2021-02-04_HYDROLOGY - M2004013 - Laserfiche WebLink

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Kirystle Eiirvihn Page 4 of acre-feet. These estimates are based upon evaporative losses from the settling and washing ponds, mined cell, and dewatering trench, water removed in the mined product, and water used for dust suppression (see attached Table 1 A). Depletions associated with filling the increased volume of Pond 5 (10.38 acre-feet) were accounted for in this request. The volume was added to the total evaporation and operational losses in September 2021 and September 2022, and lagged to the stream. An instantaneous credit of 10.38 acre-feet from dewatering the pit to the river was removed from stream depletions in March 2021 and March 2022, when the area of the pond is reduced from 9.76 acres to 4.57 acres. Table 1 B shows that under Scenario B, the lagged stream depletions during the period January 2021 — December 2021 are estimated to be 34.02 acre-feet and the lagged stream depletions during the period January 2022 — December 2022 are estimated to be 35.06 acre-feet. These estimates are based upon evaporative losses from the settling and washing ponds, mined cell, and dewatering trench, water removed in the mined product, and water used for dust suppression (see attached Table 1 B). Depletions associated with filling the increased volume of Pond 5 (10.38 acre-feet) were accounted for in this request. The volume was added to the total evaporation and operational losses in September 2022, and lagged to the stream.An instantaneous credit of 10.38 acre-feet from dewatering the pit to the river was removed from stream depletions in March 2022, when the area of the pond is reduced from 9.76 acres to 4.57 acres. Table 1 C shows that under Scenario C, the lagged stream depletions during the period January 2021 — December 2021 are estimated to be 34.02 acre-feet and the lagged stream depletions during the period January 2022 — December 2022 are estimated to be 34.47 acre-feet. These estimates are based upon evaporative losses from the settling and washing ponds and mined cell (see attached Table 1C). Table 1 D shows that under Scenario D, the lagged stream depletions during the period January 2021 — December 2021 are estimated to be 28.67 acre-feet and the lagged stream depletions during the period January 2022 — December 2022 are estimated to be 25.29 acre-feet. These estimates are based upon evaporative losses from the settling and washing ponds, mined cell, and dewatering trench, water removed in the mined product, and water used for dust suppression (see attached Table 1 D). Table 1 E shows that under Scenario E, the lagged stream depletions during the period January 2021 — December 2021 are estimated to be 34.02 acre-feet and the lagged stream depletions during the period January 2022 — December 2022 are estimated to be 28.78 acre-feet. These estimates are based upon evaporative losses from the settling and washing ponds, mined cell, and dewatering trench, water removed in the mined product, and water used for dust suppression (see attached Table 1 E). REPLACEMENTS The proposed source of replacement water for this pit is a two year lease dated January 9, 2019 (through March 31, 2021) to deliver 19 acre-feet annually of fully consumable water from PBWW. The lease was extended on April 6, 2020 for five additional years. Beginning April 1, 2021, the annual quantity of water will increase to 46 acre-feet. The lease water will be provided from the Board's stored water at Clear Creek Reservoir, Turquoise Reservoir, Twin Lakes Reservoir, Pueblo Reservoir, from direct flow transmountain water, reusable return flows from transmountain water, or from any other reservoir or place from which the Board may legally deliver water.