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nor Refined Plume Definition and Management of Floating Product-7500 W 11th St., Tracy, CA. Page 58 <br /> Work Pla f f ./• <br /> 9.4.1.10 Advantages and Disadvantages <br /> The key advantages and disadvantages Technology A - Cut-off Trench and High-Volume <br /> Pumping of LNAPL- are summarized below. <br /> Advantages: <br /> • Moderate Capital Cost <br /> • Zero Operating Cost <br /> • Lowest System Closure Cost <br /> • Requires no construction on private property. <br /> mi <br /> Fully cuts off pathway for down-gradientgration of LNAPL <br /> Rapidly removes 7,000 gallons of LNAPL and contaminated groundwater <br /> from the subsurface. (Time from authorization to proceed is estimated to <br /> be 60 days.) <br /> • ,Subsurface conditions and inflow of floating product easily observed in <br /> open trench. <br /> • Length and location of cut-off trench readily modified in the field to <br /> accommodate actual conditions observed. <br /> • Size of cut-off trench is commensurate with minimum elementary volume <br /> and thus will permit rapid inflow of LNAPL into trench from permeable <br /> zones at all scales and from a wide area. <br /> • LNAPL extraction procedure generates large drawdown of water table that <br /> induces rapid flow from wide area of the surrounding subsurface. <br /> Removes a significant volume of soil contaminated by high concentrations <br /> of analytes of concern from the subsurface and eliminates that mass as an <br /> ongoing source of contamination to groundwater due to desorbtion of <br /> petroleum hydrocarbons. <br /> • Conforms to USEPA recommendations for LNAPL remediation <br /> • Provides for optional cost-effective future removal of very large quantities <br /> of contaminated groundwater. <br /> J� <br /> sic <br />