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17 June 2005 <br /> • AGE-NC Project No 97-0351 <br /> ' Page 2 of 4 <br /> ' after allowing the wells to achieve a minimum 80% recovery of the pre-purge water volume The <br /> samples from each well were transferred into three 40-milliliter(ml)volatile organic analysis(VOA) <br /> vials containing 0 5 ml 18%hydrochloric acid solution as a sample preservative The samples were <br /> Iabeled with the momtonng well designation,date,time of sampling,and the sampler's initials and <br /> transported in a chilled container under chain of custody to Cal Tech Environmental Laboratones <br /> (CTEL), a Department of Health Services (DHS)-certified analytical laboratory, for analysis The <br /> ' samples were analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> method 8015M, and <br /> • Benzene,toluene, ethylbenzene, and total xylenes(BTEX) and fuel additives tertiary butyl <br /> ' alcohol (TBA), di-isopropyl ether (DIPS), ethyl tertiary-butyl ether(ETBE), tertiary-amyl <br /> methyl ether(TAME), methyl tertiary-butyl ether(MTBE), 1,2-dibromoethane(EDB),and <br /> 1,2-dichloroethane (1,2-DCA) in accordance with EPA method 8260B <br /> ' 3.0. FINDINGS <br /> Ground water elevation and flow direction were inferred from field data, hydrocarbon impact to <br /> ground water was quantified by laboratory analysis of the ground water samples <br /> 1 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION <br /> The elevation of ground water in each of the monitoring wells was calculated by subtracting the <br /> ' depth to ground water from the surveyed relative casing elevations(Table 1) Depth to ground water <br /> ranged from 7 81 feet(MW-2)to 8 92 feet(MW-5)below the tops of the well casings Ground water <br /> elevation at the site ranged from 120 feet(MW-4)to 1 87 feet(MW-3)above mean sea level(MSL) <br /> ' and averaged approximately 156 feet above MSL, indicating a decrease in elevation of <br /> approximately 0 12 feet since the last ground water monrtonng event in January 2005 During this <br /> monitoring event the ground water elevations were within the screened intervals of the wells, <br /> ' indicating that the wells are screened properly to yield ground water samples representative of <br /> shallow ground water conditions <br /> ' Ground water in the western portion of the site was inferred to be flowing in a southeast trending <br /> trough under an average calculated gradient of approximately 0 006 foot/foot (ft/ft) Ground water <br /> ' on the eastern portion of the site was inferred to be flowing toward the southeast under a gradient <br /> of approximately 0 005 Rift Figure 3 illustrates the contoured ground water elevations as measured <br /> on 18 April 2005 <br /> Advanced GeoEnvironmental,Inc <br /> 1 <br />