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M04007MT <br />Seventy-five (75) percent Coal Gob, Twenty-five (25) percent on <br />site clay material <br />an internal angle of friction of twelve (12) degrees, <br />a cohesion of five hundred sixty (560) pounds per square <br />foot, and <br />a moist unit weight of ninety (90) pounds per cubic foot. <br />In our stability analysis we varied the soil strength values from <br />those listed above and the slope face inclinations from the <br />originally proposed two to one (2:1) (horizontal to vertical), to <br />assess the sensitivity of the analysis to varying soil strength <br />parameters. The variations in our analysis produced relatively <br />significant and predictable changes to the calculated theoretical <br />factor of safety indicating that the stability analysis was <br />sensitive to slight variances in the soil strength characteristics <br />of the coal gob and the constructed slope face inclination. <br />Our stability analysis was performed along a proposed cross <br />' section of the gob pile site provided by J.E. Stover and <br />Associates. The proposed cross section provided is located at or <br />near the maximum height of the proposed gob pile fill and has a <br />' height of about two-hundred-thirty (230) feet and a slope face <br />inclination of two to one (2:1) (horizontal to vertical). The <br />stability analysis of the proposed cross section indicates a <br />theoretical calculated factor of safety ranging from about .97 to <br />about 1.22 depending on the coal gob material strength <br />characteristics used. The theoretical calculated factors of safety <br />' were .97 which was associated with strength characteristics of the <br />75 percent gob/25 percent clay mix and 1.22 which was associated <br />with strength characteristics of the 100 percent gob. The slope <br />' stability analysis for the proposed gob pile is presented on <br />Figures A and B. <br />Our stability analysis was also performed along a similar <br />proposed cross section of the gob pile site, as referenced above, <br />located at or near the maximum height of the proposed gob pile <br />fill. However, the slope face inclinations were flattened above <br />fifty (50) vertical feet in the embankment to determine a <br />theoretical calculated factor of safety of 1.5 or greater. The <br />stability analysis of these proposed cross sections indicates a <br />theoretical factor of safety greater than 1.5 for slope face <br />5 <br />~Cam6ert ana ~s~,s~ociates <br />CONSULTING GEOTECNNICAL ENGINEERS AHD <br />MATERIAL TESTING <br />