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For each month from 3uly through and including March (A-72 ]ow flow months), <br />54.6 pounds of zinc per day will be subtracted from the actual load at A-72. For <br />each month from April through and including June (high flow months), 63.7 <br />pounds of zinc per day will be subtracted from the actual load at A-72. This <br />represents 70% of the load contributed by the Koehler Tunnel estimated by the <br />Animas River Stakeholders Group (78 pounds per day during low flow months, <br />and 91 pounds per day during high flow months)2. Subtraction of these pounds <br />per day represents the predicted effect of plugging the Koehler Tmmel. <br />For each month, 12.9 pounds per day will be added to the actual load at A-72. <br />This represents 30 % of the median load of the American Tunnel (after placement <br />of the 2"d portal plug). Final plugging is estimated to result in a 70% reduction in <br />loading. This amount is added to the A-721oad since the entire load is now being <br />removed by the American Tunnel Treatment Plant <br />for each month, 36.0 pounds per day will be added to the actual load at A-72 . <br />This represents 30% of the median load of the Mogul Mine (from August 2000 to <br />present). Final plugging is estimated to result in a 70% reduction in loading. This <br />is added to the A-72 load since the entire load is now being removed by the <br />American Tunnel Treatment Plaza <br />The steps below are the details of the calculation: <br />Actual Zinc Load at A-72: <br />actZn ,°°~ = Zn ~°„~ * flow *0.0054 {6) <br />where: <br />actZn ,°on =the actual zinc load at A-72 in pounds per day <br />Zn ~„° =the measured zinc concentration in ugJL <br />flow =the measured flow in cfs <br />0.0054 =the conversion factor <br />Expected Zinc Load at A-72: <br />where: <br />expZn i°aa = actZn ,°aa +CC ,°aa + AT,°ad -Kohl,°°a + Mog~°aa (7) <br />expZn ,°°a =the expected zinc load at A-72 in pounds per day <br />actZn ~°aa =the actual zinc load at A-72 in pounds per day <br />CC ~°aa =the expected load from Cement Creek due to cessation <br />of diversion and treatment of Cement Creek. (see below) <br />Kohl ,°ae =the expected load reduction from plugging the Koehler <br />Tunnel (estimated at 66.3 Ibs/day) <br />AT,°ad =American Tunnel residual load (30% of load after tae plug) <br />Mogi°°e =Mogul Mine residual (30% of load since Aug 2000) <br />z 70 percent was selected as the efficiency estimate for plugging the American Tunnel, the Mogul Mine and the <br />Koehler Mine. Experience of the Hazardous Materials and Waste Management Division at the Bonanza Mining <br />District has shown efficiencies of greater than 90 percent. <br />Appendix A 9 <br />232565 <br />