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Work Plan for Refined Plume Definition and Management ofFloatin Product- <br /> 7500 W I1 th St., Tracy, C.4. Page 74 <br /> ,. demolition and disposal, site restoration <br /> and engineering report.) <br /> Total Estimated System Closure Cost $15,450 <br /> 9.4.3.10 Advantages and Disadvantages <br /> The key advantages and disadvantages of skimming floating product from extraction wells <br /> using pumps and on-site staging of recovered product prior to disposal compared to the <br /> alternate technologies considered in this work plan are summarized below. <br /> Advantages: <br /> None Apparent <br /> Disadvantages: <br /> Very High Capital Cost <br /> • Very High Operating Cost <br /> • High Closure Cost <br /> Mir • Extraction well diameters are at least one order of magnitude less than the <br /> site-specific minimum elementary volume; thus wells will not reliably <br /> intersect inflow of LNAPL from permeable zones at all scales and from a <br /> wide area. <br /> • By design, skimmer pumps generate only minimal drawdown of water <br /> table in wells, thus the effective zone of influence induced around the <br /> f wells from which LNAPL is extracted is likely to be very small. <br /> 1� • There is no assurance that full cut-off of pathways for down-gradient <br /> migration of LNAPL can be achieved. <br /> • Subsurface conditions and inflow of floating product not observable in <br /> wells. <br /> • System will likely require at least weekly monitoring visits to make sure it <br /> is not malfunctioning <br /> _ • Fixed pre-determination of well locations does not permit (except to a <br /> minimal degree) application of the Observational Method to situate <br /> LNAPL extraction point at optimal locations based on actual subsurface <br /> :. conditions. <br /> sic <br />