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C C C C c C a meaningful estimate of the mass of hydrocarbons removed during excavation. The maximum concentration detected in samples collected prior to excavation was 3,140 ppm TPHG. Field observations made by Ground Zero and PHS/EHD personnel of soil samples collected during recent subsurface investigations indicate that the excavation successfully removed all impacted J soil in the unsaturated zone. In addition, no contamination was noted in saturated soils above 20 feet bgs or below 35 feet bgs in boring SB8, located in the former tank excavation. The shallow groundwater beneath the site has been moderately impacted by petroleum hydrocarbons. The estimated extent of dissolved hydrocarbons in the groundwater is shown on Figures 3 and 4. Based upon the relatively impermeable soil and the evidence of intrinsic bioremediation occurring beneath the site, passive remediation should be effective in reducing dissolved concentrations in groundwater. 5.3 Site Specific Information Summary o No municipal, industrial or agricultural wells are known to exist within 2,000 feet of the project site. The nearest supply well to the site is located at 2059 Navy Drive, near Tillie Lewis Drive, approximately 2,500 feet northwest of the site (Figure 5). ;t o Figures 1 through 4 depict the site location and nearby surface waters (Figure 1), the site to scale and the location of the soil excavation (Figure 2), estimated extent of i groundwater contamination (Figure 3) and a stratigraphic cross section of the subsurface (Figure 4). O Groundwater was initially encountered during drilling in 1989/1990 at approximately 25 feet bgs. During drilling in June 1996, groundwater was initially encountered at approximately 15 feet bgs and subsequently stabilized in the monitoring wells at approximately 12.8 feet bgs. groundzeVanuioklosure