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2024-2025 Chavers Mining Resources Substitute Water Supply Plan Page 3 of 8 <br /> July 25, 2024 <br /> Dust Control <br /> The estimated water used for dust suppression per year totals 1.25 acre-feet per year and 0.52 acre-feet <br /> for the period of August 1, 2024 through December 31, 2025, as shown on attached Table 3. <br /> Mined Product <br /> In addition to the evaporation, water is lost with the mined product removed from the mine site. The <br /> Applicant projects that they will produce 648,500 tons of gravel each year or 260,375 tons for the period <br /> of August 1, 2024 through December 31, 2024. Gravel mined will be in a dewatered state and will be <br /> washed, therefore the groundwater lost with the mined product during this period is estimated at four <br /> percent (4%) by weight. The water lost with the mined product is projected to total 19.08 acre-feet per <br /> year and 7.66 acre-feet for the period of August 1, 2024 through December 31, 2024, as shown on attached <br /> Table 3. <br /> Concrete Production <br /> As mentioned above, the water used for concrete production will be provided by the alluvial well [permit <br /> no. 80120-F (WDID 0206393)]. Assuming 30 gallons of water/cubic yard and 154,000 cubic yards of concrete <br /> production during the period of this SWSP, the estimated water used for concrete production is 14.18 acre- <br /> feet per year and 6.28 for the period of August 1, 2024 through December 31, 2024, as shown on attached <br /> Table 3. <br /> Total Consumptive Use: Evaporative and Operational Depletions <br /> Total consumptive use includes evaporative losses of 35.78 acre-feet, 19.08 acre-feet of water lost with <br /> the mined product, 1.25 acre-feet of water used for dust control, and 14.18 acre-feet of water used for <br /> concrete production. Total consumptive use per year is 70.29 acre-feet. <br /> Total consumptive use for the period of August 1, 2024 through December31, 2024 includes evaporative <br /> losses of 13.57 acre-feet, 7.66 acre-feet of water lost with the mined product, 0.52 acre-feet of water used <br /> for dust control,and 6.28 acre-feet of water used for concrete production. Total consumptive use through <br /> December 31, 2024 is 28.03 acre-feet. <br /> Lagged Depletions <br /> The IDS AWAS stream depletion model was used to determine the lagged depletions from evaporation, <br /> operational losses, and the alluvial well to the South Platte River. The model parameters used are shown <br /> in Table A below. <br /> Table A. IDS AWAS Model Parameters <br /> Distance from Distance <br /> Boundary Transmissivity Specific <br /> Well Name Condition boundary to stream (gpd/ft) Yield from well to <br /> (f ) ( ) <br /> (1) Aggregate Mining Alluvial Aquifer 7,500 85,000 0.2 575 <br /> (2) Aggregate Processing Alluvial Aquifer 7,500 85,000 0.2 1,275 <br /> (3) Concrete Production I Alluvial Aquifer 7,500 85,000 0.2 1,045 <br /> Annual lagged depletions are as follows: (1) 46.43 acre-feet associated with the evaporation from the pump <br /> basin and dewatering trench and water lost with mined aggregate, (2) 9.52 acre-feet associated with the <br /> evaporation from the wash pond and dust control,and (3) 14.52 acre-feet associated with the water pumped <br /> from the alluvial well for concrete production. The total lagged depletions per year equal 70.47 acre- <br /> feet as shown on attached Table 4. <br />