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03/16/2001 11:33 2094671 AGE STOCKTON PAGE 05 12 March 2001 AGE-NC Project No. 97-0333 Page 2 of 8 at concentrations ranging up to 2,600 milligrams per kilogram(mg/kg);in soil from beneath the west ends of the USTs at concentrations ranging up to 25 mg/kg; and in soil from beneath product piping at concentrations ranging to 8,000 mg/kg. Volatile aromatics compounds-benzene,toluene, ethylbenzene and xylenes(BTEX)were detected in soil from beneath the east ends of three USTs at concentrations ranging up to 340 mg/kg;beneath the west ends of the USTs at concentrations ranging up to 2.7 mg/kg; and beneath product piping at concentrations ranging up to 880 mg/kg. Fuel oxygenated compounds-methyl tertiary butyl ether(MTBE),tert-amyl methyl ether(TAME) and tert-butanol (TBA) were detected in soil from beneath the east ends of the three USTs at concentrations ranging up to 16 mg/kg;beneath the west ends of the USTs at concentrations ranging up to 3.1 mg/kg; and beneath product piping at concentrations ranging up to 690 mg/kg. 2.3. PREVIOUS SUBSURFACE INVESTIGATION The following is a summary of previous investigations at the site of the unauthorized release of fuel products to the subsurface: 15 April 1999 - Six soil borings (P-1 through P-6) were advanced at the site to assess the lateral and vertical extent of petroleum-impacted soil and ground water. A total of 17 soil samples and five ground water samples were collected during the investigation and were submitted for laboratory analysis. TPH-g and total petroleum hydrocarbons quantified as diesel (TPH-d) were detected in analyzed soil samples at concentrations as high as 390 mg/kg; dissolved TPH-g and TPH-d were detected in grab ground water samples at concentrations ranging as high as 310,000 micrograms per liter(ug/l). BTEX compounds were detected in selected soil samples and grab ground water samples at concentrations as high as 51 mg/kg and 48,000µg/1, respectively. MTBE, TAME and TBA were detected in selected soil samples and grab ground water samples at concentrations as high as 0.36 mg/kg and 310,000 µg/l. Results of the April 1999 investigation were reported in Preliminary Investigation and Evaluation Report(PIER) dated 11 June 1999 prepared by AGE. • 29 June 2000- Ground water monitoring wells MW-1, MW-2, MW-3, MW-4 and MW-5 were installed on- and off-site to assess the lateral and vertical extent ofpetroleum-impacted soil and ground water. A total of seventeen soil samples were collected during drilling activities and submitted to a DHS-certified laboratory for analysis for TPH-g,BTEX,MTBE, ETBE, TAME,DIPE, TBA, 1,2-DCA,EDB,methanol and ethanol. TPH-g was detected in soil samples collected from borings MW-1, MW-2 and MW-4 at concentrations as high as 85 mg/kg; BTEX compounds were detected in soil samples collected from MW-1, MW-2 and MW-4 at concentrations as high as 6.7 mg/kg; MTBE and TAME were detected in soil Advanced GwEnvironmental,Inc.