2016-12-19_REVISION - M1980244 (2)

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3 was mined. This suggests the ECM / Altman backfill will not exceed an elevation of somewhere in the range of 10,450 and 10,600 feet (amsl). Response: Amendments 9 and 10 contained language indicating Altman backfill was planned to approximately 10,600 feet (amsl) and that actual backfill may vary according to economic and mining conditions. The Altman backfill elevation was built to approximately 10,730 (amsl) which does not include a top soil stockpile. The current ECOSA will blend together with the as-built Altman backfill to make one ECOSA facility. As demonstrated in Drawing C-4 and as discussed at the meeting between DRMS and CC&V held on November 9, 2016 the proposed final mining elevation of ECOSA facility is planned for 10,960 feet (amsl). An updated copy of Drawing C-4 is provided in Attachment 1. c. Section 12.4.2 Overburden Storage Areas. On page 12-9, fourth paragraph there is a statement that the height of the ECOSA will increase from that approved in Amendment 10 to 10,960 feet (amsl). This elevation is between 360 and 510 feet above what would be expected between those statements in comments N3.a and b above. Response: CC&V proposes to raise the height of the ECOSA from the 10,565 feet (amsl) to 10,960 feet (amsl) elevation. CC&V has surveyed the backfill material elevation from 10,600 (amsl) and plans to build to the final proposed ECOSA facility elevation of approximately 10,960 (amsl). This is 360 feet higher than proposed in Amendments 9 and 10. A revised geotechnical slope stability analysis, in Attachment 2, was completed to ensure stability of the proposed final ECOSA elevation to 10,960 (amsl). Volume III, Appendix 6 – Technical Memorandum N4. Stability Analyses Height Discrepancies. Figure elevations: Figure 2 indicates the maximum elevation of the ECOSA is 10,900 feet (compared to the 10,960 stated in Section 12.4.2). Figures 3, 4, and 5 suggest the crest elevation is 10,950 feet. The Attachment A stability model sections suggest a maximum elevation of 10,950 feet as well. Please confirm the analyses were performed for the 10,960 foot elevation stated in Section 12.4.2, or resubmit these analyses. Response: The “East Cresson Overburden Storage Area Stability Review/Update for Amendment No. 11 Permitting Submittal” in Attachment 2 contains Figure 1 which was intended to show the location of the cross-sections in plan view. Figures 2, 3, 4, and 5 are cross-sections displaying the correct final height of the ECOSA at 10,960 feet (amsl). As seen in Attachment 2, page 6, CC&V confirms the updated analysis was completed to the 10,960 feet (amsl) elevation. The updated geotechnical slope stability report, to construct the ECOSA to