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31 March 2006 AGE-NC Project No. 98-0471 Page 7 of 13 hydrocarbons have not been detected in wells peripheral to well MW-3, located in the former 1,000-gallon gasoline AST area, since May 2003. Historically, petroleum hydrocarbon-impacted ground water has been detected consistently only in monitoring wells MW-1 and MW-3, with occasional detections in wells MW-2 and MW-4.Monitoring wells MW-5 and MW-6 have remained uncontaminated; with the exception of the initial ground water sample after well installation. Petroleum hydrocarbons have not been detected in well MW-7 since the initial ground water monitoring event conducted in September 2002. Drinking water at and near the site is supplied by domestic water wells.The nearest well is located on-site,approximately 130 feet northwest(up-gradient)from monitoring well MW-3;it has not been impacted and, based on the lateral extent of contaminated ground water at the site, it is unlikely to be impacted by contaminated ground water. 6.0. PETROLEUM HYDROCARBON DISTRIBUTION IN SOIL The majority of petroleum hydrocarbon-impacted soil appears to be limited to the area near the former 1,000-gallon gasoline AST. The highest petroleum hydrocarbon concentrations in soil were detected in samples TI-E, Tl-W, and TI-N, collected in July 1998 approximately 10 feet north- northwest of the former AST at a depth of 2 feet bsg; SW-6, collected in December 1999 immediately south of the former AST at a depth of 6 feet bsg;and SE-6,collected in December 1999 approximately 5 feet east of the former AST at a depth of 6 feet bsg (Figure 2). In sample T1-E (sample location removed during 8-foot excavation activities),TPH-g and TPH-d were detected at concentrations as high as 19,000 mg/kg and 10,000 mg/kg, respectively; BTEX compounds were detected at maximum concentrations of 180 mg/kg benzene, 1,700 mg/kg toluene, 480 mg/kg ethylbenzene, and 1,800 mg/kg xylenes. MTBE was detected in sample SW-6 at a maximum concentration of 30 mg/kg. (Table 1). Based on assumptions of average concentrations of analytical results for soil samples collected from trenching and excavation activities and soil borings between July 1998 and May 2001, AGE calculated the mass of TPH-g,TPH-d,TPH-mo,MTBE,and BTEX remaining in the predominantly silty and sandy soil: • An estimated 123.1 pounds (lbs), or 19.7 gallons, of TPH-g remain in soil; • An estimated 163.3 lbs, or 23.3 gallons, of TPH-d remain in soil; • An estimated 65.3 lbs, or 0.9 gallons, of TPH-mo remain in soil; • An estimated 0.4 lbs, or 0.1 gallons, of MTBE remain in soil; • An estimated 1.6 lbs, or 0.2 gallons, of benzene remain in soil; Advanced GeoEnvironmental,Inc