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<br /> <br />Based upon the results of the hydrogeologic analysis presented in <br />• Appendix E-2, Cotter Corporation will seal the Steve adit and vent adit <br />on the Steve level with gunite seals placed approximately three hundred <br />fifty feet from the number 2 shaft toward the entrance of the adits. <br />The gunite seal method involves the use of pneumatically-pla,~ed lour <br />slump concrete that rapidly and effectively seals mine openings. The <br />roof, sides and floor of the area selected for placement of 'the seal <br />will be shaped so that the space will be a form for a tapered gunite <br />plug. A wood bulkhead will be constructed at the inner limit of the <br />seal in order to support the initial placement of gunite. Tne gunite <br />will be projected by an air jet directly into place and will stand <br />vertically, thereby eliminating the need for forms. The seal will be <br />constructed by placing successive thin layers of gunite. It should <br />be noted that a seal constructed by this method completely fills the <br />• opening in which it is placed and provides a particularly efFective <br />seal against higher hydraulic heads. The hydraulic head anticipated <br />at these two seals will be on the order of 10-15 pounds per sgaure <br />inch (psi). The U.S. Environmental Protection has indicated that this <br />particular mine seal method shows promise of being an excellent under- <br />ground mine seal. <br />Also, all of the remaining adits shown on Exhibit C, will be sealed in a <br />manner that will prevent unauthorized entry into the mine workings. <br />It would appear that an effective method in this regard will be the <br />use of the dry seal process. The dry seal will be established by <br />constructing a masonary block bulkhead on a concrete footing across <br />the entire adit opening. <br /> <br />E-4 <br />