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<br />• reviewed. The coal waste for this waste pile is generated off a screen as coal exits <br />the mine. The waste consists of material which does not break through the screen <br />and is judged to contain a high percentage of shale, sandstone, or siltstone. The <br />yvas~#e~ is general(y. more coarse and contains ,less fines than the washed waste <br />prev.jously investigated:` The following paragraphs summarize material properties. <br />Classification. The coal waste consists of coal, shale and sandstone <br />fragments. .Gradation tests from this"iri4estigati6ri indicate 65 to 72 percent gravel, <br />2630 33~percent sand and.2=to 3 percent silt and clay sized particles. The fines were <br />':; <br />generally non-plastic. Gradation test results are shown on Figs. 4 and 5. <br />Standard Proctor Testing. One standard Proctor moisture-density test (ASTM <br />D 698) was performed for this investigation on a sample of coal waste from a <br />composite sample of the bulk samples. The~P~oc~or test indicates a maximum dry <br />,~ <br />density of~1:.Q7.5..pcf with~an optimum moisture cbntenbof 9.5 percent (Fig. 6)is This <br />• value is considered a reasonable estimate for "typical" coal waste and is consistent <br />with our previous investigations. Ba§ed•~up,`on" 90' perceYn~? compaction and riear <br />optimum,4noisture content; a unit weighY'of 105 pef was used~in the analysis <br />Direct Shear Test Results. We performed a direct shear test on a sample of <br />the coal waste for this investigation. The test was performed on remolded samples <br />of the composite bulk samples at near optimum moisture contents. The results are <br />shown on Fig. 7 and provide a basis from which typical or minimum strength <br />estimates can be made. T.he,normal strength value used in our stability analysis <br />(~ _ 37 de'gr.,ees}and Cohesion = 200 psf) is showri on the plot. <br />STABILITY ANALYSIS <br />We performed a stability analysis of the existing coal processing waste pile <br />slope configurations. The analysis considered the results of the previous and <br />. current field and laboratory investigations. The computer aided stability analysis was <br />performed using the program Slope/WTM developed by Geo-Slope International Ltd. <br />BASIN RESOURCES, INC. <br />CTLJT 27,]97 S <br />