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' T&T Trucking Subsurface Investigation Results and Site Conceptual Model IPage 4-9 • The fence diagram shown in Figure 4-9 is a more dimensional interpretation of the SCM created by connecting both cross sections in a spatially accurate position At a glance, one can see the lateral extent of contamination extends more to the southwest than any other direction and most of the layers are somewhat continuous ' As shown on Figure 4-7� is present resent in soil from 25- to 65-ft bgs and in water from 70- to � 108-ft bgs in the source area MtBE has consistently been detected in samples from monitoring ' wells MW-1, MW-3, and MW-4 as described in the Second Quarter 2003 Groundwater Monitoring Report Groundwater samples from Well MW-2 have not contained MtBE concentrations above the reporting limit since May, 2001 Lateral delineation of MtBE in groundwater appears to have been completed as shown by ' concentrations of MtBE below method detection limits in all of the perimeter CPT locations (CPT-2 through CPT-7) in Figure 4-8 MtBE concentrations decrease with depth in the water column in the source area, however vertical delineation of MtBE in groundwater has not been ' completed in the source area below 108-ft bgs The deepest Hydropunch® sample completed is 108-ft bgs Because MtBE concentrations were detected in groundwater at 108-ft bgs, below the clay and silt layer, it is presumed that the layer has some permeability or the layer is inconsistent in depth ' in the area of the former UST Lateral delineation of TPH-g in soil and groundwater appears complete to the north, east, and south of the former UST area, but not to the west,in the area of CPT-2 Low concentrations of TPH-g in groundwater were detected in the first encountered water (73-ft bgs) at CPT-2 which is located west of CPT-1 and the tire shop Concentrations of TPH-g in groundwater were not detected above reporting levels in samples collected from 100 and 112-ft bgs in CPT-2 TPH-g concentrations were not detected in any of the water samples from CPT-3 through CPT-7 ' Groundwater monitoring results have indicated TPH-g concentrations consistently detected in groundwater samples from monitoring well MW-3 Groundwater samples from monitoring well MW-1 have had elevated reporting limits for TPH-g due to high concentrations of MtBE, and MW-4 has either had concentrations of TPH-g above the detection limit or elevated reporting limits due to high concentrations of MtBE ' P\23000\23954 1`1 trucking\CP'I Summary Report\]]NAL f&T fruckmg DOC