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DeBeque Gravel Pit SWSP Page 3 of 10 <br /> August 7, 2025 <br /> Palisade weather station. The net evaporation for the exposed water surface is 40.01 inches <br /> per year, with a monthly distribution as shown on the attached Table 1. <br /> Computation of evaporation under this SWSP was reduced assuming ice-covered periods <br /> during the months of December and January based on average monthly temperatures less <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 29.84 acre-feet per <br /> year, or 59.68 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 SuQpression <br /> An average of 10,000 gallons per day over a 22-day period in July, in addition to five (5) <br /> working days each month for two (2) months before and after July, will be used for dust <br /> suppression. Therefore, water used for dust suppression is 1.29 acre-feet per year, or <br /> 2.58 acre-feet for this SWSP period. <br />