Laserfiche WebLink
Problem Assessment Report <br />for Soil and Groundwater Contamination <br />Corrigan Property (Project No W0541 00) <br />7.1 Cap and Monitoring <br />' The area of documented soil contamination, as well as the majority of the project site as a <br />whole, is covered by relatively impermeable surfaces (asphalt) Because infiltration of moisture <br />' to the subsurface is thereby significantly reduced the potential for migration (driven by <br />percolation of moisture through the contaminated soil horizon) is limited. Natural degradation <br />' of the residual hydrocarbon contamination should occur over time Periodic <br />monitonng/sampling of well MW 1 and MW2 would provide assurance that groundwater quality <br />is not being adversely affected Due to very shallow groundwater at the site and documented <br />soil contamination at the soil/water interface, it is questionable if this alternative would meet <br />' regulatory criteria for the protection of groundwater quality <br />7.2 Soil Excavation <br />Excavation of the shallow soil contamination and on-site aeration or off-site disposal to a <br />certified waste disposal facility would remove the potential source of groundwater contamination. <br />As discussed in the previous section, it is estimated approximately 250 to 300 cubic yards of <br />residual hydrocarbon contaminated soil remain in the vicinity of the former u/g diesel tank pit. <br />The excavation of contaminated material may be limited to the east due to the existing structure. <br />On-site aeration/bioremediation, if possible, would be preferred to off-site disposal because of <br />the expense and continued long term liability associated with disposal of contaminated matenal <br />at an off-site facility Confirmation soil sampling should be conducted on the walls and floor <br />of the excavation to assure successful excavation of impacted soils <br />7.3 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 />wells within the area of soil contamination A vacuum pump would be used to apply a negative <br />pressure head to drive volatile hydrocarbon constituents to the vapor wells These wells would <br />foPAR -M93 FNL 7 <br />