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Nelson Mining Resources SWSP <br /> November 25, 2024 <br /> Page 4 of 11 <br /> estimated water used for dust suppression during the period of this SWSP total 1.74 <br /> acre-feet as shown in Table 3, column 3. <br /> The anticipated annual depletions for this plan are estimated at 30.29 acre-feet for <br /> up to 8.00 acres of water surface exposed at the site. You have provided a monthly <br /> breakdown of the annual depletions made up of 21.18 acre-feet per year of <br /> evaporative loss, 1 .74 acre-feet per year of water used and consumed for dust <br /> control, and 7.37 acre-feet per year of water lost with the mined product, which <br /> represents 250,000 tons of aggregate production (Table 5). <br /> The IDS Alluvial Water Accounting System (AWAS) analytical stream depletion model, <br /> which uses the Glover method, was used to calculate the lagged depletions to St. <br /> Vrain Creek. The following parameters were used in the model: transmissivity (T) _ <br /> 30,000 gallons per day per foot; specific yield (SY) = 0.2, the distance (X) from the <br /> centroid of the exposed ground water surface to the creek = 2,126 feet, and the <br /> distance (W) from the aquifer boundary through the well to the creek channel = 3,700 <br /> feet. The total lagged depletions were determined to be 22.76 acre-feet during the <br /> period of this SWSP, as shown on the attached Table 5, column 3. <br /> Dewatering <br /> Dewatering during this plan period will be at an average rate of 500 gpm/month and <br /> directly discharged to Saint Vrain Creek. Based on this rate approximately 806.52 <br /> acre-feet will be pumped from the site during this plan period (Table 4). The <br /> dewatering activities were lagged using the same aquifer parameters as the <br /> evaporative depletions, resulting in lagged depletions to the river of approximately <br /> 806.23 acre-feet (Table 5, column 4). The net effect on the river from dewatering <br /> shows that during the period of this SWSP there is an accretion to the river of 0.29 <br /> acre-feet, as shown in Table 5 (column 2 - column 4). All dewatering activities must <br /> be metered with a totalizing flow meter that is recorded and reported on the <br /> submitted monthly accounting. <br />