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09 July 2001 <br /> AGE-NC Project No. 98-0520. <br /> ' Page 2 of 4 <br /> container and transported under chain-of-custody to McCambell Analytical,Inc.(MAI).The samples <br /> were analyzed for: <br /> ' Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 5030/8015M; <br /> • Volatile aromatic compounds-benzene,toluene, ethyl benzene and xylene(BTEX)and for <br /> ' methyl teriiarybutyl ether(MTBE) - in accordance with EPA Method.8020; and <br /> • Fuel oxygenates,including tertiarybutanol(TBA),di-isopropyl ether(DIPE),,ethyl tert-butyl ' <br /> '. ether (ETBE), tert-amyl methyl ether (TAME), and MTBE, with 1,2-Dichloroethane. <br /> (1,2-DCA) in accordance with EPA Method 8260B. . <br /> 3.0. FINDINGS <br /> Ground water elevation, and flow direction were calculated from field data;hydrocarbon-impact to . <br /> ground water was inferred from laboratory analysis of.groundwater 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 groundwater ranged from 18.91 feet to <br /> ' 19.71 feet below the tops of the well casings. Ground water elevations at the site ranged'from 17.33 <br /> "feet (MW-3) to 17.44 feet'(MW-4) above mean sea level. ' <br /> ' The ground water flow direction was determined using ground water elevation data. The ground <br /> water table underlying the site formed a trough-like depression,with the base of the trough plunging. <br /> northwest under an average gradient of 0.0006 ft/ft. The northern limb of the trough flows west- <br /> ' southwest; the southern limb's flow direction is north-northeast. At such a low gradient, small <br /> measurement'variations can greatly affect the inferred flow•direction. Figure 2' illustrates the <br /> ' contoured ground water elevations as measured on 11 June 2001. <br /> 3.2. ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in all the water samples at concentrations ranging from 640 micrograms per liter <br /> ' (µg/l) in MW-4 to 14,000 µg11 in MW-5. <br /> Advanced GeoEnvir nmenta i,Inc. <br /> a <br />