2021-12-07_REVISION - M2012032 (25)

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3.1 Drifts and Tunnels Accessible drifts and tunnels at the Revenue were driven on roughly 0.5%uphill grade from the portal over 100 years ago and are 8' x 8' in size with a 24-inch-wide set of 40 lb rail on the left side of the opening and a drainage ditch on the right side. The main Revenue tunnel was driven primarily through the San Juan Formation host rock to access several veins. This drift is approximately 7,900 feet long and accesses the Yellow Rose vein,the Atlas/Cumberland Vein, Terrible Vein, Montana Vein,and the Virginius Vein, as well as a few minor veins. The main Revenue tunnel basically ends at the Virginius Vein. The main Virginius shaft is located near the terminus of the Revenue drift. This shaft extends up to the surface at an elevation 12,900 feet. Power cable,phone lines, compressed air line and ventilation piping is attached over the center of the track or over the drainage ditch using a messenger cable that is pinned to the back or ribs with steel I-bolts. The track is secured to 6"x 8"wood ties on 5' centers with additional support in the form of steel ties every 10 feet. Between the ties and the ditch,the sill is filled with ballast material (broken waste rock)to stabilize the track. Most of the openings are created using handheld rock drills (air powered)to drill a pattern of holes that are then loaded with explosives and detonated to break the solid rock into manageable size pieces. The broken rock is then picked up with air powered mucking machines and loaded into mine cars and hauled outside with electric locomotives where it is placed on the Temporary Waste Rock Pile. This type of development work is done in host rock that contains little or no mineralization. If a drift or opening is driven on a vein or structure,the material is sampled at close spacing and assayed for elements that may contain value,mainly gold, silver, lead, copper and zinc. If it is determined that the broken material contains value,it is diverted to the mill for processing. 3.2 Raises Raises are vertical tunnels used to access the blocks of ore in the vein. Most of the raises in this mine were created either as "bald headed"or using an air powered Alimak climber and air powered drills. Once the opening is completed it is typically lined with rough cut timbers secured to the walls and ladders are installed so personnel can move up and down from level to level. In the larger opening there is usually an electric powered hoist with a cage (elevator)to move personnel and equipment. Some raises may be installed via raise boring. In this method a powerful drill machine bores a hole from an upper elevation (or the surface)to an appointed location where there is a large cutter head (4' — 8') attached to the rods,it is then pulled back up to the starting point whilst reaming the opening to the desired diameter. The opening is then fitted with steel ladders and landings. A hoist is installed and used to move personnel and materials up and down. Excavations in the Revenue Mine will be built using methods similar to those described above. General equipment used in the mine are slushers (air or electric)to move broken rock into loading chutes,tuggers (air or electric)to hoist or lower personnel or supplies and diamond drills (air or electric)to drill exploratory holes to test for the location and value of a vein. A list of mining equipment is provided in Table D-1. 1ALUMINUMNOM Underground Equipment Number Locomotives 1.5 Ton Goodman Manchi 3 4 Ton Goodman Loci 3 4 Ton Atlas Loci 1 4 Ton Greensburg Loci 2 Revenue Mine Amendment 02 D-4 December 2021