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Additional details of the three ventilation phases are provided below. <br />3.3.1 Phase I Ventilation System <br />Currently, the Whirlwind mine consists of a 3,200-foot-long decline and approximately <br />700 feet of developmental drift in the ore zone as shown on Figure 3, Existing Mine <br />Workings. To ventilate the decline, approximately 40,000 cfm of air is mechanically <br />induced using two sets of staged intake fans. Fresh air from each fan set is carried in 30- <br />inch diameter steel vent pipes for approximately 3,500 feet. Because of friction losses in <br />the pipe, high pressure is necessary to move the air. Figure 4 shows how the air <br />ventilation system is currently configured with fresh air directed to both the west and <br />south working faces. <br />Figure 5 illustrates how the drifts will be ventilated until such time that they can be <br />connected to the Packrat Mine workings to the north and the proposed C1 vent shaft to <br />the south. This mining will include development of the "A" ore zone and development of <br />the "B" ore zone. The "A" ore zone is located between the Whirlwind decline and the <br />Packrat Mine. The "B" ore zone is located to the south and west of the Whirlwind <br />decline. Development to both locations will occur simultaneously. Booster fans, vent <br />bag (i.e., collapsible vent tubing), and brattice curtains will be utilized to direct air into <br />individual work areas. <br />i It is estimated that the Phase I ventilation system will be in place for 4 to 6 months before <br />mining will advance to the point where the Phase II ventilation system can be established. <br />The use of vent pipe or tubing is not suitable for moving large quantities of air and is <br />costly with regard to power consumption. To avoid this situation, the Phase II ventilation <br />plans are designed to provide primary ventilation through exhaust fans mounted directly <br />in bulkheads near exhaust openings. <br />3.3.2 Phase II Ventilation System <br />Phase II of the ventilation plan, shown on Figure 6, includes stoping of the A and B ore <br />zones and further mine development. The 700-foot-long main ventilation drift from the <br />lower end of the Whirlwind Mine to the Packrat Mine will complete an exhaust circuit <br />between the Whirlwind portal and the Packrat portal. It will also establish a secondary <br />escape way, which is required by MSHA before commencement of further mine <br />production operations. A ventilation circuit will also be completed through the "B" ore <br />zone by installing a vertical exhaust shaft to the surface (C 1). <br />8