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Stephen Buechner, Applegate Group Page 2 <br /> December 10, 2015 <br /> stream depletions that result from mining related exposure of ground water. <br /> In accordance with approach nos. 1 and 3, you have indicated that a bond has been <br /> obtained for $1,174,724 through DRMS to assure that depletions from groundwater evaporation <br /> do not occur in the unforeseen event, or events that would lead to the abandonment of the Pit. <br /> In addition, Front Range Aggregates owns and has dedicated five shares of Twin Lakes Reservoir <br /> and Canal Company to cover these potential long term depletions. Front Range Aggregates must <br /> continue to commit those shares to this plan until such time as the State Engineer authorizes the <br /> release of this commitment. <br /> DEPLETIONS <br /> The depletions that result from the mining operation over the period of this SWSP include <br /> evaporation from exposed ground water, dust suppression, dewatering, and water lost with the <br /> mined product. Evaporation losses will result from the exposure of ground water in the settling <br /> ponds, a gravel washing pond, dewatering trenches and two small sumps. The maximum exposed <br /> water surface area during the SWSP period will be approximately 4.0 acres consisting of 3.4 acres in <br /> the settling ponds and the gravel washing pond, 0.4 acres in the two small sumps and 0.2 acres in <br /> the dewatering trenches. <br /> Gross annual evaporation at the gravel pit location is estimated to be 46.0 inches per year <br /> and the monthly distribution is as depicted on the attached Table 1. Net evaporation is defined as <br /> gross evaporation less the consumptive use of water by vegetation that naturally occurred at the <br /> site prior to construction of the pit. The historical consumptive use was assumed to be equal to the <br /> effective precipitation, which was estimated based on the data from the Canon City weather <br /> station. The net evaporation for the exposed water surface is 37.2 inches per year, with a monthly <br /> distribution as shown on the attached Table 1 and using the estimated exposed water surface area <br /> of 4.0 acres, the total annual stream depletion resulting from the exposure of groundwater is <br /> estimated to be 11.28 acre-feet. <br /> Computation of evaporation under this SWSP was also reduced during the ice covered period. <br /> You have assumed the ice covered period will occur during the months of December, January, and <br /> February based on the Canon City weather station average temperatures of 22.5°F for December, <br /> 26.23°F for January, and 24.13°F for February. However, for the purpose of this SWSP, the <br /> Applicant shall replace the net evaporation depletions from the exposed ground water surface area <br /> that may occur during the assumed ice covered period (the months of December, January, and <br /> February) for any time that the exposed ground water in the pit is not completely covered by ice. <br /> Computation of the net evaporation during any time that the pond is not completely covered <br /> by ice shall be determined as the pro-rata amount of the monthly gross evaporation rate distribution <br /> amount identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand <br /> and Gravel Pits, subtracting the pro-rata amount of the effective precipitation for that period. <br /> You have provided a monthly breakdown of the annual depletions, which include 11.28 acre- <br />