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Table 4.8-1 Water Depletion Calculation <br />Revised (PR-11, 2022) Estimate of Annual Use and Evaporative <br />Loss of Surface Waters Discharged From Trapper Mine <br />Evaporative Depletion From Impoundments <br />o Assume annual evaporative loss is 24 inches. <br />o 41 existing sediment ponds average 0.63 acres <br /> surface area at high water mark = 41 * 0.63 ac * 2' = 51.66 ac-ft <br />o Coyote Dam @ high water mark = 1* 12.00 ac * 2' = 24.00 ac-ft <br />o Future life-of-mine sediment ponds = (3 * .68) ac * 2' = 4.08 ac-ft <br />o Existing stock ponds (55) @ average 0.13 ac = 55 * 0.13 ac * 2' = 14.30 ac-ft <br />o Future life-of-mine stock ponds (10) = 10 * 0.13 ac * 2' = 2.60 ac-ft <br />Total = 96.64 ac-ft <br />Depletion Due to Road Watering <br />o Average annual quantity used for road watering. Total = 123.79 ac-ft <br />Total Estimated Depletion = 96.64 ac-ft <br />123.79 ac-ft <br />220.43 ac-ft <br />Augmentation Due to Deep Wells/Pit Pumpage <br />o Assume 10% of pit water originates from surface runoff. <br />o Average annual Trapper well dewatering. = 37.06 ac-ft <br />o Average annual Trapper pit dewatering = 44.30 * 0.9 = 39.87 ac-ft <br />Total Augmentation = 76.93 ac-ft <br />Total Adjusted Depletion Due to Mining - 2022 Estimate (PR-11):220.43 ac-ft <br />-76.93 ac-ft <br />143.50 ac-ft <br />Total Adjusted Depletion Due to Mining - 2012 Estimate (PR-07):*160.10 ac-ft <br />*Highest previous value. <br />4-172a