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Water Requirements <br />The maximum annual consumptive use for this site is estimated at 49.1 acre-feet and will result <br />from evaporative losses and operational losses. Evaporative losses aze dependent on exposed <br />water surface azea, which includes settling ponds, dewatering trenches and collection basins. <br />Operational losses include water used for dust control and water retained in product hauled off <br />site. <br />The maximum exposed surface area at the site during mining is estimated at 1 acre. Total annual <br />evaporative loss is the product of net annual evaporation and total exposed groundwater surface <br />area. Net annual evaporation is difference between gross annual evaporation and effective annual <br />precipitation. <br />The NOAA Technical Report NWS 33, Evaporation Atlas for the ContiQUOUS 48 United States <br />(Ll.S. Department of Commerce) was used to determine gross annual evaporation. For this <br />location, gross annual evaporation was estimated at 45.04 inches. The Colorado Climate Center <br />climatic data for Brighton was used to estimate annual precipitation. For this station, average <br />annual precipitation was reported as 14.09 inches. Effective annual precipitation was assumed to <br />be 70% of average annual precipitation and was calculated to be 9.88 inches. The net annual <br />evaporation for this site is 2.94 acre-feet per acre or 2.94 acre-feet for the 1 acre of exposed <br />surface area. <br />The maximum annual production from the site is estimated at 1,500,000 tons. The moisture <br />content of the material hauled off the site was assumed to be 4 percent by weight. This results in <br />an annual amount of 44.15 acre-feet of water retained in the product. Dust control is required for <br />internal haul roads and stockpiles. Tota] annual water requirements for dust control aze <br />estimated at 2.0 acre-feet. <br />The estimated total annual consumptive use associated with the mining operation is summarized <br />as follows: <br />Eva oration 2.94 acre-feet <br />Moisture Retained in Product 44.15 acre-feet <br />Dust Control 2.00 acre-feet <br />TOTAL 49.09 acre-feet <br />Sources of Replacement Water <br />The replacement of consumptive uses will be accounted for in a Substitute Water Supply Plan <br />(SWSP) that is administered by the State Engineer. As a component of the SWSP, the operator <br />will provide the necessary water rights to mitigate all consumptive water uses during mining. <br />DMC 112 Permit <br />Page I S <br />