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A second 14.75-inch diameter Utility Borehole will be completed to a depth of approximately 1,390 feet. A 60-foot <br />deep, 16-inch diameter surface borehole and surface casing will first be completed to support subsequent drilling <br />operations. The Utility Borehole will be completed with a 13-inch diameter grouted steel casing, an 8.625-inch and <br />a 4.5-inch diameter pipes will be installed within the casing, and the annulus will be grouted between the borehole <br />and casing. It is anticipated that the 8.625-inch pipe will be used as a rock-dust drop, and the 4.5-inch pipe for <br />compressed-air. The additional 18LT Rock-Dust Tank Installation will consist of a new rock-dust tank, which will <br />be mounted on four poured concrete piers; a connection to the new borehole; required electrical and control <br />equipment, that will tie-in to the existing 18LT Substation; and a dust collection system. The MCC Building <br />installation includes a 40 x 40 foot concrete pad and steel building and an 8 x 48 foot exterior concrete pad. In <br />order to accommodate the three large air compressors necessary to meet mine compressed air requirements, the <br />exterior concrete pad will be extended to 24 x 56 feet. Fourteen, 12-inch diameter holes will be bored <br />approximately 20 feet to bedrock, and surface materials in the pad extension footprint will be over-excavated, <br />replaced, and re-compacted. Reinforced concrete piers and pad will be pored to support the compressors and a pre- <br />fabricated steel building will be constructed on the extended pad to enclose the compressor installation. <br />Following commissioning, the shaft pad site, access road, and pipeline corridor will be cleaned-up and surface areas <br />graded and stabilized by seeding with the temporary seed mixture. When these facilities are no longer needed to <br />support ongoing or future mining and related operations, reclamation will involve removal of surface structures and <br />facilities, demolition of concrete foundations and pads, disposal of concrete debris in the shafts, replacement of <br />cuttings from the temporary cuttings pits in the shafts, grading of disturbance areas to blend with the surrounding <br />terrain, soil material replacement, and reseeding with the appropriate permanent revegetation seed mixture <br />(Pastureland Mixture for Shaft site and road, and Rangeland Mixture for Pipeline corridor). Boreholes will be <br />plugged and sealed in accordance with applicable State Engineer requirements, and pipelines will be cut-off below <br />grade, capped, and buried in-place. <br />WMD Stabilization Boreholes (MR11-253) <br />In order to address immediate safety and operational concerns associated with localized ground stability issues, TC <br />drilled two stabilization boreholes in the 17-Left Gateroad to allow concrete to be pumped into gateroad and <br />crosscut areas, forming a series of supplemental support pillars. <br />Activities associated with this ground stabilization effort included; <br />• Establishment of temporary drainage and sediment control measures <br />• Soil material removal and placement in a temporary stockpile <br />• Construction of a short temporary access road <br />• Construction of a 200' x 300' drill pad <br />• Drilling and casing of 2 boreholes from the pad <br />• Set-up of a portable concrete batch plant on the existing 18-Left Shaft Pad, or direct delivery of pre-mixed <br />concrete to the borehole site <br />• Extension of a temporary concrete transfer line on the ground surface between the batchplant and the drill- <br />site <br />• Pumping of concrete down the drillholes into the underground workings <br />• Plugging and sealing of the drillholes <br />• Reclamation and restoration of all related temporary surface disturbance <br />The location and configuration of the proposed activities are shown on Figure 49U-F1, WMD Stabilization <br />Boreholes. <br />Temporary drainage control and sediment control measures for these activities include placement of a 36-inch x 80 <br />foot CMP culvert in the borrow ditch for County Road 27 to allow road runoff to pass under the temporary access <br />road (culvert is sized to match the existing downgradient culvert crossing under the road), construction of a temporary <br />diversion ditch and catch basins upgradient of the drill pad to intercept and route any natural runoff around the pad, <br />and placement of straw wattles downgradient of the pad to intercept and control any runoff that escapes the pad. <br />Temporary drainage and sediment control measures will be in-place before any other activities proceed. <br />MR11-253 2.05-45.20 04/18/11