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I <br /> a Alternative 1 Passive Remediation <br /> o Alternative 2 Soil Excavation and Offsite Disposal <br /> o Alternative 3 Soil Vapor Extraction and Groundwater <br /> Monitoring <br /> o Alternative 4 Soil Vapor Extraction, Air Sparging, and <br /> Groundwater Monitoring <br /> o Alternative 5 Groundwater Extraction and Treatment <br /> The general response alternatives for the site considered above are discussed below <br /> ' 32 1 Alternative 1 - Passive Remediation <br /> i This alternative would involve no active remediation of gasoline hydrocarbons in soil or <br /> groundwater beneath the site Naturally occurring microbes which degrade gasoline <br /> r hydrocarbons over time would be utilized to gradually reduce residual gasoline hydrocarbons <br /> ' in soil and groundwater Groundwater contaminants would be monitored on a regular basis <br /> via the existing site wells to monitor the migration of contaminants Minimal capital outlay <br /> would be required to implement this option The likelihood of continuing groundwater <br /> impact exists because the subsurface soil is sufficiently permeable to enable vertical <br /> migration of gasoline hydrocarbons into the groundwater bearing zone located immediately i <br /> below the deepest impacted soil at approximately 60 feet bgs <br /> 3.22 Alternative 2 - Soil Excavation and Offsite Disposal <br /> This alternative would include the excavation and disposal of gasoline hydrocarbon impacted <br /> ' soil from the subject site Estimated total volume of impacted soil is 2,670 cubicY ards but <br /> the total volume of soil to be excavated would be much greater because of the depth of <br /> 1 excavation and sloping requirements Shoring of the excavation sidewalls would also be <br /> required Due to the large volume of soil to be excavated, only clean soil would be <br /> stockpiled on site If possible, the impacted soil would be excavated, loaded and transported <br /> to a landfill permitted to accept the excavated soils in an ongoing process Excavation depth <br /> is estimated at 60 feet The lateral extent of the gasoline hydrocarbon impacted areas that <br /> would require excavation are shown on Figure 8 All vapor and several groundwater wells <br /> 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 samples <br /> 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 <br /> would be analyzed for BTEX and TPHg by EPA methods 8020 and 8015, respectively <br /> groundzelrGATap 10 <br />