1987-12-01_PERMIT FILE - C1981017 ‎(163)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: Mine Portal Areas Drainage and Sediment Control Plans
• Section_Exhibit Name: Chapter II Attachment 1 to Appendix II-B-7
• Media Type: D
• Archive: No

4. SEDIMENT YIELDS
• a. Soil Losses derived by Universal Soil Less Equation
Soil Loss A = RKLS CP tons/acre Ref: SCS Tech Note 50
- F A C T 0 R S -
Drainage Soil Length Control Annual Sediment-
Area Rainfall Erodability Slope Practice Losses-Factor A
R K LS CPtons/acre AF/acre 1 /
Pad 1 40 .42 3.50 1 58.8 0.0390
Pad 2 40 .40 0.66 1 10.5 0.0069
Pad 3 40 .40 0.43 1 6.9 0.0045
Pad 4 40 .40 0.28 1. 4.5 0.0030
Density 70 pcf
1 ton/acre * 1 * acre * 2000 lbs = 0.000656 ac/ft
70 pcf 43560 ft2 1 ton acre
b. Soil Erodability
Observed general soil conditions as follows:
A11 Pad Areas / Slopes
1) %Gravelly to stoney rock fragment 30 to 80 30 to 50%
2) % Clay silt-fine sand 50 60%
3) % Sand 20 20%
4) % Organic matter 0 1%
5) Soil Structure 4 1 to 2%
6) Permeability 6 3 to 4%
7) Soil Erodability 0.40 0.60
C. Estimated Annual Yield of Sediment Delivered To Ponds
Sediment Estimated
Drainage Unit Sediment Delivery Annual Sediment Yield
Area Area Loss-Factor A Ratio
(acres) (acre feet/acre) *1 ac.ft/acre otal ac.ft ! ft.)
Pad 1 2.38 0.0390 0.8 0.0312 0.074 3220
Pad 2 0.75 0.0069 0.8 0.0055 0.004 174
Pad 3 0.44 0.0045 0.7 0.0032 0.0014 61
Pad 4 1.14 0.0030 0.7 0.0021 0_0024 105
• TOTAL 0.0818 .c- f t
*1 Estimated Sediment Delivery Ratio for Bare Ground
Steep Slopes - 90% of Gross Erosion is Sediment Yield
Flat Pads - 701'. of Gross Erosion is Sediment Yield
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