2016-04-06_PERMIT FILE - C1982056 (3)

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pastureland mixture. If a supply well is established, a road corridor will remain along with a 30' x 30' area for a well house and similar facilities. .It should be noted that any open hole or well will be grouted from the bottom to within three feet of the surface, as'part of the reclamation activities at the site. Northern Mine District (NMD) Power Borehole and Additional Borings (MR 00-169) TCC proposes to construct a high voltage substation (Substation 11) and power borehole drop for the development and mining of the Northern Mine District. This project will encompass the construction of 2,500 feet of new access road, a 69Kv powerline, substation, switchgear building, grounding bed and borehole into mine. Map 24 shows the proposed access road, 69KV powerline, substation, and power -drop borehole. The total disturbed area will be 200 x 200 square feet for the substation, building, and borehole. If, however, soil resistivity tests indicate that the ground -bed should be installed outside the 200 x 200 square foot area, then TCC will require an additional 30 x 30 square foot area for the substation ground -bed, as close as possible to the main substation. The new access road extending from the EMD dewatering borehole to the new power borehole will be constructed consistent with the recommendations presented in Exhibit 25R, NMD, Power Borehole Access Road. Topsoil will be removed to a depth of 2 feet and windrowed to one side or stockpiled. The salvaged topsoil will be stabilized by seeding with the topsoil stockpile stabilization seed mixture. The topsoil salvage corridor will be approximately 40 feet wide to provide for borrow of subsoil materials for road and drainage construction. As an alternative to topsoil salvage, a geotextile may be placed directly on the topsoil and gravel road base placed and compacted over the fabric overlay. The proper depth of road base will be placed and compacted as recommended in Exhibit 25R. A 2 -mile (60 powerpoles) 69KV powerline will be installed from the Foidel Creek Substation to the new power borehole, as shown on Map 24. Some of the poles to be placed along RCR No. 33 will require brush clearing or minor leveling of the route into the location to allow for safe operation of the mobile equipment used in installing •the poles. If required, the brush will be knocked down with a blade or similar type of equipment to facilitate access. In the event minor leveling is required, topsoil will be temporarily windrowed to the side, and the topsoil will be replaced and seeded once powerline construction is completed. The powerline will be constructed in accordance with the REA Bulletin 610 or equivalent to address raptor protection. The power borehole pad will require salvaging approximately 5,700 cy of topsoil and stockpiling it adjacent to the pad. The stockpiles will be placed around three sides of the pad, as shown on Map 24, and stabilized with the appropriate seed mixture. A small gap will be left in the northeast corner of the pad so that surface drainage can drain from the pad. The pad will be graded so that it drains to the northeast. At the entrance to the pad, a culvert may be placed to route upland drainage under the road and around the pad. The design of the culvert is presented in Exhibit 8.5, NMD, Power Borehole Culvert Design. The substation will consist of four powerpoles for powerline termination, three transformer pads approximately 15 x 12 feet, a 14 x 30 foot prefabricated metal building with foundation, and station ground -bed. These structures are shown on Map 24. There will be three fuse disconnects and three gang -operated disconnects between the power pole terminations and the transformers. The metal building will house the switchgear for the power -feed from the transformers to the power cables that feed into the power borehole. The station ground bed will consist of copper rods buried at 5 feet around the perimeter of the fenced substation. The power borehole will be developed by reaming out the existing 6'/a -inch borehole to a 24 -inch diameter. A raiseborer will be used to ream the hole, with all water and cuttings going into the mine. The cuttings will be stored in the previously developed rock rooms of the Northeast Mains section. Three 6 -inch diameter PVC conduits, three 2 --inch diameter PVC conduits, and a 6 -inch Schedule -80 pipe will be placed in the 24 -inch diameter hole and then the hole will be completely grouted around the annulus of the pipes. Two of the three 6 -inch PVC casings were •deformed as they were being grouted in-place, so they were re -grouted from the bottom to stabilize them in the hole. In order to hang the power cables in the holes, a steel structure will be constructed over two or three of the cased holes (the additional holes/borings are discussed in the following paragraph). MR00-169 2.05-65.2 08/01/00