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22 December 1998 <br /> AGE-NC Project No 97-0312 <br /> Page 2 of 4 <br /> sample preservative and into one 1-liter amber bottle without preservative The samples were <br /> labeled, placed in a chilled container and transported to McCampbell Analytical, Inc (MAI), a <br /> California Department of Health Services (DHS)-certified laboratory in Pacheco, California The <br /> samples were analyzed for <br /> Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in <br /> accordance with EPA Methods 5030 and 8015m, <br /> Volatile aromatic compounds (benzene, toluene, ethylbenzene and xylenes BTE&X) and <br /> methyl tertiary-butyl ether(MTBE) in accordance with EPA Method 602/8020, and <br /> Volatile organic compounds with oxygenated compounds (methyl tertiary-butyl ether <br /> [MTBE], dt-isopropyl ether [DIPE], ethyl tert-butyl ether [ETBE], tert-amyl methyl ether <br /> [TAME] and tert-butanol [TBA]) In accordance with EPA Method 8260 modified <br /> 30. FINDINGS <br /> 3 1 GROUND WATER ELEVATION AND GRADIENT <br /> The elevation of ground water in each well was calculated by subtracting the depth to water from <br /> the surveyed casing elevation (Table 1) The ground water elevation deci eased an average of 7 77 <br /> feet since the June 1998 monitoring g event Down-gradient wells showed a smaller decrease in <br /> ground water elevation, while upgradrent wells showed a larger decrease in elevation The ground <br /> water flow direction was inferred to be northeasterly with a gradient of 0 0014 ft/ft The flow <br /> direction Is similar to previous monitoring events Figure 3 - Ground Water Elevation depicts the <br /> contours for September 1998 <br /> Static ground water was approximately nine feet above the screened interval in UST-2, UST-3 and <br /> UST-4 Drawdowns of 16 feet, 2 7 feet and 1 8 feet were achieved during purging of UST-2,UST-3 <br /> and UST-4, respectively Ground water was within the screened interval in UST-5 A recharge of <br /> 100 percent was measured in each well prior to sample collection <br /> 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g and TPH-d were detected in the sample collected from monitoring well UST-5 at <br /> concentrations of 680 parts per billion (ppb, reported as micrograms per Mer) and 200 ppb, <br /> respectively Benzene, toluene, ethylbenzene and xylenes were detected in this sample at <br /> concentrations of 13 ppb, 4 4 ppb, 0 87 ppb and 0 93 ppb, respectively Petroleum hydrocarbons <br /> Advanced GeoEnvi ron mental,Inc <br />