2024-04-08_PERMIT FILE - M2024015

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Evaporative Loss Evaporative losses are dependent on the exposed water surface area, which may shift throughout the mining operation, but will not exceed the maximum. Exposed surface area at the Sweet Valley Pit mining site will include groundwater exposed in the dewatering trenches. The maximum exposed surface area at the site during mining is estimated at 0.75 acres. CCWCD plans to keep the site dewatered throughout the life of the mine. Evaporation data was taken from NOAA Technical Report NWS 33, Evaporation Atlas for the 48 Contiguous United States. The annual gross evaporation was determined to be 45 inches for this location. Monthly evaporation percentages are established by guidelines set by the State Engineer's Office. To determine precipitation, data from the National Weather Service for Greeley, CO (UNC) (1967-2023) was used. The long-term average precipitation at the Sweet Valley Pit mining site is estimated at 14.26 inches. Effective precipitation is calculated as 70% of the total precipitation. The net evaporation is the difference between gross annual evaporation and effective precipitation. The resulting net evaporation is 35.02 inches or 2.92 feet. The maximum annual evaporative loss from the 0.75 acres is 2.19 ac-ft. Operational Loss The average annual production from the Sweet Valley Pit mining site is estimated at 650,000 tons. Using 4% moisture content (2% for moisture in the product and 2% for water used to wash), the total associated consumptive use for water retained in the material mined and water used for washing the total associated consumptive use for water retained in the material mined is 19.1 ac-ft. Dust control use is 10,000 gal/day, 6 days/week, 4 weeks/month for 10 months of the year. This equates to 7.4 ac-ft. Maximum annual operational loss is estimated to be 26.5 ac-ft. Consumptive Use The maximum annual consumptive use (operational loss + evaporation loss) at this site during the mining operation is estimated to be 28.69 ac-ft. Replacement Water The replacement of consumptive uses at the site will be accounted for in a substitute water supply plan (SWSP) approved by the State Engineer. The SWSP will be obtained prior to any mining activities occurring that expose groundwater. Surrounding Water Rights The attached Figure A-1 Well Permits in the Sweet Valley Pit — Groundwater Evaluation by McGrane Engineering, LLC shows the permitted wells within 600 feet of the mining limits and permitted wells within the boundaries of the groundwater model/evaluation. The well information J&T Consulting,Inc. Central Colorado Water Conservancy District V I Sweet Valley Pit DRMS 112 Permit Application