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26 December 2001 , <br /> AGE-NC Project No 96-0235 <br />' Page 2 of 5 <br />' 2 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from each purged well using new disposable plastic bailers Each <br /> water sample was transferred into 40-nil VOA vials containing 0 5 ml 18% hydrochloric acid as a <br /> sample preservative and into 1-liter amber bottles without preservative After collection,the samples <br /> were properly labeled, placed in a chilled container and transported under chain-of-custody to <br />' McCampbell Analytical, Inc (MAI), a State of California Department of Health Services (DHS)- <br /> certified analytical laboratory, and were analyzed for <br />' Total petroleum hydrocarbons quantified as gasoline (TPH-g) and as diesel (TPH-d) in <br /> accordance with EPA Methods 5030/8015 and 355018015, respectively, <br />' Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether <br /> (MTBE) in accordance with EPA Method 602/8020, and <br />' Fuel oxygenates - di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), MTBE, <br /> tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), methanol, ethanol, ethylene <br /> • dibronude(EDB) and 1,2-chchloroethane(1,2-DCA) m accordance with EPA Method 8260 <br />' Modified <br />' 3.0. FINDINGS <br /> Ground water elevation and flow direction were mferred from field data, hydrocarbon-impact to <br /> groundwater was quantified by laboratory analysis of the groundwater samples Field observations, <br /> results of laboratory analysis of ground water samples and a discussion of data collected during field <br /> work follows <br /> 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION , <br /> The casing elevation of each well was previously surveyed relative to a City of Stockton bench mark <br />' The elevation of ground water in each well was calculated by subtracting the depth to ground water <br /> from the surveyed casing elevations (Table 1) Depths to`ground water ranged from 17 75 feet to <br /> 20 47 feet below the tops of the well casings Ground water elevations at the site ranged from v <br />' -12 57 feet in MW-4 to - 13 99 feet below mean sea level (MSL) in MW-2 The average ground <br /> water elevation decreased approximately 0 75 feet in the wells <br /> lieTo infer ground water flow direction, the ground water elevation data was divided into two sets " <br /> based on the well screen intervals Ground water was between 19 57 and 21 62 feet above the' <br /> screened intervals in monitoring wells MW-1, MW-2, MW-6B, MW-8B, MW-9, MW-1113, <br /> Advanced GeoEnvmronmental,Inc <br /> 1 ' <br />