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r <br /> Extraction Well Memorandum -4- 17 December 1991 <br /> DDRW, Sharpe Site <br /> Ready-mix cement may not present a problem unless the cement (from the <br /> truck) is not tremmied into the annular space and if the cement remains in <br /> the truck too long, requiring the addition of retarders. <br /> Page 3-5. The Work Plan indicates that electric logging will be performed on the <br /> boreholes of each of the extraction wells prior to completion of the <br /> extraction well . The electric logs will be used along with the Iithologic <br /> logs to determine the screen interval and length. We commend Sharpe for <br /> using electric logging for this purpose. <br /> Page 3-7. The Work Plan states that water removed from the extraction wells during <br /> development will be contained and treated in the South Balloon Area. It <br /> is unclear why the development water will be treated in the South Balloon <br /> Area when the extraction wells are being installed and there is a <br /> treatment plant in the North Balloon Area. <br /> Page 3-8. The Plan states that pump tests will be performed on each of the <br /> extraction wells once installed. Sharpe may want to consider modifying <br /> the pump tests to perform a "mini" aquifer test on some of the extraction <br /> wells if there is presently insufficient hydraulic information on a <br /> particular zone in a particular area. <br /> Page 3-16. Once the extraction wells are developed, the well samples will be analyzed <br /> using Methods 601 and 602 (Purgeable Hydrocarbons and Purgeable Aromatics, <br /> respectively) . If the results of the first sampling round indicate that <br /> Purgeable Aromatics are not present and that these constituents have <br /> historically not been present in the surrounding monitor wells, then <br /> analyses using Method 602 are no longer necessary and should be <br /> discontinued. This recommendation is also applies to all of the monitor <br /> wells at the site. <br /> Additionally, Sharpe should consider the use of the 500 series methods for <br /> analysis, rather than the 600 series methods for VOCs. The 500 series <br /> methods generally have lower detection limits than the 600 series. <br /> CKW:cw <br />