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The proposed borehole will be accessed from the paved County Road (RCR27), using an existing established ranch <br />access (Camilletti Road) and existing ranch roads to within less than 0.25 mile of the borehole location. Drilling is <br />planned for late summer, and the remaining distance to the borehole is along a ridgeline, so no additional road <br />construction is planned, as shown on Map 24 and in Exhibit 53. The proposed Emergency Air Borehole will not <br />require any new road construction, however, a new borehole pad (maximum of approximately 200 x 200 ft. or 1.0 <br />acre) will be constructed to support the initial corehole drilling and subsequent borehole completion activities. The <br />10 -East Emergency Air Borehole installation will consist of the existing road access, the new borehole pad; <br />adjacent soil material stockpiles, and a cased and grouted borehole extending into the Wolf Creek Coal Seam. As <br />an emergency air borehole, following drilling and completion, the site will be accessed only in an emergency, and <br />�\ould not be accessed on a regular basis, so there is no need to establish and maintain a long-term access road. <br />Site-specific investigations completed for design and permitting of the Emergency Air Borehole include a cultural <br />resource survey and wildlife consultation. The cultural resource survey results are summarized by the survey report <br />provided in Exhibit 6L. and a wildlife consultation letter included in Exhibit 23C. The perimeter of all disturbed areas <br />be clearly marked, and construction drainage control measures (silt fences or wattles) will be installed prior to <br />disturbance. In order to reestablish effective vegetative cover during site reclamation, TC will recover and stockpile a <br />maximum of 1.0 foot of soil material from the pad disturbance areas. A maximum of approximately 1,900 cy of soil <br />will be recovered and stockpiled from the pad area. Natural vegetative materials incorporated into the salvaged soil <br />materials and seeding with the soil stockpile stabilization seed mixture will assist in stabilizing the stockpiled soil <br />material and preventing erosion or loss of the soil materials. <br />The pad, existing road access, and temporary access to the site are on a minor ridgelines, so upgradient drainage will <br />be limited. The limited amount of drainage from upgradient areas will be intercepted and routed around the borehole <br />pad by a small upgradient diversion ditch on the north and west sides of the pad, and the road will not cross any <br />natural drainages, so no culvert installations will be needed. Drainage from the borehole pad will be controlled under <br />a Small -Area Exemption. <br />Construction of the borehole pad will involve soil recovery, installation of the upgradient diversion, and cut/fill pad <br />construction. Given that the Borehole is intended for emergency use only, the pad will remain in place, but will be <br />stabilized Nvith vegetation by reseeding with the temporary revegetation seed mixture. For the initial core drilling, up <br />to a 12.0 -inch hole will be drilled to approximately 40 feet, and a temporary PVC sleeve will be installed as surface <br />casing. Core drilling will proceed using a 3.5 to 4.0 inch bit to the target depth of approximately 1,600 feet. If no <br />sTiniticant eater inflows are encountered during the core drilling phase, the temporary PVC sleeve will be replaced <br />v, ith a i 0-11Ich grouted steel surface casing to a depth of approximately 60 feet. If significant ground water inflows are <br />encountered, the PVC sleeve would be replaced with a larger steel surface casing (up to 14 -inch), allowing drilling <br />and casing of a larger diameter borehole to a depth below the water -bearing zone. <br />Borehole completion will involve drilling, installing, and grouting a steel surface casing (up to 14 -inch) in place to a <br />depth of approximately 60 feet (dependent on the ground conditions encountered). The borehole will then be <br />advanced by reaming the previously completed corehole to a diameter of either 8.75 inches (dry hole), or 11.0 to 13.0 <br />inches (significant water inflows). For the larger diameter borehole, large diameter casing would be carried to a depth <br />of approximately 800 feet to get below the water -bearing zone, then stepped down to a 4.5 -inch casing to depth. For <br />the smaller diameter borehole, 4.5 -inch casing would be carried from the surface to the full depth of approximately <br />1,600 feet to intercept the top of the Wolf Creek Coal Seam. Water, drilling fluids, and cuttings will be contained <br />within one or more excavated pits or portable steel tanks (porta-pits) on the borehole pad. The completed borehole <br />�N ill be cased and grouted to either 4.5 inches (dry hole), or 8.625 inches (significant water inflows), and fitted with a <br />threaded or locking cap for security. Basic design information for the 10 -East Emergency Air Borehole is provided in <br />Exhibit 53. <br />The 10 -East Emergency Air Borehole installation will remain in place until it is no longer needed to support ongoing <br />or anticipated future mining operations. Reclamation of this installation will involve plugging and sealing the <br />borehole, consistent vN ith State Engineer requirements; cutting -off the borehole casing below grade, regrading the pad <br />to its approximate original configuration, soil material replacement, and reseeding with TC's standard Rangeland Seed <br />Mix. Reseeding of the disturbed area will be completed during the first appropriate planting period following soil <br />material replacement. <br />MR16-295 2.05-45.28 03/04/16 <br />