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<br />July 1996 CYVCC -Sediment Yield Demonstration Rev1- Block C • S <br />2.2 SEDIMENTOLOGY <br />Sediment yield was calculated by SEDCAD+ for single storm events for Block C and the Pastureland <br />Reference Area. SEDCAD+ develops a sediment graph utilizing the Revised Universal Soil Loss <br />Equation (RUBLE) using a new revised representative length-slope factor as follows: <br />Y = 95(V x QP)°S6K(LS)(CP) <br />Where: Y =Sediment yield in tons <br />V =Runoff volume in acre feet <br />QP =Peak discharge in cfs <br />K =Soil erodibility factor <br />LS =Representative length-slope factor <br />CP =Control practice factor <br />The new length-slope factor for the RUBLE subroutine is as follows: <br />LS ~ ~L !m x (slope factor) <br />72.6 <br />Where: ,l =representative slope length (R) <br />m = 0.6 for Slope > 10 percent <br />m = 0.5 4 percent < slope <10 percent <br />m = 0.4 Slope = 4 percent <br />m = 0.3 Slope <4 percent <br />Slope Factor is apiece-wise linear relationship with the slope break point being at 8 percent as shown on <br />Figure 5.5, Slope Factor for the RUBLE, in the SEDCAD+ Users Manual. <br />The sediment graph is then routed to a structure using an exponential decay procedure incorporating <br />deposition of a particle size distribution. The eroded particle size distribution is an input item. <br />Inputs to the sedimentology wmponent of the SEDCAD+ computer model include: <br />• Particle Size Distribution <br />• Runoff Volume <br />• Peak Discharge <br />• Soil Erodibility Factor <br />• Representative Slope Length <br />• Average Slope <br />• Control Practice Factor <br />• Sediment Specific Gravity <br />Particle Size Distribution. Particle size distribution analyses were conducted by CYVCC on three soil <br />samples taken from the mine area. Analysis results are summarized in Appendix A. <br />Runoff Volume, V. Runoff volume is calculated by SEDCAD+ ~ previously described in the Hydrology <br />Section and is considered to be an internal input. <br />Peak Discharge, Qo. Peak discharge is calculated internally within the SEDCAD+ program as <br />previously described and is considered to be an internal input. <br />C: l9ISic, rCJULYREV <br />°~i~wvs ~:3ip~.tq TenaMarrix lnc ' 165 South Union Boulevard Suite 460 • Lakewood, Colorado 80118 • (303) 703-S1,r0 <br />