2013-11-27_REVISION - M1990057 - Laserfiche WebLink

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Mr. Michael Cunningham CDRMS November 26, 2013 Response: 20 The TSF is small and located directly adjacent the mill facility. It is UMC's opinion that ongoing activity will deter wildlife and that no specific measures are required to keep wildlife from coming into contact with the TSF. 43. Please specify how much buffering material (hydrated lime) would be required to neutralize all of the fluids in the mill circuits. The Division will require to Operator to have an adequate amount of buffering material present at the mill at all times so that the mill circuits can be totally drained and buffered in the event of permit revocation and bond forfeiture. Response: Metallurgical test work performed at RDi Laboratory (Wheat Ridge, CO) on representative samples of Cross Mine (Boulder County, CO) indicated that 3.4kg of Lime (Ca(OH)2) per tonne of ore would be required to neutralize the material to a pH of about 9.0. This converts to approximately 6.4lbs -lime /ton -RoM. For the purpose of estimating reclamation requirements, UMC has doubled this requirement to 13.6lbs -lime /ton -RoM. Given a maximum 135 -tons of RoM that can be in the system and which is not neutralized, approximately 1 ton of lime will be required. Water is essentially the only fluid in the system and does not require neutralization. Reagents account for a small fraction of fluids, are generally neutral by nature, and also will not require neutralization. UMC commits to keeping 1 ton of lime (see Exhibit C, Table 4 -5 in Permit Application) at site at all times. Further, we have included the cost of purchasing 1 ton of lime in the mill reclamation cost estimate (Appendix 5 -1 in Permit Application, and Attachment 6 in this letter). 44. The Applicant has stated the current capacity of the TSF will allow the mill to operate up to one year. It has been the direct experience of the Division that sites that go into bond forfeiture are frequently subject to disorderly termination by Operators. The Division must assume that under a 'worst case scenario' the ore bunkers, coarse ore bin and fine ore bin will be at full capacity. Therefore, the Operator will be required to halt milling activities when the TSF reaches 80% capacity to allow for running all remaining ore through the mill and to provide the 120% capacity to for all mill fluids in the event of complete failure. Please respond. Response: UMC disagrees with this comment due to the small size of our facility. Given planned operating parameters, our worst case scenario in- process material would amount to approximately 170yd3. This value includes; 135 tons (35 course ore plus 100 tons fine ore) or 100yd3 solid material plus 14,OOOgal or 70yd3 of slurry (see Table 4 -6 in question 13). Note that fresh process water and domestic water totaling 10,500gal is not included in the slurry value. Both raw process water and domestic water have no contact with processing and therefore would report to the domestic sewer system.