2012-11-07_HYDROLOGY - M1997054 - Laserfiche WebLink

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Stephen Buechner, Applegate Group Page 2 November 7, 2012 been obtained for $1,174,724 through the Division of Reclamation, Mining, and Safety ( "DRMS ") to assure that depletions from groundwater evaporation do not occur in the unforeseen event, or events, that would lead to the abandonment of the Pit. In addition, Front Range Aggregates owns and has dedicated fi ve shares of Twin Lakes Reservoir and Canal Company to cover these potential long term depletions. Front Range Aggregates must continue to commit those shares to this plan until such time as the State Engineer authorizes the release of this commitment. DEPLETIONS Consumptive use of water at the property consists of 8.51 acre -feet (Table 1) of evaporation from the 3.0 acres of exposed surface area within the settling ponds and the gravel washing pond (2.4 acres), a small sump used for filling water trucks (0.4 acres) and the dewatering trenches (0.2 acres), 9.37 acre -feet of water lost in product, and 9.0 acre -feet for on- site dust control (total 26.88 acre - feet -Table 2). The Applicant anticipates that 400,000 tons of aggregate will be mined at the site during this SWSP period. Computation of evaporation under this SWSP was also reduced during the ice covered period. You have assumed the ice covered period will occur during the months of December, January, and February based on the Canon City weather station average temperatures of 22.5 °F for December, 26.23 °F for January, and 24.13 °F for February. However, for the purpose of this SWSP, the Applicant shall replace the net evaporation depletions from the exposed ground water surface area that may occur during the assumed ice covered period (the months of December, January, and February) for any time that the exposed ground water in the pit is not completely covered by ice. Computation of the net evaporation during any time that the pond is not completely covered by ice shall be determined as the pro -rata amount of the monthly gross evaporation rate distribution amount identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro -rata amount of the effective precipitation for that period. You have provided a monthly breakdown of lagged depletions at this site in your attached Appendix A. The IDS Alluvial Water Accounting System ( "AWAS ") stream depletion model was used to determine the lagged depletions from dewatering, evaporation and operational losses to Arkansas River. The aquifer characteristics used in the model are: transmissivity (T) = 55,000 gallons per day per foot and specific yield (SY) = 0.2, the distance of the exposed ground water to the stream = 1,250 feet, and the location of the parallel impermeable boundary was estimated to be 2,400 feet from the stream. During this plan approval period, no ground water will be used for reclamation, concrete batching, or any other purpose. The total consumptive use and total lagged stream depletions were calculated to be 25.94 acre -feet for the 2012 -2013 approval period.