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qw, <br />Mr. Raul Passerini, P.E. Page 2 <br />March 19, 2014 <br />mining operators must comply with the requirements of the Colorado Reclamation Act <br />and the Mineral Rules and Regulations for the protection of water resources. The April <br />30, 2010 letter from DRMS requires that you provide information to DRMS to demonstrate <br />you can replace long term injurious stream depletions that result from mining related <br />exposure of ground water. The DRMS letter identifies four approaches to satisfy this <br />requirement. In accordance with approach no. 1 and 3, Everist obtained a bond for <br />$686,368.00 through DRMS for lining or backfilling of the exposed ground water. <br />Consumptive Use <br />The anticipated net depletions for this plan include evaporation of exposed ground water, <br />water lost in product, "first fill' water, water used for a crusher and wash plant, water used for dust <br />control, truck and vehicle washing, asphalt production, concrete batch plant operations, drinking <br />and sanitary use in an office, and water used for approximately 1 acre of landscape irrigation. You <br />have provided a monthly breakdown of the annual depletions made up of 109.67 acre -feet for <br />2013 and 111.02 acre -feet for 2014. The evaporation and operational losses associated with the <br />Maryland Creek Ranch site are summarized below: <br />Evaporation <br />Net evaporative depletions were calculated using a gross annual evaporation amount of <br />33.5 inches from the exposed water surface, an annual precipitation amount of 16.1 inches <br />(using the Dillon 1 E and Green Mountain Dam weather stations), and an effective precipitation <br />amount of 11.24 inches. Based on monthly average temperatures reported for the Dillon 1 E <br />station and the Green Mountain Dam station (see attached Table 1 for details), ice cover was <br />assumed for the months of November through March; therefore no evaporative consumptive <br />use was assumed for those months. For the purposes of this SWSP, the Applicant shall <br />replace the net evaporative depletions from the exposed ground water surface area that may <br />occur during the assumed ice cover period (November through March) for any time that the pits <br />are not completely covered by ice. The net depletion of ground water due to evaporation was <br />calculated to be 1.73 acre -feet per acre. The attached Table 2 displays the calculated unit <br />evaporation, the surface area of the cell ponds, and the monthly net evaporation corresponding <br />to 2013 and 2014. The net evaporation for 2013 is 52.68 acre -feet and for 2014 is 53.12 acre - <br />feet. <br />Water Lost with the Mined Product <br />Everist plans to mine approximately 292,000 tons of material during the 2013 and 298,000 <br />tons of material for 2014. Consumptive use associated with water retained in mined material was <br />calculated as 4 percent by weight for material mined below the ground water table and 2 percent <br />by weight for washed material mined above the groundwater table and were determined to be <br />approximately 8.57 acre -feet for 2013 and 8.76 acre -feet for 2014, as shown on the attached <br />Table 3. <br />Water Consumed by the First -Fill <br />For the Maryland Creek Ranch, the "first fill" was estimated based on 144,383 tons of <br />backfill material during the 2013 and 148,782 tons of backfilled material for 2014 multiplied by the <br />percentage gravel matrix (70% assuming a porosity of 30 percent and a density of the material <br />of 120 lb/cubic-foot) and then subtracting the volume of water lost with the mined product for <br />"Not Washed" gravel. Based on the above, the water removed by the "first fill' was determined <br />to be 30.55 acre -feet for 2013 and 31.14 acre -feet for 2014, as shown on the attached Table 3. <br />