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• 48 May 1996 AGE-NC Project No 95-0101 Page 2 of 4 of 85 feet Borings B7 and B8 were advanced to a depth of 65 feet and backfilled in the entire depth with Portland cement No petroleum hydrocarbons were detected in any of the 14 soil samples collected and analyzed from the borings or monitoring wells In April 1995, two borings were installed at the site by AGE Boring B9 was advanced to a depth of 75 feet, boring B10 was advanced to a depth of 80 feet Organic vapors were detected to soil samples collected from boring B9 from depths of 25 feet to 70 feet at concentrations of up to 646 ppm No organic vapors or hydrocarbon odors were detected in boring B 10 TPH-g was detected in sample B9-35 at a concentration of 9,100 ppm Benzene and xylenes were detected in sample B9- 45 at concentrations of 0 006 ppm and 0 006 ppm Petroleum hydrocarbons were not detected in any other soil sample analyzed Ground water samples were collected from the bottom of both borings TPH-g was detected in the water sample collected from boring B9 at a concentration of 300 ppb Only xylene was detected in the water sample collected from boring B 10 at a concentration of 0 83 ppb Boring B9 was backfilled from 80 feet to 50 feet with Portland Cement and bentonite The boring was then completed as vadose zone well VW-1 using 2-inch diameter, 0 020 slotted PVC casing from 30 feet to 50 feet Boring B 10 was backfilled in the entire depth with Portland Cement 2 3 GROUND WATER MONITORING Ground water monitoring at the site has been performed by AGS, Nations Groundwater Associates (NGA), GeoAudrt and AGE on eleven occasions between June of 1987 and May 1995 Ground water flow direction has been consistently to the southwest 2 4 UNDERGROUND STORAGE TANK REMOVAL Four USTs were removed from the site in March of 1990 Low concentrations of volatile aromatics were detected in soil samples collected beneath the tanks According to PHS-EHD records, approximately 800 cubic yards of gasoline-contaminated soil were removed from the tank excavation and stockpiled on-site In anticipation of future cleanup requirements, four-inch diameter slotted PVC casing was installed around the bottom of the excavation Approximately 5 inches of pea gravel were placed in the excavation to cover the piping Plastic sheeting was placed over this gravel, and the new USTs were installed over the plastic sheeting •