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at a depth of 45 feet bsg or in samples analyzed from the three other probmgs Soil probe boring installations were described in theAGE-prepared Preliminary Site Assessment Report in August ' 1997 One 20,000-gallon UST was installed at the site following the 1998 UST removals Approximately 341 tons of hydrocarbon-impacted soil were excavated during removal of the old USTs and overexcavation for the installation of the new UST and piping Soil was disposed at Forward Landfill During the UST installation, two conductor casings were installed through the pea gravel Iadjacent to the UST in anticipation of future site assessment need The UST removal,overexcavation and UST installation were described in the AGE-prepared UST Removal Report,dated 26 May 1998 ' Three ground water monitoring wells were installed in December 1998 as part of site assessment activities Petroleum hydrocarbon-impacted soil was encountered in all well borings The maximum concentration of TPH-g was 4,200 mg/kg(MW-1) Benzene and MTBE were detected only in soil sample MW2-35 at 0 0058 mg/kg and 0.011 mg/kg, respectively ' TPH-g was detected in initial ground water samples collected from MW-1 through MW-3 at a maximum concentration of 330,000 micrograms/liter (µg/1) In the sample from MW-3 BTEX compounds were detected at concentrations as high as 29,000 µg/l, 54,000 gg/l, 6,500 µg/1 and ' 36,000 gg/l, respectively (MW-3) MTBE was detected in all three well samples at a maximum concentration of 510 µg/1 (MW-1) In addition, TBA was detected in MW-1 and MW-2 at a maximum concentration of 830 gg/1 (MW-1) Monitoring well installation and initial monitoring activities were described in the AGE-prepared Monitoring Well Installation Report, dated 02 June 1999 ' Between February and November 2001,AGE advanced five paired cone penetrometer testing(CPT) soil borings (CPT-1 through CPT-5) at the site to depths between 100 and 150 feet bsg to assess the extent of petro leum-impact and to identify potential hydrologic units TPH--g was detected in grab water samples at concentrations as high as 14,000 gg/l(CPT-4),BTEX compounds at concentrations as high as 4,000 gg/l benzene(CPT-4),MTBE concentrations as high as 1 3 µg/l(CPT-4),and TBA at concentrations as high as 5 0 µg/1 (CPT-2) ' Based on CPT data, AGE identified a vadose zone and six potential hydrologic units informally identified as Hydrologic Unit 1 (HUI), located between 30 and 70 feet bsg, Hydrologic Unit 2 ' (HU2), located between 70 and 85 feet bsg, Hydrologic Unit 3 (HU3), located between 85 and 95 or 100 feet bsg, Hydrologic Unit 4 (HU4), located between 95 or 100 feet and 120 feet bsg, ' Hydrologic Unit 5(HU5), located between 120 feet and approximately 135 feet bsg,and Hydrologic Unit 6(HU6), located between 135 feet and at least 150 feet bsg Geologic cross sections A-A'and B-B' were generated from the CPT data, depicting the informal hydrologic units and petroleum hydrocarbon concentrations beneath the site Results of the February 2001 investigation were reported in Cone Penetrometer Testing (CPT) ' Report - February 2001, dated 19 rune 2001, results of the November 2001 investigation were reported in Cone Penetrometer Testing(CPT)Report-November 2001, dated 25 March 2002 ' Advanced GeoEnvironmental,Inc