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I I10 December 2001 • AGE-NC Project No 96-0249 IPage 3 of 6 (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and MTBE by EPA Method 8260 Modified 30 FINDINGS Ground water elevation, flow direction and gradient were determined from field data collected on 05 September 2001, the contaminant impact to ground water was assessed from the ground water laboratory data collected on 06 September 2001 3 1 GROUND WATER ELEVATION AND GRADIENT The depths to ground water in wells MW-1 through MW-6 vaned from 15 41 to 18 02 feet below the tops of the well casings, ground water elevations were calculated to be between 7 84 feet and 8 64 feet below mean sea level Ground water elevation at the site decreased an average 3 60 feet between the June 2001 and the September 2001 ground water monitoring events The ground water lieelevation data for MW-1 through MW-6 during the September 2001 ground water monitoring event is depicted in Figure 3 Ground water flow direction in the area bound by Three B's Truck Plaza wells MW-1 through MW-6 was inferred to be towards the west at a gradient of 0 004 ft/ft or less, or approximately 21 feet per mile (Figure 3) 3 2 LABORATORY RESULTS OF MONITORING WELL GROUND WATER SAMPLES A total of sixground water samples were submitted to a DHS-certified laboratoryin September 2001 TPH-g was detected in water samples collected from wells MW-1, MW-2,MW-3, MW-5 and MW-6 at concentrations ranging between 580 and 8,100 micrograms per liter (ug/l), the laboratory reported each TPH-g chromatogram as having unmodified or weakly modified gasoline patterns TPH-d was detected in water samples collected from MWA, MW-2, MW-3 and MW-6 at concentrations ranging between 200 and 2,200,ug/l, however, the laboratory noted that the diesel range hydrocarbons in the samples had non-diesel patterns and the samples contained significant lighter gasoline range compounds BTEX compounds were detected in water samples collected from MW-1,MW-2,MW-3,MW-5 and MW-6 at concentrations ranging as high as 1,700,ug/l (benzene, MW-3), MTBE was detected in the • water sample collected from MW-4 at a concentration of 110 ,ug/l by the EPA 8020 analysis Advanced GeoEnvironmental,Inc