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C-1980-004 PR-2 10-Feb-2011 <br />PAR — Engineening/Geotech Page 5 of 5 <br />a) Printouts of stability evaluations have not been provided (TOC indicated they should be <br />found in Appendix Q. Please provide printouts for the Division's review. <br />b) Table 3 gives effective stress shear strength parameters of coal waste from CU triaxial <br />testing = 27.3', c'= 345psf), but these values are not carried over to Table 4, which <br />shows = 30', c'= 0 psf. Please review the parameters, revising as necessary, and <br />ensure that the intended parameters were utilized in the stability evaluations. <br />c) The text in Section 5.3 — Stability Evaluation Results, along with Table 5, has been <br />copied verbatim from the 2007 study. The Division believes this is an error. Please <br />review and revise as necessary. <br />d) Subsection 5.4.2 — This paragraph refers to the unit weight and internal friction angle of <br />coal waste, but does not mention any sensitivity related to cohesion of the coal waste. <br />Please review and revise or clarify if necessary. <br />9. Section 6.0 — Conclusions and Recommendations <br />a) The last sentence of the first paragraph gives a critical factor of safety of 1.7 for effective <br />stress analyses. Using a linear relationship, as described in the preceding paragraph, the <br />Division believes that FS = 1.6 for the measured 0 of 27.3' may be more accurate. <br />Please review the calculations, and revise if necessary. <br />2.10 Maps and Plans <br />1. 2.10.3(1)(c) requires the location of surface and subsurface manmade features within, passing <br />through, or passing over the proposed permit area to be shown on a map, while 0) requires a <br />map of the existing topography... in sufficient detail so as to represent slopes and <br />configuration of all surface features within the area to be affected. Figure 3.1-3 Original <br />Topography has not been updated since September 1985 and appears to represent only the <br />portal area of the canyon. Please provide a new map satisfying the requirements of <br />2.10.3(1)(e) )(1)(e) and 0) which shows the Pre-Mining Topography of the entire area proposed for <br />disturbance by Surface Facilities, using a 2' contour interval on the valley floor. <br />2. The current version of Figure 2.2-2 Surface Facilities, approved with MR48, uses a 2' <br />contour interval for the valley floor area. The same map, revised for PR-2, now depicts the <br />valley floor using only 10' contours. Please restore the 2' contour interval to the valley floor <br />portions of Figure 2.2-2 and add the single/double green line symbol (culvert pipes?) to the <br />Legend. <br />This concludes my preliminary adequacy review for PR-2 for the McClane Canyon Mine. <br />Please feel free to contact me with any additional questions you may have. <br />cc: Sandy Brown, DRMS <br />