Laserfiche WebLink
Volume V -Appendix M(viii) <br />Small Area Exemption No. 1 -SAE-2 <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 West 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 />A berm will be constructed at the disturbed/undisturbed interface to direct the upland <br />area runoff for Drainage Area No.5 into Ditch H and therefore will not be part of the <br />evaluation of SAE#1. <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 arid 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 .32/.24 25-feet <br />®~Ni3iNEER'S CERTIFICATION <br />The SEDCAD calculations as~,'in(oFm'afionp~esented on pages M(viii)-1ii, liii and M(viii)-1iv <br />were prepared under my®d~cY`supervis}ori<du~ing the month of March 2007, and the information <br />presented is true and co'ct`to the best of ryiy knowledge and belief. <br />m , ", <br />p ( ~J~ '~/ O~' <br />®o,~~fnes E. St__o1f ver, Pi Date <br />Regt`ed,Professional Engineer <br />Stat~da~~olq~ado; f to. 19230 <br />M(viii)-1 i 03/07 <br />