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Geologfcal Ttclsirfcs lxc Page 12 Site Conceptual Model Report Marci Property Project No 701 2 August 23,2004 and theP lan includes numerical Water Quality Objectives (WQO) The WQO for the site's COC and their current maximum levels in groundwater are included in the table below ' COC June 7, 2004 WQO [max. conc. u )] (RW CB, Aril 1, 2004) ' Diesel 7310 56 Gasoline ND<50 5 X07 Benzene 0.7 0 15 1L Toluene ND<0 3 42 ELh 1 benzene ND<0 3 29 ' Xylenes 9.8 17 The diesel and benzene concentrations exceed the RWQCB-CVR water quality objectives It ' is likely that the free product discovered in boring MW-7 soils will continue to contribute to contaminant levels above the WQO if not addressed 4.2 Conclusions Based on our interpretation of the data collected over the course of this subsurface investigation, GTI has reached several conclusions These conclusions are based on the premise that the data considered, although incomplete, are representative of actual site conditions We acknowledge that there may be undiscovered conditions, which would upon their consideration,change our interpretation and thus our conclusions Geological Technics Inc makes the following conclusions ® The geology of the site consists primarily of alternating layers, lenses and interstratified beds of clays, silts and sands Units containing gravels are less ' frequent As discussed above, we have an incomplete understanding of the geologic parameters of this site since the standard practice for drilling and soil sampling lends to an incomplete vertical profile record ' 4 Figure 3 Geologic Cross-Section A-A' illustrates the subsurface from the southwest to northeast sections of the subject area The interpretation incorporates sub-classes sucli as gravelly clay and silty clay which are consolidated-into the general category of - ' clays There is little correlation in lithologic units between borings Boring MW-3 (logged by Wm Hunter & Associates) contains significantly more clay than the other boreholes ' • Figure 5 Geologic Cross-Section B-B' illustrates the subsurface from the northwest to southeast sections of the subject area There is little correlation in lithologic units between borings as in Cross-Section A — A' Boring MW-2 (logged by Win Hunter & Associates) contains significantly more clay than the other boreholes Together, with the MW-3 data, this suggests that contamination would be less likely to migrate F eastward across the site