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• The USTs, product piping, and dispensers were replaced during site renovation activities in February and October 1998 Avalon Environmental Consultants (Avalon) conducted compliance soil sampling for the southern tank pit on February 23, 1998, and for the northern tank pit on October 9, 1998 TPHD, benzene, and MTBE were reported in compliance samples collected from a depth of approximately 10 5 feet bgs at maximum concentrations of 660 mg/Kg, 0 88 mg/Kg, and 0 46 mg/Kg, respectively The highest reported concentrations were found beneath the northern tank pit • In November 1998, Avalon advanced fifteen soil borings in the vicinity of the former northern (GP-1 through GP-7) and southern (GP-8 through GP-15) UST pits TPHD and MTBE were reported in soil samples collected from a depth of approximately 9 feet bgs at maximum concentrations of 200 mg/Kg and 0 064 mg/Kg, respectively Avalon concluded that petroleum hydrocarbon impact extended to groundwater TPHD, benzene, and MTBE were reported in grab groundwater samples at maximum concentrations of 11,000 pg/L, 16 µg/L, and 1,700 µg/L, respectively Avalon concluded that the lateral and vertical extent of hydrocarbon impact was adequately characterized beneath the southern tank pit, but that the lateral extent of petroleum hydrocarbon impact beneath the northern tank pit had not been adequately assessed • In February 2000, Avalon installed six groundwater monitoring wells (MW-1 through MW-6) Depth to water beneath the site ranged from 6 24 to 7 26 feet bgs Avalon concluded that groundwater beneath the site was impacted with TPHD, TPHG, benzene, and MTBE at maximum concentrations of 120 µg/L, 440 pg/L, 3 1 µg/L, and 1,800 µg/L, respectively The site was subsequently placed on a quarterly groundwater-monitoring program • In January 2001, Avalon conducted additional subsurface assessment activities to further evaluate the lateral extent of petroleum hydrocarbon impact to soil and groundwater in the northern half of the site and beneath the adjacent property to the north Four soil borings (GP-1 through GP-4) were advanced along the northern border of the site, and six soil borings (GP-5 through GP-10) were advanced on the adjacent property to the north for further lateral characterization of the dissolved plume to the northeast (predominant groundwater flow direction) MTBE was reported in the grab groundwater samples collected from every boring advanced during this round of investigation activity, with the maximum reported concentration of MTBE reported at 2,600 µg/L Avalon concluded that the lateral extent of petroleum hydrocarbon impact to soil was adequately characterized However, Avalon concluded that the vertical extent of dissolved hydrocarbons beneath the site, and the lateral extent of dissolved hydrocarbons to the north and northeast were not adequately characterized by this investigation • In February 2002, Avalon installed four more monitoring wells to further evaluate the vertical the lateral extent of petroleum hydrocarbon impact to groundwater Three of these wells (MWO-1 through MWO-3) were installed in the adjacent property to the P Voe's Truck P1aza\Reports\SCM_09-2003Voes truck plaza SCM doc Page 6 STRATUS