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1 <br /> ' 31 March 2006 <br /> . AGE-NC Project No 97-0351 <br /> ' Page 2of4 <br /> samples from each well were transferred into three Environmental Protection Agency (EPA)- <br /> approved, 40-milliliter (ml) volatile organic analysis (VOA) vials containing 0 5 ml 18% <br /> hydrochloric acid solution as a sample preservative The samples were labeled with the monitoring <br /> well designation, date, time of sampling, and the sampler's initials and transported in a chilled <br /> ' container under chain of custody to Cal Tech Environmental Laboratories(CTEL),a Department of <br /> Health Services(DHS)-certified analytical laboratory,for analysis The 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, hydrocarbon impact to <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) Depths to ground water <br /> ranged from 5 94 feet(MW-2)to 6 97 feet(MW-5)below the tops of the well casings Ground water <br /> ' elevation at the site ranged from 2 59 feet(MW-7)to 3 97 feet(MW-1)above mean sea level(MSL) <br /> and averaged approximately 3 37 feet above MSL, indicating an increase in elevation of <br /> approximately 2 5 feet since the last ground water monitoring event in October 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 near the former east UST location was inferred to be flowing outward from a <br /> ' southwest-trending ground water ridge over well MW-I under hydraulic gradients between <br /> 0 009 foot/foot (ft/ft) and 0 01 ft/ft Ground water near the former west UST location was inferred <br /> to be flowing inward toward a depression in the potentiomentric surface near well MW-7 under <br /> ' hydraulic gradients between 0 006 ft/ft and 0 01 ft/ft Figure 3 illustrates the contoured ground water <br /> elevations as measured on 05 January 2006 <br /> • <br /> ' Advanced GeoEnvironmentsi,Inc <br />