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10 December 2002 <br /> • AGE-NC Project No..98-0520 - <br />' Page 2 of 4 <br /> transferred into laboratory-supplied 40-m1 VOA vials containing 0.5 ml 189/o hydrochloric acid as <br /> ' a sample preservative. After collection, the samples were properly labeled, placed in a chilled <br /> container and transported under chain-of-custody to Cal Tech Environmental Laboratories(CTEL), <br /> a California Department of Health Services (DHS)-certified analytical laboratory, for analysis. The <br /> samples were analyzed for: <br /> • Total petroleum hydrocarbons quantified as gasoline (TP H=g) in accordance with EPA <br /> 1 Method 5030/8015M; <br /> • Benzene,toluene,ethyl benzene and xylene(BTEX)and methyl tertiary-butyl ether(MTBE) ' <br /> ' in accordance with EPA Method 8021; and <br /> • Fuel oxygenates,including tertiary butanol(TBA),di-isopropyl ether(DIPE),ethyl tert-butyl <br /> ether (ETBE), tert-amyl methyl ether (TAME), and MTBE, with 1,2-dichloroethane <br /> ' (1,2-DCA) and 1,2-dibromoethane (EDB) in accordance with EPA Method 8260B. <br /> 3.0. FINDINGS <br /> ' Ground water elevation and flow direction were determined from field data. Hydrocarbon-impact <br /> to ground water was quantified 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 b subtracting the depth to ground water <br /> �' Y g p <br /> from the surveyed casing elevations (Table 1). Depths to ground water ranged from 23.05 feet to <br /> ' 24.11�feet below the tops of the well casings. Ground water elevations at the site ranged from <br /> 12.67 feet (MW-7) to 13.37 feet (MW-10) above mean sea level. <br /> e <br /> ' The ground water flow direction was determined using groundwater elevation data from water table <br /> wells MW-1 through MW-5 and MW-7 through MW-10; elevation data from well MW-6 was not <br /> utilized because well MW-6 was a deep-screen well. The ground water table underlying the site <br /> ' formed a ground water mound, with the base of the mound plunging northwest under an average <br /> gradient of 0.0006 ft/ft. The western limb of the mound flows west-southwest; the eastern limb's <br /> flow direction is northeast. At such a low gradient, small measurement variations can greatly affect <br /> ' the calculated flow direction.Figure 3 illustrates the contoured ground water elevations as measured , <br /> on 18 September 2002. <br /> ' Advanced GeoEnvironmental,Inc. <br /> 1 <br />