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16. Page 5-10, Section 5.3.4 Mine Area Stability <br /> • The last sentence indicates there have been no "observable slope failures other than <br /> occasional bench raveling." The Division is aware of the movement/slope failure in the <br /> south end of the WHEX that caused the mine to relocate the previously planned adit in <br /> the WHEX. Please explain why this is not considered an observable slope failure. <br /> RESPONSE:Periodic bench scale failures have occurred on the south end of the WHEX <br /> Pit and have been cleaned. In addition, a regressive (self-buttressing) slope instability is <br /> being managed as a single bench mining zone with a 30'inter-ramp slope angle due to <br /> the nature of the geologic structure in that area. The slope is currently monitored 24 <br /> hours/day by CCV geotechnical staff with a combination of prism monuments and <br /> extensometers. Due to the relatively shallow angle of the existing slope (approx. 27 <br /> degrees), there is minimal risk for rock fall or slope runout. The slope poses no risk to <br /> the public or critical structures. <br /> 17. Page 5-15, Section 5.4.3 Underground Hauling and Mucking <br /> • The last sentence indicates development rock may be temporarily store on the surface <br /> prior to being hauled to an existing overburden storage area. Please indicate where the <br /> temporary storage will be, how long is temporary and how the potential for acid rock <br /> drainage will be controlled in these temporary storage location(s). <br /> RESPONSE. There is an existing pad located outside the Chicago Tunnel portal that <br /> has been constructed to stage development rock mined from underground. In addition, <br /> CC&V has developed preliminary designs to construct a lined development rock storage <br /> pad, which will control the potential for acid rock drainage (see preliminary schematic <br /> provided in Attachment 5). Storage time will be dictated by the limited available storage <br /> space at the portal. It is anticipated that the development rock not used as backfill <br /> underground will be staged at the portal for a period less than 7 days until there is <br /> enough volume to haul to an existing overburden storage area. <br /> 18. Page 5-15, Section 5.4.4 Schedule <br /> • The second paragraph references a planned raise bore to allow sufficient ventilation for <br /> stope mining. Please indicate where the raise bore is expected to daylight on a map <br /> (Note: This may be the same issues discussed in Comments 8 and 9 above for Drawings <br /> C-5a and C-5b). <br /> RESPONSE:See response to Comment 8 and 9 above and please see revised Drawings <br /> C-5a and C-5b. <br /> 19. Pages 5-17 to 5-18, Section 5.6.2 East Cresson Overburden Storagea <br /> • The paragraph under the "General" subsection indicates MLE2/AM10 extended the <br /> ECOSA to approximately 274 acres. The second paragraph under the "Construction" <br /> subsection(p. 5-18) suggests the ECOSA footprint nearly doubles in size to 500 acres. <br /> Please explain the apparent discrepancy in the ECOSA footprint. <br /> RESPONSE: The proposed Amendment 11 does not increase the footprint of ECOSA as <br /> it relates to new disturbance in the direction of Grassy Valley. Rather, as the height of <br /> ECOSA is increased, additional overburden will be placed on the backside of the OSA <br /> covering previously disturbed areas. <br /> Page 9 of 30 <br />