Laserfiche WebLink
1 <br /> are typically introduced into vadose zone soils through a network of tightly-spaced infection points <br /> An extensive pilot study would be required to establish the proper microorganisms to introduce and <br /> their quantity Due to the fine-grained nature of the vadose zone soils at the Site, effective and <br /> uniform application of nutrients would be difficult to achieve in shallow soils Groundwater <br /> remediation would be required to recover solubilized VOCs that are carred into groundwater <br /> Due to the expense and time necessary to conduct a pilot study and the necessity of groundwater <br /> extraction in mtu bioremediation of shallow soils does not appear to be suited for this facility and will <br /> not be retained for further consideration <br /> 6 14 OPTION IV- Excavation With Off-Site Disposal/Treatment <br />' Hydrocarbon impacted soil remains beneath the new tanks at depths ranging from 24 to 75 feet bgs <br /> Under Option IV, petroleum hydrocarbon-affected soil would be excavated to below the water table <br />' and removed from the Site for disposal at a licensed treatment/recycling facility Because of the <br /> configurations of the hydrocarbon plume in soil, Option IV activities would require the excavation <br /> ofUSTs, dispenser islands and piping, city sidewalks and streets, removal and disruption of utilities <br /> that service the Site, installation of shoring, disruption of access to the Site, and the release of VOCs <br /> into the air during excavation activities An additional drawback of this remedial method is that <br /> groundwater Ievels may continue to increase after excavation remediation has been completed, <br />' transporting petroleum hydrocarbon-laden groundwater into clean fill soil and re-contaminating the <br /> area <br /> 6.2 Groundwater Remediation <br /> 6 2 1 OPTION I - Passive Groundwater Remediation-No Action <br /> Passive groundwater remediation relies upon the principle that petroleum hydrocarbon compounds <br /> will naturally degrade or attenuate over time Such degradation and/or attenuation can be attributed <br /> in part to metabolic and co-metabolic processes occurring between indigenous microorganisms found <br /> in soil and the petroleum hydrocarbon compounds of concern Under proper circumstances, passive <br /> remediation can be an appropriate choice Sites with groundwater having adequate populations of <br /> petroleum hydrocarbon-degrading bacteria, nutrients, and oxygen levels may be a good choice for <br /> this alternative Additionally, sites in areas which pose httle risk or threat for potential human contact <br /> may also be amenable to this alternative This alternative is not viable for the Site because petroleum <br /> hydrocarbon concentrations in groundwater generally exceed allowable levels <br />' 6 2_2 OPTION II - Soil Vapor Extraction and Groundwater Pump and Treat <br /> In situ soil vapor extraction and groundwater pump and treat is a recognized and effective technology <br />' for the treatment of subsurface soil affected by volatile compounds The process facilitates the <br /> removal of hydrocarbons by continually circulating air through the soil, enhancing evaporation and <br /> desorption of volatile from unsaturated soils in the vapor stream Soil vapor extraction will operate <br /> A11528J1 ASA 16 <br /> 1 <br />