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XtD r Monitoring wells MW-8 and MW-9 were installed on December 12, 1990 No soil samples were collected from these borings All soil PID measurements were reported as non-detected Monitoring wells MW 10, MW-11 and MW-12 were installed on July 11, 1996 and monitoring I well MW-3A was installed on July 12, 1996 No hydrocarbon constituents were detected in any of the soil samples taken from MW-10 and MW-11, except for the sample collected from the 65 to 66 5 foot interval m MW-10 Concentrations of benzene, toluene, total xylenes, and TPH-G ' were detected No soil samples were collected from monitoring well MW-12 All soil PID measurements were reported as non-detected On May 24 through June 2, 1999 a site investigation was conducted that included the advancement of seven soil borings (SB-6, SB-7, SB-8, SB-13D, MW-13, MW-13A and MW- 13B) and the installation of three monitor wells (MW-13, MW-13A and MW-13B) Concentrations of benzene, toluene, and total xylenes were detected in a soil sample from soil boring SB-6 at a depth of 41 5 feet below ground level Concentrations of BTEX, TPH-G and MTBE were detected in a soil sample from soil boring SB-13D In addition, two soil samples Ifrom borings SB-13D and MW-13A were submitted for physicochenucal and microbiological analyses The samples submitted for analysis revealed very low viable recoveries for I • heterotroptuc and selective microorganisms at the dilutions tested The results suggested the possibility that some level of biotoxicity existed at the site Soil boring logs and monitor well construction details are provided in Appendix A Two Cross Sections (Figure 3) were created to show the soil stratigraphy across the site Cross Section A-A' (Figure 4) extends from monitoring well MW-6 (north) to MW-9 (south) and includes wells screened in the shallow and deep aquifers Cross Section B-B' (Figure 5) extends from monitoring well MW-7 (southwest) to MW-1 (northeast) and includes wells screened in the shallow and deep aquifers In general, shallow subsurface soil at the site consists of interbedded units of fine-grained(silt) deposits and coarse-grained (sand) deposits Based on the soil boring logs, relatively fine-grained soil consisting of silt and clay was encountered from surface to approximately 60 feet bgs These fine-grained soils appeared to be underlain prmiardy by deposits ' consisting of clayey to silty sand and sand to a depth of approximately 116 feet bgs A stiff silt layer was encountered from about 116 to 118 feet bgs The silt layer was underlain by silty sand and sand ' Soil analytical data are summarized in Table 1 A Soil Boring Location Map presented as Figure 6 shows the location of each boring, and summarizes the analytical results ' Results of the soil and groundwater sampling conducted during the assessment portion of the project indicate that the horizontal extent of the hydrocarbon impact from the UST release has I • 3 I