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<br />15. Ventilation Shafts <br />Each ventilation shaft permit azea is 100 feet x 100 feet in size, or 0.23 acres. A concrete pad up to <br />200 squaze feet in size and a thickness of 6" will be constructed at each new vent shaft to provide a <br />level platform for drilling equipment during installation. Prior to installation of the pad, topsoil will <br />be stripped to a minimum depth of 12 inches and the material will be stockpiled at the perimeter of <br />the pad for later use in reclamation. This was also isolate the pads from surrounding drainage. All <br />drainage from the pad azea will be kept on site by the berm. These small piles will be seeded and <br />mulched since they will be present for a number of years. The pad maybe constructed in the form <br />of a donut where the central azea is left open for the shaft. The ventilation shaft opening will be up <br />to 6 feet in diameter. The hole will be cased and grouted as necessary to prevent any water from the <br />upper aquifers from entering the mine workings. Once the shafts are completed and cased, asingle- <br />vane axial fan with a diffuser will be mounted on top of each hole. These units aze typically about <br />three to five feet high and have metal grates on top. Taller diffusers maybe installed if additional <br />noise reduction is required. The diffusers will be painted a light tan color to blend in with the <br />• surroundings. The fans will be powered by electricity from nearby power poles and each unit will <br />have locked breaker boxes at the power drop. <br />As previously stated, there is one existing shaft in Colorado, called the Ten Straight Shaft. One <br />additional shaft maybe installed, called Shaft C-1. Also, up to 6 shafts maybe installed in Utah. <br />See Map C-1 B for the locations of all of these shafts. <br />16. Surface Drainage Control Structures <br />Surface drainage control is divided into the following three main categories: <br />1. Surface drainage from undisturbed areas uphill from both portal areas will be permanently <br />diverted azound the mine area via constructed ditches and culverts. This water will be diverted <br />directly to nearby natural drainages. All such diversion ditches and culverts are designed for the <br />NOAA yeaz round 100-yeaz, 24-hour storm event of 2.9 inches. This is more conservative than the <br />L~ <br />Whirlwind Mine July 07 D-24 <br />