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F <br />Slope Stability of Reclamation Contours in South Portal Area <br />The following overburden characteristics were obtained from Stability <br />of Spoil Banks and Hollow Fills Created by Surface Mining by the Institute <br />of Mining and Minerals Research, University of Kentucky. <br />overburden density ('y): 75-150 lb/ft3 <br />cohesion (C'): 75-300 lb/ft2 <br />internal angle of friction (p): 25° to 35° <br />maximum height of embankment (H)= 50 feet <br />maximum slope grade = 4H :1V <br />the contact of the embankment with the original ground is <br />solid ( prior excavation to soild rock was necessary for <br />the portals) <br />Using the Bureau of Mines Report of Investigations 8564 titled Factor <br />of Safety Charts for Estimating the Stability of Saturated and Unsaturated <br />Tailings Pond Embankments, the cohesion factor was calculated using <br />conservative values from above. <br />C' = 75 = ,010 <br />YH 150 x 50 <br />~ = 25° <br />From Table A of R.I. 8564, the factor of safety for these conditions is <br />2.1. <br />Sensitivity <br />If the cohesion factor is 0.0 and the angle of friction is 25°, the <br />factor of safety becomes 1.95. <br />514 <br />