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C -1980 -007 TR -120 <br />2 nd AR — MLT <br />01- Apr -2010 <br />Page 3 of 3 <br />20. A minimum static safety factor of 1.5 is required by 4.10.4(2). The "Permit Design" <br />configuration modeled in Figures 2 -9 and 2 -10 of the original application resulted in a <br />static Factor of Safety of 1.82 and a seismic Factor of Safety of 1.58. These factors may <br />be reduced slightly by the change in friction angle for the refuse material, but are still <br />likely to exceed the requisite values. Please revise the Permit Design model runs of <br />Figures 2 -9 and 2 -10 to reflect the change in refuse friction angle derived from the LRP <br />investigation. <br />MCC's 23 March response indicates that additional model runs were completed. <br />The results are reflected in the revised text of Section 2.2. However, the electronic <br />submittal did not include revised Figures 2 -9 and 2 -10 for the "Permit Design" <br />configuration. <br />Please provide updated versions of Figures 2 -9 and 2 -10, reflecting changes made to <br />the model, for inclusion with Exhibit 82. <br />General Review Comments <br />21. 2.1— Geotechnical Investigation describes the soil and rock borings drilled for the <br />borehole locations for the RPE East investigation are shown on Drawing No. C -02 in <br />Appendix D. For ease of reference, it would be helpful if the same (or a similar) drawing <br />were also included as Figure 1 -3. Please add Figure 1 -3 to Volume IOC, illustrating the <br />borehole locations for the RPE East geotechnical investigation. <br />MCC's 23 March indicates that Figure 1 -3 has been added, but the figure was not <br />included with the electronic submittal. <br />Please ensure that Figure 1 -3 has been or will be provided for incorporation into <br />Exhibit 82. <br />22. The last two sentences of 2.2.3.1 Refuse Pile Configuration refer to Figure 2 -5 and Figure <br />2 -6, respectively. The first reference should be to Figures 2 -5 and 2 -6, while the second <br />should be to Figures 2 -7 and 2 -8. Please ensure that the intended figures are referenced <br />in this subsection. <br />The text has been corrected. Item resolved; no further action is required. <br />This concludes my second adequacy review for TR -120 at the West Elk Mine. Please do not <br />hesitate to contact me with any additional questions that you may have. <br />cc: Sandy Brown, DRMS <br />