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landfilling), but it would not be appropriate as a separate remedial <br /> alternative for the site <br /> The two isolated areas at Site #1 containing TPH concentrations <br /> exceeding 100 mg/kg currently lies immediately adjacent to the <br /> southwest wall of the warehouse building and an isolated location <br /> within the former excavation area Excavation of the hydrocarbon- <br /> impacted soils in the vicinity of Former Tank Site #1 would require <br /> shoring the warehouse building at the site and performing dewatering <br /> activities to prevent soil slumping during removal These activities <br /> would not present a practical alternative for the site, as the extent of <br /> TPH-impacted soil is limited Accordingly, excavation and related <br /> treatment alternatives were eliminated as alternatives for Site #1 <br />' The majority of the area at Site #2 containing TPH concentrations <br /> exceeding 100 mg/kg currently underlies the warehouse building <br /> (Figure 5-1) Excavation of the hydrocarbon-impacted soils in the <br /> vicinity of Former Tank Site #2 would require major structural <br /> changes to and/or demolition of the warehouse building at the site <br /> Demolition of the building would not be a practical alternative for the <br /> site Accordingly, excavation and related treatment alternatives were <br /> eliminated as alternatives for Site #2 <br /> Soil Venting Vapor Extraction <br />' This alternative involves in-place passive or active removal of soil <br /> vapors from unsaturated soils Passive soil venting would consist of <br />' installing perforated pipes into the affected soils to allow the volatile <br /> hydrocarbon constituents to vent; however, the specific site soils <br /> would probably not respond quickly enough to passive treatment due <br />' to their low permeability. In vapor extraction, a vacuum is applied to <br /> the perforated pipes to remove hydrocarbon-laden vapors from the soil <br /> pores The vapors are then either treated (via an air stripper or <br /> granular activated carbon unit) or released directly to the atmosphere <br />' (with an approved air permit) <br /> This soil treatment technology is implementable since it only requires <br /> the use of conventional drilling equipment and a vapor treatment <br /> unit Vapor extraction has also been proven to be effective at <br /> numerous sites and over a wide range of operating conditions, <br /> however, vapor extraction is only effective for affected soils above the <br /> water table Therefore, this alternative would only be applicable to <br /> hydrocarbon-impacted soils at Former Tank Site #2 because TPH- <br /> impacted soils at Former Tank Site 01 are located below the water table <br />' 6-2 <br />