PERMFILE69474

• Permit No: C1994082A
• IBM Index Class Name: Permit File
• Doc Date: 9/27/2007
• Doc Name: Drainage and Sediment Control Plan
• Section_Exhibit Name: Tab 13 Attachment 13-12
• Media Type: D
• Archive: Yes

February 1999 Yaan Mine * 13-77 Drainage anti Sed~mcnt Coxtrot Plan ~ 9
A force limit equilibrium stability analysis was completed using the Slope/W softwaze package. A
. Morgenstern Price analysis was used in conjunction with a seazch routine to estimate the lowest
safety Factor for the embankment. This method satisfies both moment and force equilibrium of a
given analysis.
For the worst-case scenario, embankment geometry with the following chazacteristics was used:
• Embankment Crest Width: 5 Feet
• Downstream Slope Height: 9 Feet
• Downstream Slope Angle: 2H:1V
• Upstream Slope Height: 8 Feet
• Upstream Slope Angle: 2H:1V
• Height Erom Spillway Invert to Upstream Slope Toe: 5 Feet
The embankments are constructed from spoil material produced during mining. This material was
placed in controlled lif[s and compacted. Based on this fact, observations of the onsite spoil piles,
and typical strength values For spoil material, the following strength properties were assigned to the
embankment.
Spoil: ~ = 38°; cohesion = 0 psi
Unit Weight = 120 pcf
Based on these assumptions, a safety factor of 1.56 was calculated by the limit equilibrium analysis. Rule
4.05.9(8)(6) states that stock ponds shall have a minimum static safety Eactor of 1.3. Based on this analysis
and tha[ the Yoast Mine will use the same construction methodology, it is concluded that the proposed
stock pond designs will meet or exceed the minimum safety criteria established in Rule 4.05.9.
9.0 REFERENCES
Barfield, Wazner, & Haan (1981). Applied Hydrology and Sedr'mentology forDirturbedArear. Oklahoma
Technical Press, Stillwater, Oklahoma.
Colbond Inc., Product Specification Information, Enka, North Carolina 28728, www.colbond-
usa.com
Erosion Control Technical Council, 2006. Standard SpeciFcations For Rolled Erosion Control
Products, St. Paul, Minnesota 55118, www.ectc.org
Greenfix America, Product Specification Information, Brawley, California 92227,
www.greenfix.com
Nyenhuis, J. (Dec. 1997). Seneca II W South Expanrion Soi! Survey.
North American Green, Product Specification Information, Evansville, Indiana 47725,
www.nagreen.com
Renard, I{. G., G.R. Foster, G.A. Weesies, D.K. McCool, and D.C. Yoder, coordinators (1996). Predicting
Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss
Equation (RUBLE). Agricultural Handbook No. 703. U.S. Department of Agriculture. ~nal dra~
Schwab and Wazner (1998); SEDCAD4 Derign Manual and Urer'r Guide. University of Kentucky,
Biosystems and Agriculrural Engineering Department.
Montgomery Watson Minixg Group * 168 S. Union Bou/cvarrl, Suite 460 * Lakewood, Colorado 80228 * [phone]
TR-30 Revised 03/07