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Section 780.21 (b) Continued. <br />will be adequately handled. Therefore, any possible adverse effects <br />with respect to surface water quantity would be the result of <br />decreased volumes of water available in the mine plan area and <br />for downstream uses such as artificial irrigation, natural irri- <br />gation, public water supply, livestock needs, wildlife needs, and <br />certain industrial and commercial needs. <br />Methods of Protection and Mitigation <br />Energy Fuels intends to utilize numerous methods to minimize the <br />potential reduction in downstream water availability and to miti- <br />gate any adverse effects, if necessary. Sedimentation ponds are <br />the single most important contributor to potential reduction in <br />downstream water availability. As discussed in detail below, <br />the ratio of water permanently impounded to the total discharge of <br />the subject watershed is very low. Sedimentation ponds will have <br />dewatering devices installed so that most of the detained water can <br />• be released after it meets all applicable effluent limitations. <br />The volume remaining in all ponds, except Pond A, will be that of <br />the design sediment storage volume. Since all ponds will be cleaned <br />out when the sediment volume reaches 60% of its design volume, the <br />average volume of sediment volume will be 30% of the design volume. <br />Therefore, the average volume of water remaining in the ponds, or <br />"dead storage", will be 70% of the design sediment storage volume. <br />Sedimentation pond A will have a dewatering system that will eli- <br />minate all dead storage. <br />Designs of all sedimentation ponds are discussed under Sections <br />780.25, 816.46, and 816.49, in Exhibit 13, Sedimentation Ponds - <br />Hydrologic Investigations, and Exhibit 14, Sedimentation Ponds - <br />Geotechnical Investigations. The total volume of dead storage <br />capacity in all sedimentation ponds equals 16.17 acre-feet for the <br />Fish Greek Watershed, 3.71 acre-feet fox the Middle Creek Water- <br />shed, and 36.26 acre-feet for the Foidel Creek Watershed. The mean <br />annual discharge volume of Fish Creek just upstream of the mine <br />780-160 <br />