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LEEDSHILL HERKENHOFF, INC <br /> RECOMMENDATIONS <br /> From LH's preliminary investigation, it appears that petroleum hydrocarbon <br /> constituents exist in the soil in the northwest corner of the site further <br /> investigation of this area is warranted. Therefore, LH recommends that two or <br /> three soil borings be installed in the northwest corner of the site to determine <br /> the extent of the contaminated soil for future remediation. <br /> Groundwater appears to flow in an easterly direction at a gradient of <br /> 0.005 ft/ft. Monitoring wells located downgradient at the site, MW2 and MWS, <br /> contain high levels of dissolved petroleum hydrocarbons. This suggests that <br /> contaminated groundwater may be moving offsite. Monitoring wells MW1, MW3, and <br /> MW4 also show detectable concentrations of BTX&E, suggesting possible off-site <br /> sources. Information regarding the upgradient Texaco service station located <br /> approximately 15 feet to the west of the project site should be collected and <br /> evaluated as a potential source. <br /> In order to address the offsite, downgradlent lateral extent of the suspected <br /> contaminant plume, LH recommends installation of an off-site monitoring well <br /> east of the site. <br /> An aquifer test from one of the existing 4-inch monitoring wells is also <br /> recommended to determine aquifer characteristics for future remediation <br /> As for the current status of the site, LH recommends that the soil stockpile <br /> and non-hazardous soil contained in drums be used as backfill material in the <br /> currently open excavation. The excavation should be backfilled to grade, <br /> compacted, and repaved to minimize the physical safety hazards associated with <br /> this open excavation. <br /> 9832-12.rpt/dk3 <br /> -27- <br />