2015-08-31_PERMIT FILE - C1981010 ‎(59)‎

• Permit No: C1981010
• IBM Index Class Name: Permit File
• Doc Date: 8/31/2015
• Doc Name: Reconstructed Drainage Channel Design Model
• Section_Exhibit Name: Appendix Q Section XXXVII
• Media Type: D
• Archive: No

Table 3
Summary of Appendix H SEDCAD sedimentology model results
Ten percent s/one
86
8.5
0.32
200
10%
1.00
1.00
114.82
18.13
4,806.0
83
8.5
0.32
200
10%
1.00
1.00
79.53
13.70
3,344.0
80
8.5
0.32
200
10%
1.00
1.00
51.36
10.11
2,208.0
78
8.5
0.32
200
10%
0.54
1.00
36.54
8.11
871.0
76
8.5
0.32
200
10%
0.54
1.00
24.22
6.38
605.0
72
8.5
0.32
200
10%
0.05
1.00
8.16
3.64
22.3
67
8.5
0.32
200
10%
0.05
1.00
1.73
1.37
5.4
62
8.5
0.32
200
10%
0.05
1.00
0.44
0.20
0.9
Fifteen
percent slope
86
8.5
0.32
200
15%
1.00
1.00
128.30
18.17
9,753.0
83
8.5
0.32
200
15%
1.00
1.00
89.30
13.70
6,805.5
80
8.5
0.32
200
15%
1.00
1.00
57.86
10.13
4,502.0
78
8.5
0.32
200
15%
0.54
1.00
41.19
8.12
1,777.0
76
8.5
0.32
200
15%
0.54
1.00
27.38
6.39
1,236.0
72
8.5
0.32
200
15%
0.05
1.00
8.68
3.64
43.9
67
8.5
0.32
200
15%
0.05
1.00
1.75
1.37
10.4
62
8.5
0.32
200
15%
0.05
1.00
0.44
0.20
1.7
In the models, it is necessary to enter a variety of sedimentation factors applicable to the
watershed. This includes the K factor, LS, C, and P values from the Revised Universal
Soil Loss Equation. As shown above, representative values have been used throughout.
In particular, the C (cover) factor is the most significant input. This variable is based on
the amount of bare ground.
Calculation of Annual Sediment Yield
When the SEDCAD models estimate sediment yield, it does so for that particular design
storm. In this case, this is the 10 year, 24 hour storm event. To convert this quantity of
sediment from the design storm to an estimate of the annual sediment contribution, a
manual conversion is needed. As described on page 6 of the SEDCAD instruction
manual, the following formula applies:
Ya = Ys (Ra / RS)
Where: Ya = Sediment Yield, Annual, ac -ft
YS = Sediment Yield, design storm, ac -ft
Ra = Annual Rainfall Erosivity factor
Rs = Rainfall Erosivity for this design storm.
In this case, Ra for Trapper Mine is 19 based on published data for this portion of Colorado
and Rs is provided in the SEDCAD model on the general input dialog box. For the 10
year, 24 hour storm event using 1.40 inches of rainfall, Rs is 8.50. Thus, the quantity of
9