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r04 January 2006 <br /> AGE-NC Project No 97-0351 <br /> ' Page 2 of 4 <br /> after allowing the wells to achieve a minimum $0% 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 /> ' labeled with the monitoring 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 Laboratories <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 (DIPE), 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, impact hydrocarbon act to <br /> Y P <br /> ground water was quantified 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 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 8 41 feet(MW-2)to 9 87 feet(MW-5)below the tops of the well casings Ground water <br /> elevation at the site ranged from 0 71 feet(MW-5)to 1 11 feet(MW-3)above mean sea level(MSL) <br /> and averaged approximately 0 87 feet above MSL, indicating a decrease in elevation of <br /> approximately 0 70 feet since the last ground water monitoring event in July 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 at the eastern portion of the site was inferred to be flowing toward the southeast under <br /> a hydraulic gradient of approximately 0 004 foot/foot (ft/ft), while ground water at the western <br /> portion of the site flowed towards a north-west plunging trough in the potentiometric surface under <br /> ' calculated gradients of between 0 003 ft/ft and 0 009 ft/ft Figure 3 illustrates the contoured ground <br /> water elevations as measured on 1$ October 2005 <br />� ' Advanced GeoEnvironmental,Inc <br />