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0 <br />• Coal Waste. jTh;e~ stren.gifi 6a~ues used jfor ,the coaP :waste were j based <br />primarily uPori cljr'ect.shfeartesting 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 20,0 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`~df 1~05~ pcf <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 pef <br />were selected as normal parameters.. <br />• Bedrock. The bedrock consists of hard to very hard interbedded sandstone <br />and sandy shale. 1Ne dd:hot believe that asfailure through the bedrock layer is likely <br />due to the.high strengtty of the layer. <br />•Water:Col~ditio'~is. Two water conditions within the waste pile) were <br />considered. The first condition was for. hb water .and the second condition Vv'las for <br />a varying water .level from just above the bedrock su face at the toe of the ,waste <br />~. <br />pile, increasing uniformly to '/2 the pile height near the crest. <br />`J <br />OASIN RESOURCES, INC. <br />CTLfT 27.79] 7 <br />