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I05 December 2002 • AGE-NC Project No 02-0964 Page 2 of 7 the map Lines of Equal Elevation of Groundwater Sprang 1998(FCD&WCD) depicts the regional ground water flow direction towards the northwest and west Review of previous ground water monitoring at the site and historical depth to ground water maps(FCD&WCD)dating back to 1971 suggests that ground water depth near the site has fluctuated between 50 feet bsg and 60 feet bsg ' 2 2 UNDERGROUND STORAGE TANK REMOVAL An unnamed service station operated at the site from the 1940's until the 1960's Reportedly four IUSTs were filled with sand and abandoned in place in the late 1960's A Standard Oil Service Station operated at the site from the 1960s until 1980 Subsequently, the USTs associated with this fuel system were removed, the location of the former USTs during this period is uncertain, but is believed to be at the northeast comer of the site Neither UST decommissioning was verified with soil sample collection 23 PREVTOUS SITE ASSESSMENTS Ten soil borings have been advanced and three ground water monitoring wells have been installed at the site to assess the vertical and lateral extent of impacted soil and ground water The following is a summary of milestone events at the site On 22 May 2000, a total of seven on-site soil borings were established by Hydro-Geo Consultants Inc with a Geoprobe sampling rig Borings A, B and C were established on the northeast corner of the site and borings D through G were established on the west and southern edge of the former service station location,to a depth of 45 feet below surface grade(bsg) Based on laboratory analysis • Total petroleum hydrocarbons as gasoline and diesel (TPH-g and TPH-d) were detected in soil samples collected during boring operations at concentrations as high as 300 milligrams per kilogram(mg/kg)and 2,400 mg/kg,respectively, in the sample from boring A at 30 feet bsg BTEX compounds were detected in the soil samples at maximum concentrations of 0 5 mg/kg(toluene), 1 5 mg/kg(ethylbenzene)and 30 mg/kg(xylenes)in the sample from boring A at 40 feet bsg • TPH-g and TPH-d were detected in grab ground water samples collected during the soil boring operations at concentrations as high as 470,000 micrograms per liter (µg/1) and 230,000 µg/1,respectively,in the sample from boring A Dissolved BTEX compounds were IAdvanced GeoEnvironmental,Inc f