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M04007MT <br />for each analysis to help identify the potential theoretical slope <br />stability. A total of five (5) different cross sections are <br />presented with this report. Our discussions and data presentation <br />are based only on the calculated theoretical critical circle which <br />presented the lowest factor of safety against failure. Our <br />presentation does not include the results of all of the iterations <br />which resulted in a theoretical factor of safety greater than the <br />lowest factor of safety and therefore were not critical. <br />Our analysis was based on soil strength characteristics obtained <br />from laboratory triaxial shear strength tests of samples of soil <br />material remolded from on site material sources. Soil strength <br />characteristics presented in our 10 November 2003 Geotechnical <br />Engineering Study were also used during our analysis and are <br />summarized below. During the analysis for the preparation for the <br />10 November 2003 report we were instructed to use gob strength data <br />from other sources which were apparently from a different mine at a <br />different location. It appears that the material characteristics <br />were enough different between those from a different site and the <br />Bowie Number 2 mine site that these influenced the assessment <br />results. The soil strength values used in our analysis included: <br />' Site soil material (Reference: 10 November 2003 Geotechnical <br />Engineering Study): <br />' an internal angle of friction of twenty-four (24) degrees, <br />. cohesion of six hundred ninety (690) pounds per square foot <br />and <br />' a moist unit weight of one-hundred twenty-five (125) pounds <br />per cubic foot, and <br />' Wash Plant Coal Gob: <br />One-hundred (100) percent Coal Gob <br />' an internal angle of friction of nineteen (19) degrees, <br />' a cohesion of three hundred eighty-five (385) pounds per <br />square foot, and <br />. a moist unit weight of eighty-two (82) pounds per cubic foot. <br />4 <br />~Cam6ert anD ~,s,~ociates <br />CONSULTING GEOTECNNICAL ENGINEERS AND <br />MATERIAL TESTING <br />