Laserfiche WebLink
The cross-section shown in Figure 2.2-7 is typical of the design fill. The slope of <br />the finished slope will be a relatively flat 3H:1 V. A rotational equilibrium analysis <br />was performed on this fill to determine its factor of safety. <br />The coal mine waste will be similar to the coaly material from the Loma loadout <br />placed at the Munger Portals. Lambert and Associates analyzed to coaly <br />material from the Munger Portal for triaxial shear strength tests. The coal <br />material has a cohesion of 3psi or 432 psf, a angle of friction of 33° and a density <br />of 82 pounds per cubic foot. Two strength values were used for the alluvial <br />colluvial material. Page 3-25 lists the following strength parameters that were <br />used for the alluvial colluvial material in the stability analysis. <br />Material Density Cohesion Angle of Friction <br />Alluvial 125 200 25 <br />colluvial 130 1300 15 <br />Coal Mine Waste 82 432 32 <br />• To provide a comparison, Powderhorn (Snowcap) Coal Company (SCC) used <br />the following strength parameters in its analysis of its two Cameo Refuse <br />Disposal Areas: <br />Material Density pcf Cohesion psf Angle of Friction <br />Coal Waste 84 200 32 <br />colluvial/Alluvial 112 0 32 <br />Ref: SCC permit Volume 4, Appendices 13-4 and 13-5. <br />The stability analysis assumes the fill will be well drained and that no pore <br />pressures will develop in the fill. The soil strength values were varied from those <br />listed above to assess the sensitivity of the analysis to varying soil strength <br />parameters. The variations in the analysis produced relatively small and <br />predictable changes to the calculated factor of safety indicating that the stability <br />analysis was not sensitive to slight variances in the soil strength values. <br />M" 2.2-12iv 6/02 <br />