2011-03-01_REVISION - M1977493 (6)

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Mr. Eric Scott Climax Mine - Response to DRMS Adequacy Review Comments . Permit M-1977-493; Amendment AM-06 March 1, 2011 Page 3 of 16 Response: Mining operations at the Climax Mine will utilize explosives to fragment overburden and ore. The blasting program will utilize standard drilling and blasting techniques, with blast rounds managed so they are detonated on a single hole per delay basis using a minimum of an 8- millisecond delay between holes. The blasting program will follow the US DOI, Office of Surface Mining Reclamation and Enforcement Blasting Guidance Manual protocols. CIVIC would like to clarify that the DRMS Rules, both in Hard Rock/Metal Mining Rules (HRMMR) 6.4.4(i) and 6.5(4), are directed at the impact of blasting on off-site areas. The OSM guidance and the underlying codified regulations (30 CFR 816.67) identify structures of concern, related to maximum peak velocity, as any dwelling, public building, school, church, or community or institutional building outside the permit area. There are no such structures, not considering the on-site mine and mill buildings owned by Climax, within several miles of the mine. The nearest non-Climax owned structure of any kind, as identified on Figure AM-06-C-01, is the Xcel substation near the entrance to the mine site. This structure is approximately 2,600 feet from the edge of the pit. Although this structure/facility is not an occupied structure and therefore may not technically fall under the OSM criteria we are considering this location in this demonstration of no adverse affect. The OSM guidance provides for the use of a scaled distance equation to determine the allowable . charge weight of explosives to be detonated within any 8-millisecond period, without seismic monitoring. This formula is W = (D/Ds)z ; where W = the maximum weight of explosives in pounds; D = the distance, in feet, from the blasting site to the nearest protected structure; and Ds = the scaled distance factor. For distances between 301 and 5,000 feet the guidance suggests the use of a Ds of 55, which relates to a maximum allowable peak particle velocity for ground vibration of 1.00 inches/second. It is our understanding that this criterion is established as a conservative level to protect plaster and drywall from cracking in occupied structures in response to ground vibration. Applying the Ds of 55 at a distance of 2,600 feet results in a maximum weight of explosives per 8- millisecond detonation of 2,235 pounds of explosive. The Climax mine plan is currently contemplating maximum blast rounds on the order of 700 to 850 pounds, well below this limit. As stated previously, the HRMMR do not require a demonstration of stability related to blasting for any on-site feature or structure. However, because of the distance from the pit to other on-site features and the conservative nature of the scaled-distance evaluation, CIVIC believes the evaluation presented above adequately demonstrates that these features will not be adversely affected by blasting. Exhibit E - Reclamation Plan Exhibit E Comment: It appears that no permanent up-gradient clean water diversions will be constructed around the OSF locations. If this is intentional, please justify. If this was an oversight, . please add these diversions to the appropriate figures and water management diagrams. Otherwise, Exhibit E is adequate as submitted.