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v ATC f ASSOCIATES I N C . �r 3.0 SUBSURFACE CONDITIONS r- 3.1 Geology Lean clay, lean clay with sand, and clayey sand was encountered in soil borings SB8, SB9, and MW4 from the surface to depths between 14 feet bgs and 16 to 21 feet bgs. Soil in borings S138 and SB9 consisted of poorly graded sand from depths between 14 feet bgs and 16 to 21 feet bgs. Soil in boring MW4 consisted of, poorly graded gravel, lean clay, and poorly graded sand with silt from 16.5 to 20 feet bgs and 26.5 feet bgs. Soil from borings S1310, MW5, and MW6 generally consisted of lean clay from the surface to depths between 6 to 15 feet bgs. Soil from borings SB 10, MW5, and MW6 generally consisted of poorly and well graded sand, clayey sand and silty sand from depths between 6 to 15 feet bgs to 26.5 to 31 feet bgs. Soil in boring SB 12 consisted of poorly graded sand and silty sand from depths between 30 feet z. bgs and 45 feet bgs. Soil in boring SB 12 consisted of lean clay with sand from depths between 45 feet bgs and 46.5 to 50 feet bgs. Soil in boring SB 12 consisted of well graded sand from ` depths between 46.5 to 50 feet bgs and 51.5 feet bgs, the maximum depth explored. Soil boring logs with a detailed description of soil types are contained in Appendix A. 3.2 Hydrogeology Water level measurements were collected from wells MW1 through MW5 on June 7, 2000. Water levels ranged from 5.64 to 11.09 feet below the tops of the well casing elevations. The water level data were used to develop the groundwater elevation contour map (Figure 3). Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer i beneath the site flowed towards the southwest. The average hydraulic gradient on June 7, 2000 was calculated to be 0.001 ft/ft or approximately 5.3 ft/mile. A summary of groundwater monitoring data is presented in Table 3. 4.0 ANALYTICAL RESULTS 4.1 Soil Analytical Results Soil samples collected from borings S138, SB9, and SB 10 contained no detectable concentrations of TPHd, TPHg, BTEX, or oxygenate fuel additives. Soil samples collected from boring MW4 at depths of 15.5 feet and 25.5 feet bgs contained no detectable concentrations of TPHd, TPHg, BTEX, or MTBE. The soil sample collected from boring MW4 at a depth of 20.5 feet bgs LM contained TPHd and TPHg at concentrations of 1,100 parts per million (ppm) and 85 ppm, --ftwol respectively. The soil sample collected from boring MW4 at a depth of 20.5 feet bgs contained L no detectable concentration of total lead. The soil samples collected from borings MW5, SB 12, wA54.62500Veponslsumiii.doc 6 r LW