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5.2 Technology Identification and Screening <br /> The general response actions necessary to achieve the remedial objectives are <br /> 1 Identify the extent of the dissolved-petroleum hydrocarbon plume <br /> 2 Dissolved-petroleum hydrocarbon plume management <br /> 3 Reduce the mass of petroleum hydrocarbons identified in groundwater and <br /> soil <br /> The general response actions are used to focus the transition from remedial objectives to tech- <br /> nological applications Each response action addresses one or more of the remedial objec- <br /> tives In addition, Response Action 1 addresses the need for plume delineation before the <br /> remedial objectives can be fully realized <br /> 5.2.1 Technology Screening <br /> To identify applicable technologies, key site conditions must be considered These conditions <br /> were generally outlined as part of the site conceptual model, and are further detailed below as <br /> remediation design considerations <br /> Remediation Design Considerations <br /> • Rough estimates regarding the hydrocarbon mass in groundwater, soil, and <br /> the capillary fiinge showed that most of the hydrocarbon mass is located <br /> beneath the site in isolated soil columns located between 15 and 45 feet <br /> bgs For the most part, impact appears to reside in soils of relatively low <br /> permeability <br /> • Two years of SVE were completed, significantly changing the soil chemis- <br /> try quality Approximately 12,000 pounds of TPH-g were removed, and <br /> influence appeared to cover the affected area But, based on data provided <br /> above, a lirmted soil volume is still impacted with hydrocarbons It appears <br /> variations in soil permeability to air flow, competing pressure gradients, <br /> extraction well screen placement (relatively recent dewatering has exposed <br /> volumes once submerged) and the chemical characteristics of the target <br /> compounds controlled the degree and pace of remediation <br /> • If volatilization (equilibrium) is the mechanism by which vapor-phase <br /> hydrocarbons are generated, it follows that the toss of gasoline components <br /> from the soil began with the most volatile (low molecular weight) gasohne <br /> compounds and moved on toward the least volatile (high molecular weight <br /> 3201337BI1918REV 19 August 31, 1995 <br />