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Mr. Jacob Bauer <br />April 25, 2011 <br />Page 2 of 5 <br />completion of a liner. The mining plan includes a slurry wall around the perimeter of the site <br />during mining. The slurry wall is in place; however, tests have previously indicated that there is <br />a leak in the liner. It is currently anticipated that the slurry wall liner will be fixed and approved <br />by June 30, 2011. <br />The mining operations are anticipated to conclude in June 2011. This plan will replace <br />all lagged depletions to the river that result from the mining operations. <br />Depletions <br />The depletions that result from the mining operation at the site consist of evaporation <br />from exposed surface area, water removed in the mined product, and water used for dust <br />suppression. <br />The total exposed surface area at this site is one (1) acre. Net evaporative depletions <br />were calculated using a gross annual evaporation of 45 inches from the exposed water surface, <br />with a credit of 10.8 inches for effective precipitation. The net depletion of ground water due to <br />evaporation from the 1.0 acre of ground water exposed at the site was calculated to be 2.86 <br />acre-feet for the period of this SWSP, as shown on the attached Table 2. <br />The Applicant has estimated that a total of 1.20 acre-feet of water will be used for dust <br />suppression from November 2010 through October 2011, as shown on the attached Table 2. <br />The material mined at the site will be below the ground water table but in a dewatered <br />state. The Applicant will not wash the mined material, therefore it will have a moisture content <br />of 2% by weight, and 2% will be charged because the moisture is a ground water diversion. <br />Based on the maximum production rate of 45,000 tons per month from November 2010 through <br />June 2011, 5.28 acre-feet of water will be removed with the mined product during this plan <br />period. <br />The Alluvial Water Accounting System ("AWAS") model was used with the alluvial <br />aquifer boundary condition option to lag depletions to the South Platte River. The following <br />parameters were used in the model: transmissivity (T) = 63,000 gallons per day per foot, <br />distance (X) from the surface of the exposed ground water to the river = 2,295 feet, distance <br />(W) from the aquifer boundary through the exposed ground water to the river channel = 3,836 <br />feet, and specific yield (SY) = 0.2. The location of the stream depletion is assumed to be <br />perpendicular to the river. Evaporative and operational losses were considered back to January <br />1, 2009 because depletions during this time period may still be impacting the river. <br />The site has been continuously dewatered since January 2009. Dewatering is expected <br />to occur at an approximate rate of 26.90 acre-feet per month from November 2010 through April <br />2011, at a rate of 13.46 acre-feet per month during May 2011, and to cease thereafter. During <br />dewatering, water is returned to the South Platte River at the same rate as dewatering occurs, <br />but results in delayed depletions to the stream system. Approximately half (13.45 acre-feet) of <br />the water removed during dewatering is placed in the Henderson Ski Lake, with the remainder <br />placed in the South Platte River. Accretions to the Henderson Ski Lake were lagged using the <br />following parameters: transmissivity (T) = 61,600 gallons per day per foot, distance (X) from the <br />Ski Lake to the river = 1,808 feet, distance (W) from the aquifer boundary through the Ski Lake <br />to the river channel = 5,300 feet, and specific yield (SY) = 0.2. The net effect to the river as a <br />result of dewatering is shown in the attached Table 3.