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Volume V -Appendix M(viii) <br />Small Area Exemption No. 1 -SAE-1 <br />Calculation Rational and Results Summary <br />Silt Fence Design <br />Portal Area -Munger Canyon Mine <br />Purpose: <br />To control the runoff of water and sediment from the Munger Canyon Mine Site, after <br />final reclamation, a silt fence was designed. The silt fence will be installed to the East of <br />Ditch "H" as shown on Page M(viii)-1iv. <br />Rational: <br />Calculated using SEDCADT"" 4 for Windows <br />The landslope used in SEDCAD 2% and as such, berms will be constructed at a 2% <br />grade on both sides of the fence in order to direct the runoff to the fence. <br />Areas, slopes and flow paths obtained from the Sketch on following page M(viii)-1 iv. <br />The soil type in the study area is very gravelly clay loam <br />The following Curve Numbers were utilized in the calculations: <br />Mine Bench - 80 - C soil group, Herbaceous Mixture poor cover <br />Upland - 73 - C soil group, Herbaceous Mixture, poor cover <br />Table 2-2d Runoff curve numbers for grid and semiarid rangelands <br />10 year 24 hour storm event of 1.5" used in calculations to be conservative. <br />Results: <br />'.Structure ~ Peak~Flow.(cfs) in/out Size/Length <br />Silt Fence 1.03/.7 50-feet <br />The SEDCAD calculations <br />were prepared under my <br />presented is true and code <br />ied on pages M(viii)-1ii, 1iii and M(viii)-1 iv <br />the month of March 2007, and the information <br />wledge and belief. <br />°-e? ~ ~ <br />.~ n. <br />~"~th~s E. Stoye~;3Pa Date <br />Reg~ti1°prof~ siol+al Engineer <br />State of'~io~r~~e'~lo. 19230 <br />I <br />M(viii)-1 <br />03107 <br />