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Henderson 2000—PC3 OveMd Surface Conveyor 0 <br /> Technical Revision #7 to Permit M-77-342 Page 7 <br /> . of 4-6 inch durable rock at this location (par. 4). This letter also details the stabilization work <br /> accomplished by Henderson at this specific site. A copy of this letter is included as Appendix E. <br /> 3.4 Use of Shot-crete <br /> Shot-crete is a concrete mixture that is applied by a spray system to stabilize steep rock walls and <br /> slopes or other areas of unstable rock. Shot-crete systems are used extensively in underground <br /> mines and in tunneling operations both in place of and in conjunction with conventional rock <br /> bolts and screening. The use of shot-crete for such stabilization was not incorporated into the <br /> approved amendment, but nevertheless, may have application to construction of the overland <br /> conveyor system. Therefore, Henderson is proposing to add this method of stabilization to the <br /> amended permit through this TR even though it may not be used. <br /> Henderson investigated using shot-crete on the steep cut on the hill south of the Con-6 wetland <br /> (Station 124+2.00) as discussed in the August 13, 1998 DMG inspection report, but determined <br /> • that this method of stabilization wasn't necessary. In addition, the U.S. Forest Service expressed <br /> reservations regarding the long-term use of this material for slope stabilization. Cutting the slope <br /> one-half length and buttressing with a bench on which the conveyor struts were emplaced <br /> stabilized the slope in question. The slope and area were seeded and will be maintained in a <br /> revegetated state rather than using shot-crete. However, Henderson wishes to have shot-Crete <br /> added to the permit should its use be determined as feasible or necessary. <br /> N:/255rMO7/TR7.doe <br />