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16 September 2003 <br /> AGE-NC Project No 98-0452 <br /> Page 2 of 4 <br />' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES <br /> Water samples were collected from each momtonng well using new disposable bailers after allowing <br />' the wells to achieve a minimum 80% recovery of the pre-purge water volume Each water sample <br /> was transferred into laboratory-supplied 40-m1 volatile organic analysis(VOA)vials containing 0 5 <br /> ml 18% hydrochloric acid as a sample preservative Ater collection, the samples were properly <br />' labeled, placed in a chilled container and transported under chain-of-custody to Cal Tech <br /> Environmental Laboratories (CTEL), a California Department of Health Services(DHS)-certified <br /> analytical laboratory, and analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 8015 Modified, and <br />' • Benzene,toluene,ethylbenzene and xylenes(BTEX), and the fuel additives methyl-tertiary- <br /> butyl-ether (MTBE), tertiary butyl alcohol (TBA), di-isopropyl ether (RIPE), ethyl tertiary <br />' butyl ether(ETBE), and tertiary amyl methyl ether(TAME), 1,2-dibromoethane(EDB) and <br /> 1,2-dichloroethane (1,2-DCA) in accordance with EPA Method 8260B <br /> 1 <br /> 3.0. FINDINGS <br />' Ground water elevation and flow direction were calculated from field data The impact to ground <br /> water was assessed by laboratory analysis of the ground water samples <br /> 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION <br /> The elevation of ground water in each well was calculated by subtracting the depth to ground water <br /> from the surveyed well head elevations (Table 1) Depths to ground water ranged from 4 45 feet to <br /> 5 45 feet below the tops of the well casings Ground water elevations at the site ranged from <br /> 107 feet(MW-3)to 125 feet(MW-2)below mean sea level(MSL) The ground water gradient was <br /> calculated to be approximately 0 017 feetlfeet with a flow direction toward the southwest(Figure 3) <br /> Average ground water elevation was 1 19 feet below MSL and decreased an average of 0 09 feet <br /> between the March 2003 and this monitoring event <br /> Advanced GeoEnviranmental,Inc <br /> 1 <br />