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utilizing small rock -lined sediment traps to control discharge and sediment. Drainage from the borehole pad area <br />will be controlled under a Small -Area Exemption, with gravel surfacing on the pad and road to control runoff and <br />sediment, stabilization of cut/fill areas with temporary revegetation seeding, and control of runoff from outslope <br />areas by the perimeter ditch and sediment traps. Drainage designs for the culverts and diversion ditch are provided <br />in Exhibit EX49EE. <br />Borehole completion will involve drilling, installing, and grouting steel surface casing in place to a maximum depth <br />of approximately 60 feet (dependent on the ground conditions encountered). The boreholes will then be advanced, <br />to depth to intercept the Wolf Creek mine workings. Water, drilling fluids, and cuttings will be contained within <br />one or more excavated pits or portable steel tanks (porta-pits) on the borehole pad. The surface casing for the larger <br />utility borehole will be 32 -inches in diameter. If dry, this borehole will be drilled to 22 -inches and cased to 16 - <br />inches, or if wet, 30 -inches and cased to 24 -inches. The surface casing for the smaller utility borehole will be 24 - <br />inches. The smaller utility borehole will be drilled to 22 -inches and cased to 16 -inches if wet. If dry, this borehole <br />will be drilled to 13.75 -inches. A 6.675 -inch and 3.5 -inch carver pipe will be placed and grouted in either the 16 - <br />inch casing (wet) or 13.75 inch (dry) borehole. The larger carrier pipe may be used for grouting, material transfer, <br />or other utility needs. The smaller carrier pipe may be used as a power drop or for a communications line(s). <br />Power to the 9 -East Utility Borehole Installation will be provided by a branch -line from the existing nearby <br />powerline, extending from 990 to 1,700 feet, depending on which pad location is selected. Powerline construction <br />will require placement of from 14 to 34 power -poles, dependent on which pad location is selected and power -pole <br />spacing (50 to 75 feet). A switch and transformer on the Yampa valley Electric line at the connection with the <br />branch -line, and a drop -line at the pad location will provide power to the portable skid -mounted exhauster units. <br />The 9 -East Utility Borehole Installation will remain in place until it is no longer needed to support ongoing <br />operations (estimated life of approximately 3 -years), and will then be reclaimed. Reclamation will involve <br />plugging and sealing the boreholes, removing the powerline, regrading the pad and road, drainage reestablishment, <br />soil material replacement, and reseeding. <br />MR16-296 2.05-45.31 05/10/16 <br />