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To: Jared Ebert <br /> Date: January 2, 2018 <br /> Page 32 <br /> Comment 55 <br /> Please update the Exhibit C — Mine Plan Map to indicate the required fifty (50)foot <br /> offset from all permanent man-made structures. <br /> Response 55 <br /> Exhibit C (Attachment 1) has been updated to show the 50-foot offset during mining. <br /> Comment 56 <br /> The General Backfill Detail included on Exhibit C —Mine Plan Map submitted with the <br /> permit application indicates a liner key into competent bedrock and a perforated drain <br /> pipe surrounded by drain sand behind the keyway. The stability analysis models do not <br /> account for the keyway or drain pipe. Please explain this discrepancy and update the <br /> stability analysis models to incorporate the missing features. <br /> Response 56 <br /> A decision was made at the time the stability analyses were performed that neither a <br /> keyway into bedrock nor the existence of the drain system would significantly affect the <br /> stability analyses. This was due to two assumptions: <br /> 1. Any failure surface that would be affected by the keyway would have to pass <br /> through the competent bedrock. This is unlikely, due to the existence of the <br /> weaker alluvial materials immediately above it. <br /> 2. Drain system sand would affect a relatively small area of the stability cross- <br /> section, and the sand would have strength parameters similar to the conservatively <br /> low strength parameters assumed for the alluvium. <br /> These assumptions argue that neither the inclusion of the keyway, nor the sand drain <br /> would have a significant effect on the overall stability of the embankment. A discussion <br /> of this issue has been added to the updated Geotechnical Stability Analysis report <br /> (Attachment 7). <br /> Comment 57 <br /> Please provide the SLOPE/W slope stability analysis data from the Telesto stability <br /> analysis models to allow the Division to duplicate the analysis with Clover Technology's <br /> Galena software for verification purposes. <br /> Response 57 <br /> The stability analysis data has been included as an appendix to an updated Geotechnical <br /> Stability Analysis report (Attachment 7). <br /> Response to DRMS comments T E L E S T <br />