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26 February.2003 <br /> AGE-NC Project No.-98-0520 <br /> 1 Page 2 of 4 <br /> 1 hydrochloric acid as a sample preservative. After collection,-the samples were properly labeled, <br /> --placed in a chilled container and transported under chain-of=custody to Cal Tech Environmental <br /> Laboratories .(CTEL), a California Department of Health Services (DHS)-certified analytical <br /> 1 laboratory, for analysis. The samples were,analyzed for: <br /> •. Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 8015M; . <br /> • Benzene, toluene, ethyl benzene and xylene (BTEX),and fuel additives; including methyl <br /> tertiary-butyl.ether(MTBE),tertiary butanol (TBA), di--isopropyl ether(DIPS), ethyl'tert-. <br /> butyl ether(ETBE),tert-amyl methyl ether(TAME), 1,2-dichloroethane(1,2-DCA)and 1,2- <br /> dibromoethane (EDB) in'accordance with EPA Method 8260B. <br /> 3.0. FINDINGS . <br /> Ground water elevation and flow.direction were determined frorn field data. Hydrocarbon-impact <br /> to ground water wasquantified from laboratory analysis of the ground water samples. <br /> 3.1. GROUND WATER ELEVATION AND GRADIENT <br /> The elevation.of ground water in each well was calculated by subtracting the depth to.ground water <br /> 1 from the surveyed casing elevations (Table 1). Depths to ground water ranged from 19.88 feet to <br /> 21.13 feet-below the tops,of the well casings(btoc). Ground water elevations at the site ranged from <br /> 15.84 feet (MW-9) to 16.25 feet(MW-10) above mean sea level. <br /> 1 The ground water flow direction was determined using ground water elevation data from water table <br /> -wells MW-1 through MW-5, MW-7, MW-9 and MW-10; elevation data from well MW-6 was not <br /> utilized because well MW-6 is a deep-screen well. The ground water table underlying the site is <br /> inferred to be flowing northwest under an average gradient of 0.002 ft/ft. Figure 3. illustrates the E. <br /> contoured ground watei elevations as measured on 16 December 2002, <br /> 31 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> ' TPH-g was.detected in the water samples collected from wells MW-.1, MW-2, MW-3 and MW-5, <br /> at concentrations ranging from 340 micrograms per liter (µg/l) in MW-1 to 1,900 pg/l in MW-5. <br /> 1 Figure 4 illustrates the approximate distribution of dissolved TPH-g. ; <br /> Advanced GeoEnvironmental,Inc. <br />