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1 GERAGHTY & MILLER, INC $ <br /> ® source removal by excavation followed by groundwater monitoring and sampling, <br /> ® biosparging, <br /> ' ® SVE, and <br /> G blosparging with SVE <br /> Geraghty & Miller generally concurs that these were the most appropriate options to <br /> consider GTT proposed bnosparging only, because of its ability to remediate the remaining <br /> ' source of groundwater contamination in-situ while causing the least impact to service station <br /> business Geraghty & Miller implemented a more technically capable and cost-effective <br /> ' combination of SVE and biosparging to enhance source removal in the vadose zone and <br /> address groundwater contamination <br /> ' The influence of the installed remediation system corresponds, in areal extent, to the <br /> ' petroleum hydrocarbons found in soil, as shown in Figure 3 The number and location of <br /> remediation wells was based on Geraghty &Miller's previous experience at sites with similar <br /> litholognc conditions <br /> The combination of SVE and biosparging is an effective technique to remediate <br /> hydrocarbon-impacted soils and groundwater simultaneously SVE is effective for vadose- <br /> zone soil remediation, but is limited in its efficiency for remediating beneath the water table <br /> ' This limitation is being addressed by the use of biosparging in the saturated zone. Biospargtng <br /> involves the infection of air into the groundwater This air removes a portion of the hydro- <br /> carbons in the water by volatilization and another (typically larger) portion through enhanced <br /> biodegradation Another remediation benefit is the enhanced air-flow pattern near the ground- <br /> water surface, where elevated concentrations of hydrocarbons are generally encountered in the <br /> ' smear zone During biosparging, aur is forced up through the groundwater into and through <br /> the smear zone <br />' ENHANCED BIOREMEDIATION <br /> ' A variety of indigenous organisms that live in the subsurface can convert petroleum <br /> hydrocarbons to less toxic byproducts In aerobic respiration, microbes transform petroleum <br /> ' hydrocarbons to carbon dioxide by transfemng electrons from the contaminant (oxidizing it) to <br /> oxygen or to a less-favored electron acceptor. DO is the most thermodynamically-favored <br /> electron acceptor used in the biodegradation of petroleum hydrocarbons, which are readily <br /> biodegradable under aerobic conditions Ideally, aerobic biodegradation of petroleum <br />' <br /> Project No RC0309 010 <br />