2021-02-04_HYDROLOGY - M2004013 - Laserfiche WebLink

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Krystle Ervin February 4, 2021 Page 3 of 7 and the maximum exposed area will be 9.76 acres. The total water consumption from sand production during the two years is estimated at 12.36 acre-feet. The total water consumption during the two years for dust suppression is estimated at 3.36 acre-feet. Your attached Table 1A shows the site net evaporation calculations (43.52 acre-feet) and water consumed by site operations (15.72 acre-feet). Under Scenario B during the time actively being mined, evaporation will occur from a maximum of 4.57 acres of water in the four settling and wash ponds and a dewatering trench. During the first year, the area of exposed water surface will be 9.76 acres, and during the second year the area of exposed water surface will vary. The total water consumption from sand production during the year of operation is estimated at 6.18 acre-feet. The total water consumption for dust suppression is estimated at 1.68 acre-feet. Your attached Table 1 B shows the site net evaporation calculations (56.02 acre-feet) and water consumed by site operations (7.86 acre-feet). Under Scenario C, evaporation will occur from exposure of a consistent 9.76 acres of water in four settling and wash ponds and in the mined cell during the years 2021 and 2022. Your attached Table 1 C shows the site net evaporation calculations (68.52 acre-feet) and water consumed by site operations (0 acre-feet). Under Scenario D, during the time when the cell is actively being mined, evaporation will occur from a maximum of 4.57 acres of water in the four settling and wash ponds and a dewatering trench. During the first year, the area of exposed water surface will vary, and the maximum exposed area will be 9.76 acres. After the slurry wall is constructed in March 2021, the area of exposed water will remain at 4.57 acres. The total water consumption from sand production during the two years is estimated at 12.36 acre-feet. The total water consumption during the two years for dust suppression is estimated at 3.36 acre-feet. Your attached Table 1 D shows the site net evaporation calculations (33.35 acre-feet) and water consumed by site operations (15.72 acre-feet). Under Scenario E during the time actively being mined, evaporation will occur from a maximum of 4.57 acres of water in the four settling and wash ponds and a dewatering trench. During the first year, the area of exposed water surface will be 9.76 acres, and during the second year the area of exposed water surface will vary. After the slurry wall is constructed in March 2022, the area of exposed water will remain at 4.57 acres. The total water consumption from sand production during the year of operation is estimated at 6.18 acre-feet. The total water consumption for dust suppression is estimated at 1.68 acre-feet. Your attached Table 1 E shows the site net evaporation calculations (51.56 acre-feet) and water consumed by site operations (7.86 acre-feet). You have provided a monthly breakdown of lagged depletions at this site for each of the aforementioned scenarios in your attached Tables 1A-1 E. The Glover stream depletion analytical model was used to determine the lagged effects of the evaporation and operational losses from the mine. The model was developed for depletions to the Arkansas River under the following assumptions: X=2,030 feet (the distance from the centroid of the exposed surface area to the river), 2) W=7,875 feet (the distance from the aquifer boundary through the exposed surface area to the river channel), 3) T=100,000 gal/day/ft (transmissivity of the alluvial aquifer between the well and the river), and 4) S=0.2 (specific yield). Table 1A shows that under Scenario A, the lagged stream depletions during the period January 2021 - December 2021 are estimated to be 34.98 acre-feet and the lagged stream depletions during the period January 2022 - December 2022 are estimated to be 37.06