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Mr. Mike So t'oodward•Clyde Consultants <br /> LOF Glass <br /> April 17, 1986 <br /> Page 3 <br /> Based on our current understanding of the site conditions and assuming no <br /> significant problems have been encountered with the current system we <br /> recommend that the existing recovery system continue to be operated in <br /> its present form with a few modifications. A 12 inch diameter PVC well <br /> should be set in the open pit at a depth of 20 ft to accommodate a two <br /> pump recovery system and allow for greater drawdown if they are deemed <br /> necessary at some point in the future. The existing double diaphram <br /> pumps should be used in this well and wells MW-9 and MW-10 to both <br /> depress the water table and recover the oil. Pump effluent should <br /> continue to be processed through the oil/water separator and waste water <br /> treatment plant. A control can be incorporated into the system to <br /> activate the pumps periodically depending on the recharge rates to the <br /> wells. This will reduce air consumption and pump maintenance if they are <br /> presently a problem. <br /> The amount of water table drawdown should be the minimum required to <br /> adequately influence the entire estimated area of contamination. The <br /> distance from well MW-9 and the pit well to the assumed outermost <br /> perimeter of the contaminated area should be calculated. This distance <br /> will dictate the minimum radius of the cone of depression created by well <br /> drawdown. The size of the cone should be determined by pumping from one <br /> well at a time and observing the drawdown in adjacent wells. The <br /> drawdown can be adjusted until the optimum cone size is reached. The <br /> pump intakes should be adjusted periodically to maintain the same amount <br /> of drawdown relative to seasonal fluctuations. Pumping from well MW-10 <br /> may not be required as the cones from MW-9 and the pit well may overlap <br /> and cover the entire area. Although it is not critical, the pump intake <br /> should not extend below the lower extent of the natural range of <br /> fluctuations to avoid contaminating previously clean sediments. <br /> It should be noted that these recommendations are preliminary and may be <br /> revised after a review of recovery system performance and monitoring well <br /> data. Should system performance or maintenance requirements prove to be <br /> unsatisfactory, a single downhole submersible pump or two-pump recovery <br /> system may be required. Well and recovery data may indicate that only <br /> one or two of the wells will require a recovery system or that a larger <br /> drawdown than what is currently anticipated will be necessary. <br /> If you have any questions or comments, please feel free to contact me. <br /> Sincerely, ���� <br /> A�i�i __ � <br /> Martin Cramer <br /> Project Scientist <br /> MC:rb <br /> 2414c* <br />