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<br />-31- <br />diversion point could be trucked to the site until the ponds were prepared or <br />replaced (p. II.C-106b). <br />The operation is in compliance with the requirements of this section. <br />IX. Probable H drologic Conse uences and Cumulative Hydrolo is Im acts <br />Assessment - Rules 2,0 .6 2, 3 and 2.0 .6 2 c <br />The projected hydrologic impacts of mining Federal Coal Leases C-23703, <br />D-047201, C-0126669, C-8424, and C-8425 have been added to the discussion of <br />cumulative impacts for all mine related activities. <br />Impact of the Mining Operation on Surface Water <br />Impacts to the hydrologic balance will occur as a result of the proposed <br />mine. Short term impacts which will occur as a result of surface facilities <br />appurtenant to the underground mine include reduction of water yield from the <br />mine plan area to the White River, increased sediment loads from disturbed <br />areas, and water quality degradation from the refuse disposal area. Long term <br />impacts will center on the effects of subsidence under Scullion Gulch and <br />Red Wash. See the subsidence section of this findings document for further <br />discussion of subsidence impacts. <br />Short term surface water loss will occur as a result of two factors: <br />retention of water in ponds and removal of water from the White River alluvium <br />(i. e. - Kenney Reservoir) by the well field. Runoff from disturbed areas will <br />be routed through sedimentation ponds, thereby reducing the amount of flow to <br />the White River. Evaporation losses wi]1 occur because the ponds will not <br />discharge run-off until some of the available storage volume is filled. Very <br />little of the impounded water will re-enter the ground water system due to the <br />clay liner installed in the pond during construction. Losses form the <br />D-Portal pond will be insignificant when compared to total run-off from the <br />Scullion Gulch watershed. The pond is designed to store run-off from 44 acres <br />while Scullion Gulch has a contributing drainage area of 7,552 acres at its <br />confluence with the White River. The refuse disposal area ponds receive <br />run-off from approximately 98 acres, which is a very small portion of the <br />2,950 acres drained by the Red Wash tributary through the northern sector of <br />the permit area. Based on this information, the net loss of surface water <br />quantity to Red Wash and the White River will be negligible. <br />The water supply for the mine will come from the White River alluvial well <br />field at a withdrawal rate of 1.34 cubic feet per second. This translates to <br />0.2 percent of the average annual flow in the river of 672 cfs. Even during <br />low flow conditions, when the average flow is 245 cfs, the withdrawal rate <br />will only be 0.55 percent of the available flow. Therefore, adverse impacts <br />on flow in the White River as a result of proposed withdrawal should be <br />minimal. Furthermore, the permittee has secured water rights downstream of <br />the mine that may be used if necessary to replace a depleted water source. <br />Construction of surface facilities in the permit area will cause temporary <br />increases in the amount of suspended solids in the surface water system. <br />Furthermore, concentration of chemicals associated with increased sediment <br />load, such as iron and manganese, will also increase. At the Deserado Mine, <br />mitigation of sediment load will be accomplished primarily by sedimentation <br />ponds. Although sediment increases will occur in the early phases of <br />