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Ouray Silver Mines, Inc. 1900 Main St. Unit i PO Box 564 Ouray, CO 81427 ta-'RAY S/L L ER lVrtllVE July 29th, 2021 RECEIVED Colorado Division of Reclamation Mining and Safety AUG 06 2021 1313 Sherman Street, Rm 215 DIVISION OF RECLAMATION Denver, CO 80203 MINING&SAFETY Subject: Technical Revision 15 (TR-15) Mill Commissioning Using Day Tanks DRMS Permit No. M-2012-032 Revenue Mine, Ouray County, Colorado Dear Mr. West, Ouray Silver Mines, Inc. (OSMI) is formally requesting permission to begin commissioning the Revenue Mill using day tanks in the Mill Tunnel in order to avoid delays to the mill startup and commissioning schedule. While the Reagent Room of the Revenue Mill is being constructed, OSMI proposes to mix reagent chemicals off site and transport them to the mill's day tanks for use in the commissioning process. Except for lime, the reagent chemicals will be mixed in 240- gallon totes in the mine's warehouse in the city of Ouray and then brought to the mill for use. Lime will be transported as a solid and added directly to the mill process. The reagents would be brought to site after the mill system has been pressure/leak tested and just before ore is added to the mill circuit. Reagents mixed off site would need to be taken to site a maximum of two times before the completion of the Reagent Room. A single 240- gallon tote contains sufficient reagents for roughly one month of processing. Sodium metabisulfite is consumed at a slightly faster rate than other reagents and two totes of this reagent might be used before the Reagent Room is complete. The 240-gallon totes containing mixed reagents would be mixed off site, transported to site, unloaded from the transport vehicle, staged in the Mill Tunnel and a transfer pump would be used to move reagents from the totes into the day tanks. Reagents would be applied at the same dosing rates as proposed in Technical Revision#15. All environmental controls for the Mill Tunnel are in place. A copy of current red-lined drawings for the Mill Tunnel are attached to this letter. Modifications to the drawings have been highlighted. Please note that these drawings will change as modifications to the mill circuit are made during the commissioning process. As final set of as-built drawings will be submitted to the Division upon completion of mill commissioning. OSMI appreciates your attention to this matter. If you have any questions, please contact me at (970) 325-9830. Phone: (970)325-9830 ♦ Fax: (970)325-9824