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using a hydrostatic steel liner. The steel liner sections will be pre- fabricated off -site, hauled to the site and field
<br />welded in 30 -50 foot joints. The liner will be floated into place. This is accomplished by securing a steel bulkhead
<br />to the bottom joint and leaving the excavated hole full of water while the liner is being lowered into place. By
<br />. calculating the buoyancy of the liner, and adding water to the capped liner column, as needed, the liner is easily and
<br />safely lowered into position. Once the liner is in place, a nominal 9 -inch thick grout seal will be pumped between
<br />the strata and liner. The grouted steel liner will serve to isolate the Twentymile Sandstone from the Wadge
<br />Overburden. As previously noted, TCC plans to pressure grout the Twentymile Sandstone to minimize seepage to
<br />the shaft. This will help assure that, after final closure, groundwater from this unit will be confined and not seep
<br />down the inside of the shaft.
<br />Upon completion of shaft drilling and steel liner installation for both shafts, the cuttings pit will be dewatered.
<br />Excess water will be hauled to the Area 1 Pit, and the remainder will be allowed to evaporate. After dewatering the
<br />cuttings pit and allowing the cuttings to consolidate and dry -out, the collection pit and cutting materials will be
<br />covered with stockpiled materials from the shaft collar excavation, graded and revegetated with a temporary cover.
<br />A sign(s) will be posted designating the temporary mine development waste pit. The cuttings and shaft collar
<br />excavation materials will be utilized to re -fill the shafts during eventual reclamation of the shaft installation.
<br />As shown on Map 23, additional entries will be driven from the 18 -Left gate -road to the north to connect with the
<br />two ventilation shafts. The entries will be driven in the same manner as is used in TCC's development work, i.e.
<br />continuous miners and shuttle cars.
<br />Following completion of shaft boring and casing operations and removal of the drilling equipment from the site,
<br />emergency hoist equipment, consisting of an escape capsule, hoist derrick, hoist drive unit, control equipment and
<br />18 x 24 foot pre - fabricated metal hoist house, and a pre- fabricated propane -fired shaft heater and ducting will be
<br />erected/installed on the previously constructed intake shaft concrete pad. The shaft heater will be connected to a
<br />propane supply tank, mounted on prefabricated concrete saddles, and a buried electrical cable. A chain -link
<br />security fence with a locked gate will be constructed to enclose the intake shaft and emergency hoist installation.
<br />Similarly, a fan enclosure (fan shroud), silencer, and electrical control building will be erected on the previously
<br />constructed exhaust shaft concrete pad, and the fan, fan drive motor, and electrical control, monitoring, and
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<br />communication systems will be installed. It is presently anticipated that the 400 hp, 90,000 cubic -foot per minute
<br />Robinson Fan and associated equipment will be relocated to the 18 -Left Ventilation Shaft from the EMD
<br />Ventilation Shaft location. In order to comply with new Mine Atmosphere Control (MAC) regulations, the cased
<br />nitrogen injection borehole will be connected to one or more manifolded pipe systems underground which will
<br />connect to sealed gob areas. At the surface, an 8 -foot diameter culvert manhole may be installed around the cased
<br />borehole(s) as a well -head, with appropriate grounding and lightning protection to meet MSHA requirements. The
<br />fixed pipeline(s) will connect at the surface to a portable skid - mounted nitrogen generator, which will operate in
<br />conjunction with associated portable compressors and controls. Required power for this installation will be
<br />provided by dropline from the existing 18 -Left Substation.
<br />As part of the 18 -Left Shaft project, TCC will complete a 14.75 -inch diameter borehole to a depth of approximately
<br />1,360 feet. The borehole will be completed with a 13 -inch diameter steel casing, a 6.625 -inch and two, 5.0 -inch
<br />diameter pipes will be installed within the casing, and the annulus will be grouted between the borehole and casing.
<br />It is anticipated that the 6.625 -inch pipe will be used as a mine dewatering borehole, and the two 5.0 -inch pipes for
<br />power drops or communication lines. Water from the WMD will be collected in a series of sumps, transferred to a
<br />pump station at the bottom of the 18 -Left Shaft, and pumped to the surface by a 320 HP high- capacity submersible
<br />pump, at a maximum rate of approximately 700 gpm. A new pipeline running approximately 8,200 feet from the
<br />18 -Left Shaft site to the southeast, will connect to the existing Fish Creek Mine Water Transfer Pipeline just to the
<br />east of the Fish Creek Water Treatment Facility. The 18LT Pipeline will be a 12 -inch HDPE pipeline with
<br />thermally- welded joints, buried below the frostline at a depth of approximately 5 feet. The pipeline will be
<br />installed under Routt County Road 27 by boring or jacking the pipeline under the road, and a crossing of Fish Creek
<br />will be either trenched through the creek during the winter low -flow period, or bored under the creek. Permitting
<br />• for pipeline installation includes approvals from the U.S Army Corps of Engineers (Nationwide Permit 12),
<br />CDPHE — Water Quality Control Division (Construction Dewatering Permit), notification of the Colorado Division
<br />of Water Resources, and a County Utility Install Right -of -Way Permit, as appropriate.
<br />TR09 -70 2.05-45.18 01/26/10
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