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iii <br />Coal Waste. The strength values used for the coal waste were based <br />primarily upon direct shear testing performed during this investigation. Fig. 7 shows <br />the results of the testing and the normal value selected for use in the stability <br />analysis. The normal values were a friction angle of 37 degrees and cohesion of 200 <br />psf. We also evaluated conditions for a friction angle of 32 degrees and cohesion <br />of 200 psf as a worst case condition. The density of the coal waste was estimated <br />based upon the results of the Proctor test performed for this investigation. The <br />analysis is not sensitive to variations in unit weight. A moist unit weight of 105 pct <br />was used, <br />Soil Laver. The soil layer was included in the model as a continuous layer to <br />model a disturbed or mixed zone of soil/bedrock/refuse at the base of the waste pile. <br />We used a conservative strength value similar to a very sandy clay for this layer. A <br />friction angle of 25 degrees, cohesion of 500 psf and moist unit weight of 120 pcf <br />were selected as normal parameters. <br />Bedrock. The bedrock consists of hard to very hard interbedded sandstone <br />and sandy shale. We do not believe that a failure through the bedrock layer is likely <br />due to the high strength of the layer. <br />Water Conditions. Two water conditions within the waste pile were <br />considered. The first condition was for no water and the second condition was for <br />a varying water level from just above the bedrock surface at the toe of the waste <br />pile, increasing uniformly to Y2 the pile height near the crest. <br />dA51N RESOURCES, INC <br />CTL7 27,797 7 <br />