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DeBeque Gravel Pit SWSP Page 3 of 9 <br /> July 15, 2025 <br /> than 32°F taken from the Palisade weather station over the period of record 1911-2012. <br /> However, for the purpose of this SWSP, the Applicant shall replace the net evaporative <br /> depletions from the exposed groundwater surface area that may occur during the assumed <br /> ice-covered period (the months of December and January) for any time that the pit is not <br /> completely covered by ice. Computation of the net evaporation during any time that the pit <br /> is not completely covered by ice shall be determined as the pro-rata amount of the monthly <br /> gross evaporation rate distribution amount identified in the State Engineer's General <br /> Guidelines for Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro-rata <br /> amount of the effective precipitation for that period. <br /> Assuming ice cover during the months of December and January, the total annual <br /> evaporation from the exposure of groundwater is estimated to be 27.59 acre-feet per <br /> year, or 55.18 acre-feet for this SWSP period, as shown on attached Table 1. <br /> Aggregate Production <br /> An average of 75,000 tons of aggregate will be mined per year over a 22-day period in July. <br /> Since the material is mined in a dewatered state below the groundwater table, but not <br /> washed, two percent (2%) by weight of water is lost. Therefore, water lost with mined <br /> product is 1.10 acre-feet per year, or 2.20 acre-feet for this SWSP period, as shown on <br /> attached Table 2. <br /> Dust Suppression <br /> An average of 10,000 gallons per day over a 22-day period in July, in addition to 5 working <br /> days each month for two months before and after July, will be used for dust suppression. <br /> Therefore, water used for dust suppression is 1.29 acre-feet per year, or 2.58 acre-feet <br /> for this SWSP period. <br /> Intermittent Fill <br /> While actively mining, water will be pumped into a dewatering sump at a rate of 1,500 gpm <br /> located in the northwest corner of the gravel pit. The discharge point is also located in the <br />