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Sediment Loading <br /> All runoff from areas disturbed during the life of mine will pass through one <br /> of five sedimentation ponds prior to leaving the permit area. Discharges from <br /> the ponds will be required to meet NPDES effluent limits, and should, <br /> therefore, not contribute additional suspended solids to stream flows near the <br /> permit area. <br /> Following reestablishment of drainage channels and vegetation during <br /> reclamation, more runoff from the mine area will occur. However, sediment <br /> loads in that runoff should be no larger than those currently coming from the <br /> permit area. <br /> Quantity of Surface Flows <br /> The largest peak flow recorded in Armand Draw during baseline data <br /> collection was 0.595 efs. The presence of a sediment pond in Annand Draw <br /> will attenuate peak flows in that drainage during mining. After mining, flows <br /> in Annand Draw will increase due to establishment of spoil springs and <br /> additional runoff from the reclaimed area. Spoil springs are projected to add <br /> approximately 0.073 cfs of base flow to Annand Draw. <br /> Spoil springs in Armand Draw and the Pond 11 drainage will add year-round <br /> base flow to Grassy Creek. These spoil spring contributions are projected to <br /> increase mean flows during irrigation season (June 1-September 30) in <br /> Grassy Creek from 0.25 to 0.37 cubic feet per second downstream from the <br /> Yeast Mine. <br /> Spoil springs are projected to add approximately 0.159 cfs of base flow to <br /> Sage Creek during irrigation season (June 1 — September 30). These spoil <br /> spring contributions are projected to increase mean flows during the irrigation <br /> season in Sage Creek from 0.259 to 0.418 cfs. <br /> Quality of Surface Water <br /> The primary impact of Yoast mining operations on surface water quality will <br /> be an increase in total dissolved solids concentration resulting from the <br /> occurrence of spoil springs after backfilled spoil in the mine pits has become <br /> saturated. Using conservative assumptions regarding the amount of inflows <br /> to the reclaimed pits, and the quality of spoil spring water, and information <br /> gathered from the nearby Seneca II Mine in recent years, Seneca Coal <br /> Company has estimated the changes in surface water quality which may be <br /> caused by the proposed Yeast Mine. The projected impacts on each of the <br /> affected drainages near the permit area are summarized below. <br /> Yoast Mine 27 October 19. 1999 <br />