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11 Alternative 1 - Passive Remediation <br /> This alternative would involve no active remediation Naturally occurring microbes which <br /> ' degrade petroleum hydrocarbon constituents over time would be utilized to gradually reduce <br /> residual hydrocarbons in the soil Existing site wells would be destroyed under local and state <br /> ' guidelines to reduce the potential for vertical migration of contaminants Minimal capital outlay <br /> would be required for this option to be put into action Initiation would involve overdrilling the <br /> ' vapor wells and pressure grouting the boring The likelihood of future groundwater impact <br /> exists because the site is not fully paved and subsurface soil is highly permeable The shallowest <br /> water beanng zone is located approximately 25 feet below the deepest impacted soil <br /> 7.2 Alternative 2 - Soil Excavation and Off-site Disposal <br /> ' This alternative would include the excavation and disposal of petroleum hydrocarbon impacted <br /> soil from the subject site Estimated total volume of impacted soil is 900 cubic yards but the <br /> total volume of soil to be excavated would be much greater because of the depth of excavation <br /> and sloping requirements Due to the large volume of soil to be excavated, only clean soil <br /> would be stockpiled on site If possible, the impacted soil would be excavated, loaded and <br /> transported to a landfill permitted to accept the excavated soils in an ongoing process <br /> ' Excavation depth is estimated at 45 feet The extent of the petroleum hydrocarbon impacted <br /> areas that would require excavation are shown on Plate b The existing vapor and groundwater <br /> wells would be destroyed during the excavation process <br /> ' A photoionization detector would be used to screen samples during excavation to attempt to <br /> define the limits of petroleum hydrocarbon contamination Confirmation sidewall and floor <br /> ' samples would be collected from the excavation prior to excavation closure to confirm complete <br /> removal of the contamination or define any contamination left in place All soil samples would <br /> ' be analyzed for BTEX and TPHg by EPA methods 8020 and 8015, respectively <br /> 1500471REPOR'B\CAP 06%FNL 9 <br />