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5.0 FMINGS • Results of the investigation are summarized below: • Soil types encountered consist of gravelly sand and sandy gravel in the backfilled area and predominantly clays and silts under the remainder of the site, The amount of sand appears to increase towards the northwestern portion of the site. • On May 2, 1994, static water levels averaged 10.48 fbg (an average elevation of 21.0 feet above mean sea level [NGVD-1929]). The calculated ground water gradient is approximately 0.013 foot-per-foot toward the north. • No dissolved-phase TPH-G or BTEX concentrations were detected in any onsite or offsite monitoring wells. Dissolved-phase TPH-D was present only in AW-3 (210 parts per billion [ppb]). No other wells at the site have had detectable concentrations of hydrocarbons since October 1993. • No adsorbed-phase TPH-G or BTEX concentrations were detected in soil borings SB-1 through SB-5, located on the southern half of the property, or SB-11 located offsite to the east. Adsorbed-phase TPH-G and BTEX concentrations were detected in borings SB-6, SB-7, SB-8, SB-9, and SB-10 from soil samples collected from 6.5 to 16.5 fbg. Maximum TPH-G and benzene concentrations of 1,200 and 8.4 ppm respectively, were detected in soil boring SB-7 at 11.5 fbg. All detected TPH-G and BTEX concentrations were from soil samples collected below the static water table (except Boring SB-10 at 6.5 fbg). No gasoline-range hydrocarbons were detected below 16.5 fbg in any soil boring. • No adsorbed-phase TPH-D concentrations were detected in borings SB-1, and SB-2, on the southern half of the property, or SB-11, offsite to the east. Diesel range hydrocarbons were detected in borings S13-3 through SB-10 from soil samples collected below the static water table. A maximum TPH-D concentration of 6,700 ppm was detected in soil boring SB-8 at 11.5 fbg. At 16.5 fbg no TPH-D concentrations were detected in this boring. No diesel-range hydrocarbons above 3.2 ppm were detected below 16.5 fbg in any soil boring. 6.0 CONCLUSIONS Based on the results, Alton Geoscience concludes: • Adsorbed-phase hydrocarbons are characterized laterally to the east by boring SB-11, to the south by borings SB-1 and SB-3, and to the north by borings B-11 and B-12. Adsorbed-phase TPH-G and TPH-D were detected offsite to the west in boring SB-10, however, no benzene concentrations were detected in this boring. • Laboratory results for soil Borings SB-1 through SB-5 completed on the southern half or rear of the property, indicate that hydrocarbons have not impacted soil in this vicinity. . Adsorbed-phase hydrocarbons are characterized vertically beneath the site. Residual adsorbed-phase hydrocarbons are present from 11.5 to 16.5 fbg. These residual 4