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1 <br /> i 30 September 1999 <br /> ' AGE-NC Project No 97-0351 <br /> Page 2 of 4 <br /> ' 40-m1 EPA-approved volatile organic analysis (VOA) vials containing 0 5 ml hydrochloric acid <br /> (18%) as a sample preservative and additional sample from each well was transferred into chilled <br /> ' 1-liter amber bottles The samples were labeled individually and placed in a chilled container and <br /> transported under chain-of-custody to McCampbell Analytical,Inc (MAI), a California Department <br /> of Health Services(DHS)-certified analytical laboratory located in Pacheco, California Each sample <br /> ' was analyzed in accordance with ' <br /> • EPA Method 8015m for total petroleum hydrocarbons quantified as gasoline (TPH-g), <br /> • EPA Method 8015m for total petroleum hydrocarbons quantified as diesel (TPH-d) <br /> • EPA,Method 8020 for volatile aromatic compounds (benzene, toluene, ethylbenzene and <br /> ' total xylenes BTEX) and methyl tertiary-butyl ether(MTBE), <br /> • EPA Method 8260m for dl-isopropyl ether(RIPE), ethyl tertiary butyl ether(ETBE), methyl <br /> ' tertiary butyl ether(MTBE), tertiary amyl methyl ether (TAME) and tertiary butyl alcohol <br /> (TBA) <br /> 3.0. FINDINGS <br /> ' Ground water flow direction and gradient were determined from field measurements, hydrocarbon <br /> impact on ground water was assessed from results of laboratory analysis <br /> ' 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> ' The relative elevation of ground water in each well was calculated by subtracting the ground water <br /> depth from the surveyed relative casing elevation The wells were surveyed relative to the top of well <br /> MWA, with an arbitrary elevation of 10 feet above mean sea level The relative ground water <br /> ' elevation data is summarized in Table 1 <br /> Ground water flow direction in the area from the western UST was toward the northeast at a gradient <br /> of approximately 0 0005 (ft/ft) and the flow direction appears to switch toward the northwest as <br /> observed in the area of Building E as depicted in Figure 3 <br /> ' The close proximity of the western UST area to the Stockton Deep Water channel may have a <br /> significant effect on the localized flow and gradient on the site Contoured ground water elevations <br /> ' are shown in Figure 3 <br /> ' Advanced GeoEn<<ronmental,Inc <br />