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Section - 2.05.3 <br />The portal bench and road design, including the upslope slope stabilization activities, <br />have been evaluated relative to short-and long-term stability as summarized by the D- <br />Seam Portal Area Slope Stability Report (Abel, 1998), the Slope Stability Analyses for Elk <br />Creek Mine Bench Fills and Soil Stockpile (Montgomery Watson, 2000), and a <br />supplemental letter addressing establishment of a rock catch bench (Abel, 11/8/00) <br />which are included in Exhibit 2.05-E2, Geotechnical Design and Stability Analyses. <br />Drainage from the slope stabilization area will be controlled through integration of short- <br />and long-term surface stabilization and drainage control measures. Surface stabilization <br />measures will include establishment and maintenance of an upper rock catch bench, <br />grading to establish natural slope breaks and undulations, leaving the surface in a <br />roughened condition, surface revegetation and mulching, and the use of anchored straw <br />booms or similar surface flow and erosion control measures. These stabilization <br />measures will be supplemented by installation of field located and engineered rock <br />downdrains and a toe ditch that will intercept and route runoff of Sedimentation Pond <br />D. <br />D. Mine Portals and Declines -The Elk Creek Mine reserve area will be accessed by declines <br />driven from portals located near the D Seam subcrop in Elk Creek Canyon. Portal <br />installation and initial decline construction will involve cut/fill excavation and installation <br />of two sets (manway and conveyor/temporary ventilation entries) of steel circular or <br />arch support sections on a grade to reach competent ground. Select backfill materials <br />will be placed and compacted around and over the portal structures to assure the stability <br />of these structures during operations. Development will continue, with soft-ground <br />excavation of the two 10 x 20 foot main decline entries to the north to intercept the D <br />Coal Seam. Portal entries will be driven on approximately 100-foot centers. A third <br />entry will be added approximately 250 feet north of the point where soft-ground <br />development is initiated. Material excavated from the declines is classified as none <br />development waste and will be utilized as fill material for the Elk Creek portal bench and <br />road if compatible with design compaction specifications. Any unsuitable or saturated <br />materials will be hauled to and placed in the West Valley Fill in a manner that facilitates <br />effective drainage and consolidation. <br />E. Ventilation Shafts and Fan Installation(s) -Where the main entries intercept the D Coal <br />Seam, the entries will be turned to the west and expanded to a full five-entry <br />configuration. Two ventilation shafts will be sunk from the surface to intercept the main <br />entries. Material excavated from the ventilation shafts will be utilized as fill material for <br />the Elk Creek portal bench and access road if compatible with design compaction <br />specifications. A ventilation fan(s) will be installed on one or both shaft(s) to increase <br />ventilation airflow and pressures. Atypical fan installation will consist of a ventilation <br />fan, steel fan housing and ductwork, drive motor, and fan controls mounted on a <br />concrete slab foundation. Power will be provided to the fan drive motor from the mine <br />electrical distribution system. <br />An additional fansite is located on the Blue Ribbon minesite along Hubbard Creek. This <br />fansite, referred to as the Hubbard Creek Fansite, consists of a fan, ducting, motor and <br />controls located on a concrete slab foundation and an electrical substation also located <br />on a concrete slab foundation. Development material from excavation of the facility pad <br />and driving of the shaft associated with the fan will be stockpiled to the west of the pad. <br />Topsoil recovered Erom the disturbance area will be stockpiled south of the fansite pad. <br />Existing surface water control measures from the Blue Ribbon Mine operation will be <br />used in conjunction with new facilities for water management. Water from the area of <br />disturbance will be routed to the existing sediment treatment pond at the site. This <br />sediment pond, denoted as Sediment Pond F, will be cleaned as part of site development. <br />TR-60 2.05-22a Revised September 2008 <br />