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Nelson Mining Resources SWSP <br /> November 25, 2024 <br /> Page 3 of 11 <br /> Depletions <br /> The projected depletions for the period of this SWSP consist of net evaporation from <br /> exposed groundwater surface area, water lost with the mined product, dust <br /> suppression and dewatering. A total of 8.00 acres of water surface are exposed at the <br /> site in the mining pit basin pond (3.73 acres) sedimentation pond #1 (1.65 acres), <br /> sedimentation pond #2 (2.25 acres), and dewatering trenches (0.37 acres) . <br /> Evaporation and Mining Operations <br /> The Applicant proposed to replace evaporation from exposed ground water at the site <br /> based upon evaporation atlases in NOAA Technical Report NWS 33 and the SEO <br /> monthly distribution factors for sites below 6,500 feet, as shown in attached Table 2. <br /> Gross annual evaporation at the gravel pit location is estimated to be 41 inches per <br /> year. Net evaporation is defined as gross evaporation less the consumptive use of <br /> water by vegetation that naturally occurred at the site prior to construction of the <br /> pit. The historical consumptive use was assumed to be equal to the effective <br /> precipitation, which was estimated based on the data from the Colorado Decision <br /> Support System (CDSS) NOAA US1 COWE0302 weather station and CoCoRaHS Data <br /> (record August -2007 through July -2024). The net evaporation from the estimated <br /> exposed water surface is 20.20 acre-feet from the sedimentation ponds and 0.98 acre- <br /> feet from the dewatering trenches for a total of 21.18 acre-feet for the November 1, <br /> 2024 through October 31, 2025 period, as shown in Table 2, column 10. Computation <br /> of evaporation under this SWSP was not reduced for any assumed ice covered periods. <br /> In addition to the evaporation, water is lost with the mined product removed from the <br /> mine site. The Applicant projected that they will produce 250,000 tons of gravel <br /> during the SWSP period. Gravel mined will be in a dewatered state and will be washed <br /> therefore the ground water lost with the mined product during this period is <br /> estimated at 4 percent by weight. The water lost with the mined product is projected <br /> to total 7.37 acre-feet during the SWSP period, as shown in Table 3, column 2. The <br />