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MINING AND RECLAMATION PLAN January„ 1986 <br />MT. GUNNISON N0. 1 NINE • <br />Toxic Discharge - In the event that the mine water is toxic and <br />non-dischargeable quality, permanent mine seals will be constructed. Permanent <br />seal design basis h~idraulic heads and seal locations are discussed in this <br />section. <br />Seal Design Basis - Permanent seal design is based on the assumptior~ that the <br />mine will be filled with water after mining of the F seam and that t:he hydraulic <br />head could reach about or approximately the same level as before mining tfie F <br />seam. From this as<.,umption, the maximum possible or worst case forces on the <br />seals were ealeulate~d. <br />A typical north-south profile showing the surface and F seam are given in the <br />Exhibit 3.5.2.E1. the F seam dips from three to five degrees to the north-east. <br />The elevation difference between the mine portal and south end of the mine near <br />East Fork is 1750 feet. Also the maximum possible potentiometric head profile <br />above the F seam is shown in the Exhibit 3.5.2.E1. This potentiometric head <br />based on data from water well C-76, collected over the years and is <br />approximately 250 feet. The potentiometric head of 250 feet could vary from 0 <br />to 250 feet and will depend on the amount of water in the mine after mining and <br />transmissivity in the rock layers above the F seam. <br />Based on the assumption that the mine will be completely filled with water after <br />mining and will re-establish the premising potentiometric head before mining, <br />the force on the mine seals were calculated. <br />Seal Locations - Primary main entry and Sylvester Gulch ventilation portals <br />seals will be constricted after mining of the F seam. If necessary and required <br />additional seals could be constructed in the mine as the mining retreats to the <br />north form south end of the property. The need far seals in the mine will <br />depend on the mine water levels in the old workings and the water in•F1ow rates <br />into the mine. When necessary intermediate seals in the mine could be <br />constructed under thc~ Minnesota Creek and South Prong Creek. The locations of <br />the main entry, ventilation portal seals and possible seal locations under t~ <br />Minnesota Creek and.~outh Prong Creek are shown in the Exhibit 3.5.2..E2 and iiT <br />Exhibit 3.4.4.6.1. <br />3-82 <br />