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• <br />APPENDIX M(vii) <br />MUNGER CANYON MINE <br />COAL MINE WASTE DISPOSAL SITE <br />• <br /> <br />Notes for Calculations: <br />1. Pages M(vii)-2 & 3 present a spread sheet calculation of the required capacity of <br />the sediment pond based on the 10 year event. <br />2. Page M(vii)-4 is a ditch and culvert sizing summary. <br />3. CMP-1 is the western culvert. The peak flow for this culvert is calculated on <br />page M(vii)-13. CMP-2 is the middle culvert. It receives the peak flow from Ditch <br />D, 6.7 cfs. CMP-3 is the eastern culvert. It receives flow from a separate <br />drainage area. See calculation beginning on page M(vii)-33. <br />4. Ditches were sized using SEDCAD4. Ditches were sized using the 10 year and <br />100 year event as appropriate. Ditches A - F and I were sized with the 100-year <br />event so the size calculations for these ditches in the 10 year event section <br />(pages M(vii)6 - 21) should be ignored. <br />5. Page M(vii)-21 shows the peak flow using the 25-year event in the SEDCAD4 <br />program. This peak flow of 7.55 cfs was used to size the sediment pond <br />emergency spillway which is shown on page M(vii)-5. <br />6. The 100 year design of Ditch I does not account for the contributing flow from the <br />10 year design flow in Ditch G. This contributing flow is only 0.2 cfs which <br />increases the flow in Ditch I from 2.1 to 2.3 cfs. The flow depth in Ditch I only <br />increases 0.01 feet as a result of this small contributing flow. <br />7. A continuous silt fence will be installed above the reclaimed slopes to treat run- <br />off from the upland bare refuse slopes. The maximum slope length is 140 feet. <br />The silt fence was modeled assuming 100 feet of bare refuse slope above 40 <br />feet of reclaimed slope. <br />8. A berm will divert surface run-off away from the southern and western edges of <br />the sediment pond. <br />~NGINEER'S CERTIFICATION <br />~~~p RE6/sly <br />The calculations a ~ ~ttnga{~nented on pages M(vii)-1 through M(vii)-53 were <br />prepared by me d p~e mont~•t~~une and September, 2002, and the information <br />presented is true ~nct•~orr~~ th~be°st of my knowledge and belief. <br />a q <br />;~F•~13p;~S• Over, P.E. 'D te~ <br />R~w61 f°~'~essional Engineer <br />State o•#~olorado No. 19230 <br />M" <br />M(vii)-1 <br />9/02 <br />