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SEDIMENT YIELD <br /> Estimated <br /> • Unit Total <br /> Sediment Combined Sediment <br /> Area Yield Delivery Sediment To Pond <br /> Sub Area Acres Condition ad. ft/ac. Factor Factors ac. ft. <br /> Yard 1 4.99 Vegetated 0.08 0.8 0.065 0.324 <br /> Natural <br /> Yard 2 5.36 Disturbed 0.1 1.0 0.10 0.536 <br /> Pad Area <br /> Pond/ <br /> Waste 1 12.0 Permeable 0.10 0.9 0.09 1.080 <br /> Waste Pile <br /> 2 4.77 Natural* 0.08 0.8 N/A N/A <br /> 3 4.75 Ponds* 0 --- 0 N/A <br /> *Sediment diverted via ditches Total Sediment Yield 1.940 ac.ft./yr. <br /> Suggest semi-annual clean out thus re- <br /> quired storage, of Sediment = 0.820 ac.ft. <br /> POND DESIGN CRITERIA <br /> a) Capacity for Storage of 10-yr. Storm Runoff <br /> Sediment (semi-annual) 0.82 ac. ft. <br /> 10-yr. runoff storage 5.28 ac. ft. <br /> Total Storage 6.10 ac. ft. <br /> 100% Stored w/Q = 1 to 2 CFS Percolation Rate into Ground <br /> UndergrounS mine effluent - 2 cfs <br /> 10 yr. storm to be dissipated by permanent storage and percolation <br /> into ground. Must be verified in field. <br /> b) Emergency Spillway Q = CLH 3/2 = 3.087 (L' ) H 3/2 <br /> Q = 12 CFS $roadcrest Weir (Concrete) <br /> Invert Elev. 8338.53 <br /> L = 11 ft. H = 0.50 ft. with 1 ft. freeboard above HWL <br /> g <br />