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' 11 June 2001 AGE-NC Project No. 96-0232 ' Page 2 of 11 In September 1998,two 4,000-gallon USTs, one 550-gallon UST and associated dispensers/product ' piping were removed from the site (see Figure 2). TPH-g was detected beneath the USTs at concentrations as high as 8,200 mg/kg; BTEX compounds were detected beneath the USTs at ' concentrations ranging as high as 1,400 mg/kg.The fuel oxygenated compounds methyl tertiary butyl ether(MTBE),tert-amyl methyl ether(TAME)and tert-butanol(TBA)were detected in soil beneath the USTs at concentrations ranging as high as 13 mg/kg. 2.3. PREVIOUS INVESTIGATION The following is a summary of previous investigations at the site of the unauthorized release of fuel products to the subsurface: ' • 28&29 December 1994-Five soil borings(B-1 through B-5)were advanced at the site near ' the former UST area. Soil borings B-1, B-3 and B-5 were advanced to depths of 35 feet; B-2 and B-4 were advanced to depths of 65 feet. Petroleum hydrocarbon impacted soil was encountered in all five soil borings at depths between 10 feet and 65 feet (Table 1). Results ' of the December 1994 investigation were reported in Preliminary Investigation and Evaluation Report(PIER), dated 10 April 1995,prepared by Geological Audit Services, Inc. • 09& 10 January 1995- Four soil borings (MW-1, MW-2, MW-3 and B-6) were advanced ' at the site as part of the ongoing investigation. Soil boring B-6 was advanced to a depth of 65 feet; MW-1 through MW-3 were advanced to depths of 80 feet and completed as 2-inch ' diameter ground water monitoring wells. Petroleum hydrocarbon impacted soil was encountered in all four soil borings at depths between 35 feet and 65 feet.Dissolved TPH-g and BTEX compounds were detected in initial ground water samples from all three wells at concentrations up to 11,000 µg/1 (Tables 1 and 2). 'Results of the December 1994 investigation were reported in Preliminary Investigation and Evaluation Report(PIER)dated 10 April 1995, prepared by Geological Audit Services, Inc. ' • 05, 06, 07& 08 December 1995-Three soil borings (VW-1 through VW-3)were advanced near the former UST area and one soil boring (MW-4) was advanced downgradient of the former UST area. Soil borings VW-1 through VW-3 were advanced to depths of 63 feet and ' completed as soil vapor extraction(SVE)wells. Soil boring MW-4 was advanced to a depth of 75 feet and completed as a 2-inch diameter ground water monitoring well. Hydrocarbon- impacted soil was encountered in all three SVE wells at depths of 15 feet to 60 feet; no petroleum hydrocarbons were detected in soil samples collected from MW-4. Dissolved TPH-g was not detected in initial ground water samples collected from MW-4. However, ' TPH-g and benzene were detected in MW-4 in later sampling events at concentrations as high as 78 µg/1 and 10 µg/1, respectively(Tables 1 and 2). Results of the December 1995 investigation were reported in Corrective Action Plan(CAP),dated 20 March 1996,prepared ' Advanced GeoEnvironmental,Inc.