 1.29 ppm in GP-1 at 45 feet to 4,570 ppm in GP-2 at 40 feet. Reported <br /> concentrations of benzene ranged from 6.31 ppm in GP-2 at 40 feet to 21.1 ppm in GP-3 at 60 <br /> feet. MtBE was detected in one soil sample, GP-3 at 60 feet bgs at a concentration of 26.5 <br /> ppm by EPA Method 8020. MtBE was non-detect in GP-3 at 60 feet bgs, by EPA Method <br /> 8260. Soil analytical data is summarized in Table 1 and laboratory reports with chain of <br /> custody(COC) documentation is included in Attachment C. <br /> Groundwater Analytical Results <br /> Groundwater samples were collected from GP-2 at 52 feet bgs and from GP-3 and GP-4 at 30 <br /> feet bgs. TPH-g and benzene were not reported in GP-3 and GP-4. MtBE was confirmed by <br /> N:\rancfp1\Projects\Projects\91 1101 111 A101021911011 rpt.doc <br />