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6.0 REMEDIATION ALTERNATIVES <br /> 6k1 Soil Remediation Alternatives <br /> Soil remediation alternatives include cap/monitoring, excavation of impacted soil, and in-situ soil <br /> venting/vacuum extraction. A summary of each alternative is presented below <br /> 6.1.1 Cap and Monitoring <br /> IThe area of documented soil contamination, as well as the majority of the project site, is covered <br /> by relatively impermeable surfaces (asphalt and concrete) Because infiltration of moisture to <br /> the subsurface is thereby significantly reduced, the potential for migration (driven by percolation <br /> of moisture through the contaminated soil horizon) is limited Natural degradation of the <br /> residual hydrocarbon contamination should occur over time Periodic monitoring/sampling of <br /> groundwater monitoring wells would monitor whether groundwater quality is being adversely <br /> affected Due to very shallow groundwater at the site and documented soil contamination at the <br /> soil/water interface, it is doubtful that this alternative would meet regulatory criteria for the <br /> protection of groundwater quality <br /> ' 6.1.2 Soil Excavation <br /> 1 Excavation of the shallow soil contamination and off-site aeration or disposal to a certified waste <br /> disposal facility would eliminate residual soil contamination as a continuing potential source of <br /> ' groundwater contamination As discussed in the previous section, it is estimated approximately <br /> 800 to 1,125 cubic yards of residual hydrocarbon contaminated soil remain in the vicinity of the <br /> ' former tank pit Confirmation soil samples should be collected from the walls and floor of the <br /> excavation to assure successful excavation of impacted soils On-site aeration does not appear <br /> to be an option unless the process is completed in its entirety while school is not in session <br /> Off-site disposal appears to be the most feasible option for the excavated soil <br /> 6.1.3 In-Situ Soil Venting/Vacuum Extraction <br /> ' In some circumstances in-situ remediation of soils can be accomplished by installation of a soil <br /> venting/vacuum extraction system This would entail the completion of shallow vapor extraction <br /> 15008'/\R-053194 FNL 7 <br />