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_ f 30 March 2004 AGE-NC Project No 02-0962 ' Page 6 of 7 ' Site assessment activities to date defined two areas where soil is Impacted by concentrations of petroleum hydrocarbons The highest petroleum-hydrocarbon concentrations, up to 110 mg/kg _ TPH-d,were detected adjacent to the former pipping sample location P 13 Petroleum hydrocarbons, I up to 110 mg/kg, were detected at 15 feet bsg in soil probe boring B3 (Figure 2) Petroleum hydrocarbons were also detected In soil samples collected from boring B7 at 30 feet bsg at concentrations of 12 mg/kg, adjacent to pipping sample P7 ISite assessment activities to date defined an area where ground water is impacted by high concentrations of petroleum hydrocarbons The highest petroleum-hydrocarbon concentrations, up I to 2,200,000 gg/l TPH-d,were detected in grab groundwater samples adjacent to the former pipping sample location P13 Petroleum hydrocarbons, up to 190,000 gg/l, were detected in grab ground water samples just north of dispenser DI(Figure 2) MTBE was detected In minor concentrationsjust north of dispenser sample D7 Based on AGE's Interpretation of the available data,the initial release(s)of petroleum hydrocarbons occurred from the former dispensers and associated pipping prior to their removal in 2003 Once released to the subsurface, the contaminants migrated through the clayey silt material to a vertical ' depth of approximately 20 feet bsg, at which point the contaminants encountered very permeable silty sand to fine grained,sand (Unit 2) and began to migrate laterally, lateral migration was dominantly towards the north to northeast, in the direction of ground water flow 6.0 SUMMARY AND CONCLUSIONS IBased on the data collected from the site in this, AGE finds • Clay and silt occurred under most of the site, with the exception of an apparently laterally continuous sand unit at between 25 feet and 30 feet bsg Ground water occurred at approximately 20 and 25 feet bsg during the October 2003 boring event ' • Significant concentrations of both TPH-g/d were detected in grab ground water samples collected In the northern dispenser area`The lateral extent of TPH-g/d contamination Is not yet defined to the north and west of the release The vertical extent of TPH-g/d contamination Is not yet defined MTBE was only detected in minor concentrations In groundwater samples collected from boring B5 • Concentrations of TPH-g/d were detected In soif samples collected from borings B3 and B7 The lateral extent of TPH-g/d contamination In soil Is defined In all directions with the exception of the area south of boring B7 The vertical extent of TPH-g/d contamination is Inot yet determined In any direction Advanced GeoEnvi ron mental,Inc