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As in previous site investigations, sods were found to consist of fine to medium sands to a depth of approximately 15 feet This strata was underlain by clay Because previous investigations indicated that the clay unit may be acting as an aquitard, all Geoprobe points were discontinued at a depth of 15 feet to 16 feet below ground surface to prevent possible impacts to groundwater Figure 2 in the attached report includes Geoprobe point locations and Appendix A contains sod boring logs Samples collected from each probe location at depths of 4 5 - 5 feet bgs, 9 5 - 10 feet bgs, and 14 5 - 15 feet bgs were analyzed for TPH-g and benzene, toluene, ethylbenzene, and xylenes (BTEX) Additionally, samples collected from the bottom of each Geoprobe location were analyzed for total organic carbon (TOC) Samples collected from GP-3 were also analyzed for gasoline-utilizing bacteria. BTEX-utilizing bacteria, and total heterotrophic bacteria (THS) to confirm that intrinsic bioremediation is occurring Analyses identified low concentrations of hydrocarbons in the sod samples collected from GP- 1 at 9 5 - 10 feet bgs (116 ppm gasoline, 1 23 ppm ethylbenzene, and 6 71 ppm xylenes), GP-1 at 14 5 - 15 feet bgs (159 ppm gasoline, 0 282 ppm ethylbenzene, and 1 08 ppm xylenes), GP-2 at 9 5 - 10 feet bgs (77 9 ppm gasoline and 0 246 ppm xylenes), and GP-2 at 14 5 - 15 feet bgs (242 ppm gasoline, 0 341 ppm ethylbenzene, and 1 60 ppm xylenes) None of the other samples contained detectable concentrations of hydrocarbons Samples analyzed for TOC were found to contain concentrations ranging from 170 ppm to 2,000 ppm Following 20 days of incubation, bacterial counts for the samples collected from GP-3 ranged from 3 5 X 106 to 4 6 X 107 colony forming units per gram of soil for gasoline-utilizing bacteria, 4 1 X 106 to 4 7 X 107 colony forming units per gram of soil for THB, and 3 4 X 106 to 5 3 X 106 colony forming units per gram of sod for BTEX-utilizing bacteria Analytical results are summarized on Tables 1 and 2 of the attached report and laboratory reports are contained in Appendices Band C It is Time's understanding, that the PHS/EHD may wish to do some soil transport modeling to determine if the remaining hydrocarbons may impact groundwater beneath the site Accordingly, samples collected from each distinct soil strata in GP-1 (1 5 feet bgs (finer-grained sand), 12 feet bgs (coarser-grained sand), and 15 5 feet bgs (clay)) were analyzed for air permeability, total porosity, coarse grain size analysis, bulk density, and moisture content The results of theses analyses are included in Appendix C of SECOR's report Conclusions Analyses suggest that only minor concentrations of hydrocarbons remain in very limited areas beneath the subject site When compared to concentrations observed during previous investigations, it appears as though there has been a general decrease in hydrocarbon concentrations remaining in soils Additionally, plate counts suggest that sufficient populations of hydrocarbon-utilizing bacteria and total heterotrophic bacteria are present in the site's soils to support intrinsic boattenuation of the sod impacts Future Site Activities Time requests that the PHS/EHD consider site closure based on the following 1 The extent of soil impacts at the subject site is limited and well defined, and concentrations observed during the Geoprobe survey are generally lower than those observed in samples collected from similar areas during previous site investigations 2 Benzene was not present in any of the soil samples collected during the Geoprobe investigation I 3 Sufficient bacterial populations exist in the site's soils to biodegrade the remaining hydrocarbons 4 The potential for vertical migration of the remaining hydrocarbons is limited, as the site is covered • with asphalt and a lens of clay is present over the top of the first-encountered groundwater These site conditions also limit the potential for exposure to the impacted soils