REV00083

• Permit No: C1981071
• IBM Index Class Name: Revision
• Doc Date: 9/1/1993
• Doc Name: SEDIMENT YIELD DEMONSTRATION BLOCK C
• Type & Sequence: SL3
• Media Type: D
• Archive: No

September 1993 CYVCC -Sediment Yield Demonstration - Block C ~ S
2.2 SEDIMENTOLOGY
Sediment yield was calculated by SEDCAD+ for single storm events for Block C and the
Pastureland Reference Area. SEDCAD+ develops a sedimentgraph utilizing the Revised
Universal Soil Loss Equation (RUBLE) using a new revised representative length-slope factor as
follows:
Y = 95(V x Qp)0.56K(LS)(CP)
Where: Y =Sediment yield in tons
V =Runoff volume in acre feet
Qp =Peak discharge in cfs
K =Soil erodibility factor
LS =Representative length-slope factor
CP =Control practice factor
The new length-slope factor for the RUSLE subroutine is as follows:
LS =~ a ) m x (slope factor)
72.6
Where: ~ =representative slope length (ft)
m = 0.6 for Slope > 10%
m = 0.4 Slope = 4`90
m = 0.3 Slope <4%
Slope Factor is a piecewise linear relationship with the slope break point being at 8Ro as shown
on Figure 5.5, Slope Factor for the Revised Universal Soil Loss Equation, in the SEDCAD+
Users Manual.
The sedimentgraph is then routed to a structure using an exponential decay procedure
incorporating deposition of a particle size distribution. The eroded particle size distribution is an
input item.
Inputs to the sedimentology component of the SEDCAD+ computer model include:
• Particle Size Distribution
• Runoff Volume
• Peak Discharge
• Soil Erodibility Factor
• Representative Slope Length
• Average Slope
• Control Practice Factor
• Sediment Specific Gravity
Particle Size Distribution. Particle size distribution analyses were conducted by CYVCC on 3
soil samples taken from the mine area. Analysis results are summazized in Appendix A.
Runoff Volume, V. Runoff volume is calculated by SEDCAD+ as previously described in the
Hydrology Section and is considered to be an internal input.
TERRAMATRIX • P.O. Bos 774018 ' Stentnbortt Springs, Co[orndo 80477 • (J03) 879-6260