2024-04-25_PERMIT FILE - C1982056A (3)

Home Browse Search

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 & Additional Borings (MR 00-169, TR00-37) TCC proposes to construct a high voltage substation 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, 69 KV power line, substation, switchgear building, grounding bed and borehole into mine. Map 24 shows the proposed access road, 69 KV power line, substation, and power borehole. The total disturbed area will be 200 x 200 square feet for the substation, building, and borehole. However, if soil resistivity tests indicate that the ground bed 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 as per the recommendations presented in Exhibit 25R, NMD, Power Borehole Access Road. The topsoil will be removed to a depth of 2 feet and windrowed to one side or stockpiled. The salvaged topsoil will be stabilized with the topsoil stockpile stabilization seed mixture. The salvaged topsoil corridor will be approximately 40 feet wide to allow "borrowing" of sub -soils to bring the road back up to grade to facilitate drainage. As an alternative to the topsoil salvage procedure described above, a geo-textile may be placed directly on the topsoil and the gravel placed and compacted onto of the fabric. The proper depth of gravel will be placed and compacted as recommended in Exhibit 25R. A 2 -mile long 69 KV powerline will be installed from the Twentymile mine entrance area to the new power borehole as shown on Map 24. The line will consist of approximately 60 wooden pole sets and the necessary cross - frames. 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 this is required the brush will be knocked down with a blade or similar type of equipment to facilitate entry into the location. In the event minor leveling is required the topsoil will be windrowed to the side, the location accessed by the mobile equipment and then the topsoil pulled back in after the pole is installed. The powerline will be constructed in accordance with the REA Bulletin 610 or equivalent. The power borehole pad will require salvaging approximately 5,738 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. The topsoil stockpiles will be 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 power -poles for powerline termination, three transformer pads approximately 15 feet x 12 feet, a 14 foot 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 '/4" borehole to a 24" diameter to a depth of approximately 1,350 feet. The reaming process will be a raise -bore 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" diameter PVC conduits, three 2" diameter PVC conduits, and a 6" schedule 80 pipe will be placed in the 24" diameter hole and then the hole completely grouted. Two of the three 6" PVC casings were deformed as they were being grouted in-place, and they will be grouted from the bottom to the top to stabilize them in the hole. In order to hang the power cable in the hole, a steel structure will be constructed over two or three of the cased holes. (The additional holes/borings are discussed in the following paragraph.) RN 17-07 2.05-65.2 02/15/18