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MINING AND RECLAMATION PLAN <br />MT. GUNNISON N0. 1 MINE <br />• 3.5.2 Portals and Entries <br />January, 1986 <br />Temporary Abandonment - In the event that the mine entry must be rendered <br />temporarily inactive, the opening shall be protected by barricades or other <br />covering devices, fenced, and posted with signs identifying the nature of the <br />hazard. The fences, barricades, and signs shall be periodically inspected and <br />maintained in good operating condition until mining activities or monitoring <br />work are resumed. <br />Permanent Abandonment - Upon permanent abandonment, the mine will be permanently <br />sealed to prevent access to the mine workings by people, livestock, wildlife, <br />machinery, and to keep acid or other toxic drainage from entering ground or <br />surface waters. <br />It is anticipated, based on water quality data in this Mining and Reclamation <br />Plan, that the mine drainage will be of dischargeable quality. In this <br />instance, the entries will be sealed in a manner to allow drainage through the <br />• seal and prevent the water from building up behind the seal. Should the <br />drainage prove to be toxic, an alternative sealing plan is presented and has <br />been designed to prevent the drainage from infiltrating ground or surface <br />waters. In either event, the first few courses of tunnel liner plate and steel <br />ribs, as well as the concrete structures, will be removed and the surface <br />regraded in accordance with Section 4.3 of this Mining and Reclamation Plan. <br />Non-Toxic Discharge - In the event that the drainage is non-toxic, a concrete <br />wall 8 to 12 inches thick will be constructed in each main entry in solid coal <br />just inby the portal tunnels (Exhibits 3.5.2.A, B, and C) and ventilation <br />entries (Exhibit 3.5.2D). The entries will be timbered on each side of the wall <br />to prevent excessive loads from bearing upon the concrete wall. The entries and <br />portal tunnels will be backfilled with dirt from the wall out to the surface. <br />Drain pipes comprised of 4 inch diameter schedule 40 PVC pipe will be installed <br />through the concrete wall and backfilled to allow drainage through the seal. <br />The design is based on a U. S. Environmental Protection Agency publication <br />entitled Inactive 8 Abandoned Underground Mines, Water Pollution Prevention and <br />Control. As mentioned above, the first few courses of linear plate and steel <br />ribs and the concrete portal structures will be removed and the surface <br />recontoured. <br />3-81 <br />