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Mr. Jack Henris <br />October 19 2016 <br />Page 5 <br />m:\min\tc1\_teller\m-1980-244 cc-v\am -11\m-80-244-am-11-2ndmaincomment2016-10-19r4combined.docx <br />bullet) states “CNI agrees that a FOS of 1.5 for failure mechanisms that may <br />impact critical structures is appropriate, provided no prior experience has <br />been gained in historical mining of slopes in rocks with the same rock mass <br />characteristics and strengths… ” where “…CNI advocates for a minimum <br />FOS of 1.3…” This response does not explicitly offer any “historical <br />mining” that would support the acceptance of a FOS less than 1.5 for this <br />area. Please provide analysis results for a failure surface daylighting on the <br />slope side of County Road 82 and if it is less than 1.5, provide support that <br />historical mining has provided appropriate testing of similar rock for <br />characteristics and strengths to achieve a FOS of at least 1.3. <br />ii. Attachment 8 (September 2016 submittal). The CNI Figure 6-32 Section <br />GH-6 Global Analysis and Geology (Looking NE) depicts a failure surface <br />which daylights a considerable distance on the opposite side of Teller County <br />Road 82 from the high wall in question, indicating the road itself may have <br />a FOS considerably less than 2.219. Again referring to the response to <br />Comment 31.b (second bullet), please provide analysis results for a failure <br />surface daylighting on the slope side of County Road 82 and if it is less than <br />1.5, provide support that historical mining has provided appropriate testing <br />of similar rock for characteristics and strengths to achieve a FOS of at least <br />1.3. <br />31. Appendix 5 – Factors of Safety. <br />a. If a slope failure has the potential for off-site impacts… The acceptance of the <br />Division’s FOS criteria for potential off site impacts is adequate. <br />b. …Wiles (2000) suggesting the “coefficient of variation…” The response is <br />adequate provided the Division receives an adequate response to Comments 30.b(i) <br />and (ii) above. f <br />32. Appendix 5 Geotechnical Slope Recommendations, p. 5-8, Section 5.4.1. The response to <br />both Comments 32.a and b are adequate. <br />33. Appendix 5 Geotechnical Slope Recommendations, Table 5-1. The response is adequate. <br />34. Appendix 5 Section 6.3, Global Stability Analysis Results (p. 6-4). <br />a. Analyses showing adequate FOS exists to the edge of Right-of-Way for Teller Co <br />Rd 82. The response is not adequate. Please see Comment 30.b(i) above. <br />b. Analyses of additional cross sections for the Co Rd (perpendicular to Section WH- <br />3 and GH-4) and SGVLF (south of Section SI-2). The responses to the WH-4 and <br />SGVLF/SI-2 comments here are adequate. The response to the GH-4 comment is <br />not adequate. Please see Comment 30.b(i) above. <br />c. Justification for claiming high confidence in strength parameters if using a n FOS = <br />1.3. Acceptance of the 1.5 FOS criteria is adequate. <br />35. Appendix 5 Section 6.3.5, Figures 6-1 and 6-18. Please provide the following: