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10 December 2004 <br /> AGE-NC Project No. 98-0520 <br />' Page 2 of 4 <br /> After collection, the samples were properly labeled, placed iri a chilled container and transported <br /> under chain of custody to Cal Tech Environmental Laboratories (CTEL), a State of California <br /> Department of Health Services(DHS)-certified analytical laboratory,for analysis.The samples were <br /> analyzed for: <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 8015M; and <br /> • Benzene,toluene,ethylbenzene,and xylenes(BTEX)and fuel additives methyl tertiary-butyl , <br /> ether(MTBE), tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether <br /> ' (ETBE), tertiary-amyl methyl ether (TAME), 1,2-dichloroethane .(1,2-DCA), and <br /> 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 collected on 10 <br /> September 2004. Hydrocarbon-impact to ground water was quantified from laboratory analysis of <br />.� 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 /> from the surveyed casing elevations (Table 1). Depths to ground water ranged from 25.81 feet <br /> (MW-7)to 26.89 feet(MW-2)below the tops of the well casings. Ground water elevation at the site, <br /> not including MW-6, averaged approximately 10.21 feet above mean sea level (MSL), showing an <br /> ' elevation decrease of approximately 1.56 feet since the last monitoring event. <br /> ' The ground water flow direction was determined using ground water elevation data from water table <br /> wells MW-1 through MW-5 and MW-7 through MW-9; elevation data from well MW-6 was not <br /> utilized because well MW-6 is a deep-screened well. The shape of the water table at the time of the <br /> ' September 2004 monitoring event was in the form of a northwest-plunging ridge and trough. Net <br /> flow of ground water at the site was determined to be to the northwest under a gradient of <br /> approximately 0.004 foot/foot (ft/ft) or less. Figure 3 illustrates the contoured ground water <br /> ' elevations as measured on 10 September 2004. <br /> ' Advanced GeoEnvironmentai,Inc. <br />