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Mike Boulay <br />-26- October 16, 2012 <br />MCM: No longer applicable, expanded coal mine waste pile no longer planned. <br />Stability analysis will therefore revert back to analysis approved with TR -16 and <br />as included in Appendix R. <br />b. Table 3 gives effective stress shear strength parameters of coal waste <br />from CU triaxial testing (cp = 27.3 °, c' = 345psf), but these values are not <br />carried over to Table 4, which shows cp = 30 °, c' = 0 psf. Please review <br />the parameters, revising as necessary, and ensure that the intended <br />parameters were utilized in the stability evaluations. <br />MCM: No longer applicable, expanded coal mine waste pile no longer planned. <br />Stability analysis will therefore revert back to analysis approved with TR -16 and <br />as included in Appendix R. <br />c. The text in Section 5.3 — Stability Evaluation Results, along with Table 5, <br />has been copied verbatim from the 2007 study. The Division believes this <br />is an error. Please review and revise as necessary. <br />MCM: No longer applicable, expanded coal mine waste pile no longer planned. <br />Stability analysis will therefore revert back to analysis approved with TR -16 and <br />as included in Appendix R. <br />d. Subsection 5.4.2 — This paragraph refers to the unit weight and internal <br />friction angle of coal waste, but does not mention any sensitivity related to <br />cohesion of the coal waste. Please review and revise or clarify if <br />necessary. <br />MCM: No longer applicable, expanded coal mine waste pile no longer planned. <br />Stability analysis will therefore revert back to analysis approved with TR -16 and as <br />included in Appendix R. <br />63. Section 6.0 — Conclusions and Recommendations <br />a. The last sentence of the first paragraph gives a critical factor of safety of <br />1.7 for effective stress analyses. Using a linear relationship, as described <br />in the preceding paragraph, the Division believes that FS = 1.6 for the <br />measured cp of 27.3° may be more accurate. Please review the <br />calculations, and revise if necessary. <br />MCM: No longer applicable, expanded coal mine waste pile no longer planned. <br />Stability analysis will therefore revert back to analysis approved with TR -16 and <br />as included in Appendix R. <br />