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• Soil types encountered consist of silty, sandy gravel in the backfilled area and . predominantly clays and silts under the remainder of the site. Sandy silts and sandy clays are present across the site from grade to between approximately 10 and 15 fbg. Underlying these units, a fine- to medium-grained sand is present in all soil borings. In the northern portion of the site, the sand appears as a distinct iithologic unit, attaining a thickness of approximately 3 feet (AW-10). Silty clay underlies the sandy zone, and persists to the total depth of the borings. Saturated soils are generally encountered at a depth of between 10 and 11 fbg. * On May 27, 1993, static water levels averaged 10.5 fbg (an average elevation of 21.0 feet above mean sea level [NGVD-1929]). The calculated ground water gradient is approximately 0.01 foot-per-foot toward the north/northeast. • No dissolved-phase TPH-G concentrations were detected in onsite or offsite monitoring wells. Dissolved-phase TPH-D was present in detectable concentrations only in AW-3 (210 parts per billion [ppb]). Dissolved benzene was detected in AW-9 and AW-12 at concentrations of 3.4 and 9.6 ppb, respectively. • Adsorbed-phase hydrocarbons were detected in Monitoring Wells AW-10, AW-11, and AW-12 at the capillary fringe. Soil samples were collected for chemical analysis at 10, 11, and 12 fbg. Maximum adsorbed-phase TPH-G, TPH-D, and benzene concentrations were 590, 3,700, and 6.6 ppm, respectively. • A review of the field descriptions of select soil samples collected from the aquifer in AW- 10, AW-11, and AW-12 indicates the material to be sand with fines, with content varying from 20 to 44 per cent by weight. Values of hydraulic conductivities (K) for these soil types range from a high of approximately 2 x 10' to less than 2 x 1W ft/min (for silty sand [Freeze and Cherry 1979]). • Aquifer testing estimated the shallow aquifer could yield approximately 2.0 gpm from AW-9. 7.0 CONCLUSIONS Based on the results of this and past investigations, Alton Geoscience concludes: • No free product is present on ground water beneath the site. • Based on the results of field activities and laboratory analyses, the lateral extent of dissolved-phase hydrocarbons in ground water is adequately characterized. Dissolved- phase hydrocarbons appear limited to the north/northwest portion of the property (in the A,-;n4 of AW-3 and AW-9), and may extend offsite under Grantline Road. The results of ground water analyses indicate that dissolved-phase hydrocarbons are not present along . the north side of Grantline Road. 7 F f