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To determine the sediment Io ceding to the pond, the Average Annual "R" Method vas utilized <br /> to quantify the sediment storage. The amount of sediment storage is determined for a <br /> defined length o f time and is based on the design storm R, design storm sediment load, <br /> average annual F, and the number of years of sediment storage desired. R is the rainfall <br /> erosivity factor. The equation utrli oed for Required Sediment S[o rage is: <br />Fequired _+to rage = (Annual F( IX 'i=arsl (Storm Sediment Lo adl <br />Storm F <br />Aran ual F and the number of years are input. S[erm F and Storm Sediment Load are <br />calculated fer the design storm by SEDCAD+. <br />A value of 30 for [he average Annual F value and a period of one year vas used. SEDCAD+ <br />determined the requited Sediment S[oiage fur the one year period to be 5.L1 ac-ft. The <br />amount of available sediment storage is 8.7 arft (elevation IOI0. 01. Therefore, when <br />the sediment s[o[ags capacity has been c~•nsumed, [he pond will be :leaned out. <br />Seneca Coal Company will monitor the s=dement stu rage capacity [o censure enougn caps uty' <br />• is available. The estimated design storm sediment 'aolume is based on a worst-rase <br />drs[urbance in the watershed, which is right now. The rofor _, [he constructed sediment <br />sto rag= capacity should be adequate for at leasr two years. <br />Fart v_le 51re Distnbua ons. The parilcle site distribution fer Lhis sediment pond was <br />based on sieve and hyd romecer analysis of various soil t}Pes in the Seneca II-W permit <br />area. This drstubutton rs repr=son tative o[ the watershed f~•r E'und 006 and based on a <br />werght=d average, see Table 13-4C-_. <br />5 Fevrsed 03/Dl/9B <br />• <br />