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ASSOC! rrVV11 I A 7 E S INC consisted of well graded sand and poorly graded sand Soil from depths between 31 and 35 feet bgs to approximately 36 5 feet bgs, the maximum depth explored, consisted of lean clay and/or ' elastic silt with sand Soil in boring MW2 consisted of poor to well graded sand with varying amounts of silt from the ' surface to 35 feet bgs Soil from depths between 35 feet bgs and 38 feet bgs consisted of elastic silt Soil from depths between 38 feet bgs and 39 feet bgs consisted of silt with gravel Soils ' from depths between 39 feet bgs and 40 feet bgs consisted if silt Soil from depths between 40 feet bgs and 45 feet bgs, the maximum depth explored, consisted of silt with sand Soil boring/well construction logs are contained in Appendix E A cross section depicting the site stratigraphy was created and the location of the cross section is shown on Figure 5 The cross section is shown on Figure 6 1 5.1.2 Petroleum Hydrocarbons in Soil ' A review of historical soil analytical data and field measurements indicate TPHd impacted soils are generally present at the highest concentrations in borings MW2 and SB8 TPHd was generally detected at depths ranging from approximately 19 to 25 feet bgs TPHd was not detected in soil samples collected from borings MW1, MW3, MW4, and MW5 with the exception of trace amount of TPHd collected from the capillary fringe in MWI and MW3 As a result, the lateral extent of residual TPHd impacted soils appears to be limited to the area dust ' southeast of the site's former UST locations as shown on Figure 7 A review of historical soil analytical data and field measurements indicate TPHg impacted soils are generally present at the highest concentrations in borings MW2, S136, and SBS TPHg was generally detected at depths ranging from approximately 19 to 25 feet bgs TPHg was not detected in soil samples collected from borings MWI, MW3, MW4, MW5, S133, SB4, SB5, SB7, SB8, S1310, and SBI I As a result, the lateral extent of residual TPHd impacted soils appears to be limited to the area dust south-southeast of the site's former UST locations as shown 1 on Figure 8 5.13 Mass Balance Calculations - Soil ' Using the analytical results from the subsurface investigations presented in Table 1, ATC estimated the lateral extent of TPHd and TPHg concentrations in the unsaturated zone beneath ' the site as depicted on Figures 7 and 8, respectively The isoconcentration shown on Figure 7 was then used by ATC to perform mass balance calculations to estimate the mass of TPHd impacted soil The total mass of TPHd remaining in the soil is estimated to be approximately ' 580 pounds or 263 kilograms The isoconcentration shown on Figure 8 was used by ATC to perform mass balance calculations to estimate the mass of TPHg impacted soil The total mass of TPHg remaining in the soil is estimated to be approximately 386 pounds of 175 kilograms Mass balance calculations are included in Appendix F w \I3099Veportslclosure doc 6