2011-09-28_PERMIT FILE - C1982056A (10)

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Site - specific investigations required for design and permitting of the new utility borehole installation include a cultural resource survey and wildlife consultation. The cultural resource survey results are summarized by the survey report provided in Exhibit 6T, and a wildlife consultation letter is included in Exhibit 23C. The perimeter of all areas to be disturbed will be clearly marked and construction drainage control measures (silt fences or wattles) • will be in place prior to disturbance. In order to reestablish effective vegetative cover during site reclamation, TC will recover and stockpile a maximum of 1.0 foot of soil material from the road and pad disturbance areas. A maximum of approximately 7,300 cy of soil will be recovered and stockpiled- from the road disturbance area, and approximately 3,600 cy from the pad area. Natural vegetative materials incorporated into the salvaged soil materials and seeding with the soil stockpile stabilization seed mixture will assist in stabilizing the stockpiled soil material and preventing erosion or loss of soil material. Following soil recovery, appropriate designed drainage and sediment control structures will be constructed or installed. A total of six culverts (each approximately 30 feet long) will be installed along the light -use road to pass natural drainage under the road, and the road surface will be graveled to provide all- weather access and control runoff and sediment generation. The two culverts south of the 17 -Left Pad and the culvert adjacent to the 16 -Left Pad are designed culverts, while the remaining culverts have limited contributing drainage areas, address road drainage only, and are significantly oversized (all culverts are 30 -inch diameter CMP). The proposed pad location is on the side of a small knoll, so upgradient drainage will be limited. The limited amount of drainage from upgradient areas will be intercepted and routed around the borehole pad by a small designed upgradient diversion ditch along the west and north sides of the pad. Drainage from the small borehole pad will be controlled under a Small -Area Exemption by gravel surfacing on the pad surface, temporary revegetation seeding of pad cut /fill slopes, and by small interceptor ditch along the south and east sides of the pad, (size the same as the diversion ditch, although the drainage area is significantly smaller) draining through a rock sediment basin to the adjacent natural drainage. Road construction will involve soil recovery, placement of culverts, scarification and recompaction of surface materials, necessary cut /fill work to establish the road profile, and placement and compaction of approximately 3 inches of suitable roadbase materials and 8 inches of pit -run gravel. It is anticipated that two to three turn -outs (up •to 30 -foot wide) will be constructed in flat straight areas along the road to allow passing of heavy trucks. The 24- foot road surface will be graded and crowned to promote effective drainage. Construction of the borehole pad will involve soil recovery, installation of drainage structures, cut /fill pad construction, and placement of gravel surfacing material to control dust and sediment from the pad area. Borehole completion will involve drilling, installing, and grouting a 20 -inch diameter steel surface casing in place to a depth of up to 80 feet (dependent on the ground conditions encountered). The borehole will then be advanced, using directional drilling, to a depth of approximately 1,700 feet to intercept the mine workings. Water, drilling fluids, and cuttings will be contained within one or more portable steel tanks (porta -pits) on the borehole pad. The borehole will be drilled to a nominal diameter of 17 inches, and three welded steel carrier pipes, one 6.625, and two 2.375 inches in diameter, will be suspended in the borehole and grouted in. A collar for pumping concrete or portable fabricated steel chute will be fitted to the larger carrier pipe for concrete and material drops. Concrete or other materials will be transferred underground using a pipeline or underground equipment to the location(s) where they will be used. The 16LT Utility Borehole installation will remain in -place until it is no longer needed to support ongoing or anticipated future mining operations. Reclamation of this installation will involve plugging and sealing the borehole, regrading the pad and road areas to their approximate original configuration, soil material replacement, and reseeding with TC's standard Pastureland Seed Mixture, or an alternate seed mix, if requested by the surface landowner. 15 -Left Ventilation Shaft (TR11-77) As a result of progressive mine development in the Western Mining District (WMD) and expanded MSHA rock- dusting requirements, a new ventilation bleeder shaft and additional rock -dust transfer location will be needed to support ongoing mining operations. The proposed new ventilation shaft will be located off the existing light -use road serving the Fish Creek Water Treatment Facility in the SW' /SE' /o Section 24, T5N, R87W, as shown on Map 24. Development, construction, and installation of the ventilation shaft and associated ancillary facilities will TR11 -78 2.05-45.22 09/15/11