2010-08-23_REVISION - M1979181 - Laserfiche WebLink

Home Browse Search

STATE OF COLORADO DIVISION OF RECLAMATION, MINING AND SAFETY Department of Natural Resources 1313 Sherman St., Room 215 Denver, Colorado 80203 Phone: (303) 866-3567 FAX: (303) 832-8106 August 20, 2010 Karmen King Grayling LLC 18050 Rd. G Cortez, CO 81321 COLORADO D I V IS I ON OF RECLAMATION MINING SAFETY RECEIVED Bill Ritter, Jr. AUG 2 3 20110 Governor James B. Martin Division of Kutac:u,sation Executive Director , Unin9 and Safety Loretta E. Pineda Director Re: Ruby Trust Mine, Permit No. M-1979-181, Amendment AM-1, Second Adequacy Review Letter. Dear Ms. King, On August 11, 2010, the Division of Reclamation, Mining and Safety received the adequacy responses that addressed the Division's adequacy review letter, dated June 28, 2010, for the permit amendment named above. The decision date for the amendment application was extended to August 23, 2010. Technical review of the amendment adequacy responses has revealed a few items that must still be addressed before it can be considered adequate for approval. All issues that still remain to be addressed are included in the list below. Please respond to each of the following items. Exhibit C - Mining Plan (Rule 6.3.3) There will be a significant amount of waste rock generated during mine development, and you have provided a map and description of the temporary stockpile locations. Due to the limited storage capacity on the permit area, however, only about 30-days' worth of waste rock can be stored there. You provided a copy of a new agreement with Ouray County Road and Bridge, to provide them with clean waste rock on a regular basis. That agreement does not obligate the county to take or receive the waste rock, so if the waste rock storage capacity is reached, the operation could conceivably have to cease temporarily. All waste rock to be removed from the site will tested and found inert, according to your plan. The waste rock is not approved to be removed from the site under any conditions other than for county use, or stockpiled in county-designated and approved stockpile locations. Please state that you acknowledge these facts. The proposed snow shed structure drawings appear adequate, though the Division did not perform an engineering analysis. The snow shed appears to require a county building permit, however, and a part of that requires an engineering certification. Please forward a copy of the permit to the Division when it is obtained, so that we can document the local government approval for it. If at all possible, please provide documentation of any local government approval to allow the snow shed to remain as a permanent structure. This will ultimately affect the reclamation bond amount. (Providing these items does not impact the adequacy or the decision date.) The underground repository of the milled, sub-grade ore (hereinafter called "tailings") is described as a fairly dry, non- mineralized crosscut, driven on a slight incline. The tailings will be slurried to the far end of the crosscut, and filled from back to front. As they passively dewater, the water will flow to the impermeable bulkhead liner, otherwise considered to be a coffer dam, where it will be collected and pumped back to the mill. Such collection requires that the geotextile liner be flexible enough to conform to the ribs and floor of the crosscut and that those surfaces are conducive to obtaining an adequate seal. Additionally, as water collects, its weight will increasingly press upon the liner. It is imperative that the wooden bracing be structurally adequate to withstand the pressure, that the liner be adequately anchored to the bracing, in the event that the volume is not monitored or pumped down. Please describe the method(s) of anchoring and sealing the liner and bulkhead bracing. If possible, please provide the name(s) and specs of the proposed liner material(s). Office of Office of Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines