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Working To Restore Nature 12 to 20 feet to 30 feet below grade, clay from approximately 30 feet to 50 feet below grade, and clayey sand to well graded sand from approximately 50 feet to 70 feet below grade, the maximum depth explored. ' 2 Site Hydrology Groundwater beneath the site was encountered at approximately 49 feet below grade during the ' initial subsurface investigation in September 1987. The water table subsequently fell to as low as 59 feet below grade in September 1992 The water table currently lies at approximately 48 feet below grade. Groundwater beneath the site has historically been as high as 35 feet below grade in 1986. Groundwater beneath the site generally flows to the southeast with an average ' gradient of approximately 20 feet per mile. The groundwater gradient calculated from data collected on April 29, 1994 is depicted on Figure 5 Residual Hydrocarbons in Soil Analytical results of soil samples collected during subsurface investigations indicated gasoline hydrocarbon impacted soil was present in the vicinity of the former underground fuel storage tanks and fuel dispensers from approximately five feet below grade to the water table (at least 55 feet below grade). Subsequent excavation activities removed impacted soils to a depth of approximately 35 to 40 ' feet below grade, the maximum practical depth for excavation. Laboratory analyses of confirmation soil samples collected from the excavation indicated that soil contaminants were ' removed laterally, but impacted sods remained in the interval from approximately 35 feet below grade to the water table (currently 48 feet below grade). This interval is within the zone of ' historical high groundwater and consists predominantly of fine grained soils such as clays with some silts and clayey sand. The estimated lateral extent of soil impaction at depth is shown on Figure 6 I-5M8\ EPOM\C"-07%nig 13