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• <br /> <br />TABLE 13-3-3 <br />(COntinuedl <br />Watershed Flow Path <br />Hor. Diet. Vert. Dist. Land Use TC <br />9 1 1880 150 7 0.092 <br />9 la 560 20 7 0.041 <br />9 lb 320 30 3 0.014 <br />9. lc 9120 647 6 0.193 <br />9 ld 960 53 7 0.056 <br />10 6a 2800 75 7 0.236 <br />10 6b BBO 322 1 0.160 <br />10 6c 980 75 7 0.017 <br />11 lla 1320 46 7 0.082 <br />12 lib 1120 40 7 O.OB2 <br />Sedimentology. Tha SEDCAD+ computer program was utilized to calculate the sediment <br />flowing into and through [he principal spillway using the DEPOSITS portion of the program. <br />Sediment flow from the pond was calculated to be within the limits of the NPDES permit. <br />To determine [he sediment loading to the pond, the Average Annual "R" Method was utilized <br />to quantify Che sediment storage. The amount of sediment storage Ss determined for a <br />defined length of time and Is based on the design storm R, design storm sediment load, <br />average Annual R, and the number of years oL sediment storage desired. R is the rainfall <br />erosivity factor. The equation utilized for Required Sediment Storage is: <br />Required Storage ~ (Annual A) (NYears) (Storm Sediment Load) <br />Storm R <br />l/ <br />u <br />Annual R and the number of years are Snput. Storm R and Storm Sediment Load are <br />calculated for the design storm by Sed cad+. <br />A value of 30 for the average Annual R value and a period of one year was used. Sed cad+ <br />determined the required Sediment Storage for the one year period to be 2.44 ac-ft. The <br />amount of available sediment storage is 9.56 ac-ft 4elevation 6784.01• Therefore, when 60 <br />percent of the sedlmenC storage capacity has been consummed 15.74 ac-ft), the pond will be <br />cleaned out. <br />13-3A-5 Revlsetl 08/30/96 <br />