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n <br />Mr. William G. Merrill March 10, 2011 <br />Gunnison River Gravel Pit Nos. 1 & 5 Substitute Water Supply Plan Page 2 of 7 <br />In accordance with the letter dated April 30, 2010 (copy attached) from the Colorado <br />Division of Reclamation, Mining, and Safety ("DRMS"), all sand and gravel mining operators <br />must comply with the requirements of the Colorado Reclamation Act and the Mineral Rules <br />and Regulations for the protection of water resources. The April 30, 2010 letter from DRMS <br />requires that you provide information to DRMS to demonstrate you can replace long term <br />injurious stream depletions that result from mining related exposure of ground water. The <br />DRMS letter identifies four approaches to satisfy this requirement and requests the operator <br />provide this information to DRMS by April 30, 2011. It is our understanding that a financial <br />warranty is proposed to be utilized for Pits Nos. 1 and 5 to comply with this requirement. <br />Please confirm by April 30, 2011 if this is correct, or if another approach will be utilized. If <br />this requested information is not provided to the Division of Water Resources, any future <br />SWSP may limit the mining operation so that additional ground water cannot be exposed, <br />beyond that specified in this SWSP. <br />Depletions <br />Depletions at Pit Nos. 1 and 5 will occur as a result of evaporation from exposed ground <br />water, dust suppression, water removed with the mined product, dewatering, and water filling the <br />gravel pit as a result of material removal. <br />Net evaporative depletions were calculated using a gross annual evaporation of 55 inches <br />from the exposed water surface, and an effective precipitation amount of 6.2 inches. Based on <br />monthly average temperatures reported for the Grand Junction 6 ESE weather station, you have <br />estimated ice cover will occur on the ponds during the months of December and January; therefore <br />no evaporative consumptive use was estimated for those months. For the purposes of this SWSP, <br />the Applicant shall replace the net evaporative depletions from the exposed ground water surface <br />area that may occur during the assumed ice cover period (December and January) for any time that <br />the pits are not completely covered by ice. Net pond evaporation was calculated to be 46.25 inches <br />per year (3.85 feet per year) as shown on the attached Table 1. <br />Ground water will be used for dust suppression on the haul roads at the gravel pit sites and <br />for dust suppression purposes for the rock crusher operations. At Pit No. 1, you have estimated <br />0.34 acre-feet of water will be used per month for the three-month operating period (typically June <br />through August) for dust suppression on the haul roads, and 0.5 acre-foot of water will be used <br />during the month of July for dust suppression purposes at the rock crusher operation. At Pit No. 5, <br />you have estimated 0.81 acre-feet of water will be used per month for the ten-month operating <br />period (typically January through June and September through December) for dust suppression on <br />the haul roads, and 0.5 acre-foot of water will be used during the months of March and September <br />for dust suppression purposes at the rock crusher operation. <br />The amount of water retained in the material removed from each pit was calculated using a <br />value of 2 percent (by weight) for all sand/gravel mined below the water table because material <br />removed from the pits will not be washed and each pit will be in a dewatered state when material is <br />mined below the groundwater table. It is estimated that 72 percent of the sand and gravel deposit <br />will be excavated below the water table at Pit No. 1, and 76 percent of the sand and gravel deposit <br />will be excavated below the water table at Pit No. 5. Accordingly, approximately 0.75 acre feet of <br />water will be consumed as product moisture on an annual basis at Pit No. 1 (production rate of