Laserfiche WebLink
Cross Gold Mine <br />December 2024 E-6 <br /> <br /> <br />revegetation and erosion control is 25 x 25 feet. The shaft closure will be fenced with a 5x5 foot chain <br />link fence and will be posted for hazard and trespass. <br /> Cross Ventilation Shaft <br />The Cross Ventilation Shaft will use the concrete panel closure shown in Figure 2 of Appendix E-1. The <br />panels will be 3 by 3 feet, with 1 foot thickness, wire and/or rebar reinforced, and will be secured with <br />bolted panel footings. The Cross Ventilation Shaft closure will use 6 panels (2x3 array), and one 8-foot <br />support beam fixed with concrete in accordance with the detail in Figure 2 of Appendix E-1. Panel and <br />beam concrete will have a minimum compressive strength of 3,000 psi. A grated access door will not <br />be used in the concrete panels because the closure will be recontoured. <br />Following construction of the concrete panel closure, the hillside contour at the Cross Ventilation Shaft <br />will be restored to approximate original contour by burying the panels. Material left over from historic <br />shaft construction will be used. The estimated disturbance area requiring revegetation and erosion <br />control is 25 x 25 feet. The shaft closure will be fenced with a 5x5 foot chain link fence and will be <br />posted for hazard and trespass. <br /> Caribou 300 Level Portal <br />The Caribou 300 Level portal closure is estimated to be 8 x 8 feet in vertical and horizontal dimensions. <br />The portal will be closed using a concrete block closure as shown on Figure 1 of Appendix E-1. <br />Concrete blocks will be 8x8x16. Because the portal is dry a drainage pipe will not be necessary. <br />Additionally, a grated access door will not be used in the block wall because the closure will be <br />recontoured. Following construction of the concrete block wall closure, the hillside contour will be <br />restored to approximate original contour using materials within the permit area left from historic portal <br />construction and use. The snowshed and fencing will be removed prior to closure and the materials <br />recycled or disposed of according to Section 1.1. <br />The estimated disturbance area requiring revegetation and erosion control is the dimension of the <br />disturbance area (75 by 190 feet). <br /> <br />All surface water diversion structures will also remain in place to reduce stormwater that passes over <br />the reclamation area to reduce erosion. These structures will be allowed to organically decay and fail <br />following final reclamation. All diversion structures will be seeded with the mix identified in Table E-4. <br />The mine water treatment piping will be left in place and connected to the drainpipes on both the Idaho <br />Tunnel and Cross Mine Adit bulkheads. The buried pipes will facilitate the discharge of the minewater <br />into Coon Track Creek at the same discharge point as during mining. The buried pipes mean debris will <br />not be able to enter the piping network. The pipe network and bulkhead connections are shown on Map <br />F-1. <br /> <br />Surfaces for revegetation will be roughed to gain a mechanical bond between the subgrade and the <br />replaced topsoil. Where the subgrade is of acceptable quality, it may include disc plowing the topsoil