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CLEARWATER ,- <br /> ROUP,- I IV C. <br /> from.MW-3:-'.Groundwater elevations and analytical results are presented on-'Table.. ` <br /> 2. Dissolved_hydrocarbon concentrations in groundwater are displayed graphically <br /> on'Figure 4. -A copy. -of the laboratory reports and chain-of-custody forms are , <br />' attached in Appendix E. <br />' 4.0 SUMMARY <br /> The results of the field activities and laboratory analyses of soil and groundwater <br /> samples collected during this phase,of investigation are discussed below: <br /> * Three two-inch diameter monitoring wells (MW-1' through MW-3) were installed; . ' : <br />' at'the site on March 31, 1995. <br /> • Sediments encountered during drilling consisted primarily of, silt, sand, and <br /> sand/silt mixtures, with occasional subsidiary clay.. An apparently .continuous . <br /> layer of sand was observed below•.more fine grained (silt) sediments. The contact <br /> between.the. silt and sand was encountered at approximately 20730 feet, bgs. The <br /> sand was observed to range from..five to 11 feet in thickness. <br /> I" Depth to'groundwater in each of the wells ranged frorri 45.87 to 47.26 feet bgs. . <br /> Groundwater=flow is,towards the north, at an approximate 'gradient of 1.71/6: <br /> TPHg, BTEX and TPHd were' detected in% soil samples collected from all the soil <br /> borings. <br /> • TPHg and-all BTEX compounds were detected in groundwater samples 'collected <br /> from all wells. The highest detected concentration of benzene was 18,000 b in <br /> • . g PP <br /> the MW-1 sample. _ <br /> 5.0 CONCLUSIONS AND RECOMMENDATIONS <br /> The,results,of analysis of'samples collected-during this phase of site investigation <br /> confirm:the presence of hydrocarbon compounds-in soil and groundwater beneath <br /> - the subject,site. Field observations and,laboratory results indicate that, in the- areas <br /> evaluated, hydrocarbon-concentrations_in soil are most:significant near 'the contact <br /> ' ,"' 'between the intermediate-depth sarid;an underlying silt unit.. <br /> Additional site characterization is necessary to delineate the extent of hydrocarbon <br /> contamination and provide information pertinent to the evaluation of feasible, _ <br /> remedial alternatives. This activity will involve the installation of additional = <br /> groundwater.monitoring wells and the completion of vadose and water bearing <br /> D-105 PSA 5 May 25, 1995 <br />