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FEB,2Q.2002 5~43PM TWENTYMILE CORL ENVIRONMENTAL N0.475 from these areas will either be windrowed adjacent to the road corridor or placed in stockpile adjacent to the shaft pad for future reclamation use. The topsoil salvage volumes are indicated on Table 49A. Seeding with the topsoil stockpile stabilization seed mixture will stabilize the windrowed and stockpiled topsoil. Following topsoil removal, required drainage and sediment control structures will be constructed ar installed, These structures include designed culverts for the road crossing of Fish Creek (nee Exhibit SR, Fish Creek Culvert Design, NVV Mains Ventilation Shai3) and road crossings of smaller ephemeral drainage channels; discharge control strucnue (rock check dam) of the downgradient limit of the shaft pad, and a temporary diversion ditch around the upgradient perimeter of the shaft pad, The drainage from the shaft pad is addressed under a Small Area Exemption (SAE) section of the permit, as it is a relatively small (approximately 1.8 acres), gravel-surfaced and or reclaimed area. The access road follows relatively level terrain and will be gravel surfaced, so access road drainage control requiremems are minimal. All drainage calculations and documentation is provided in Exhibit 8S, the SAE demonstration is provided later in this section, and the drainage structures are shown on Map 24. The SAE demonstration includes ditch sizing for the upland diversion ditch and road ditch. Tha access road into the shaft pad crosses Fish Creek, and TCC will place "Suffer Zone" signs at the boundary of the stream crossing disturbance. Bxcept for the disturbance associated with the stream crossing no further activity is planned within the Buffer Zoae boundary. Construction of the ventilation shaft access road involves topsoil recovery and windrowing or stockpiling, installation of required drainage structures, scarification and re-compaction of surface materials, placement of geotextile in selected areas, and placement and compaction of approximately 8°' of pit-run gravel and 3" of road- basamaterial. The access rand surface wiU be approximately 22' wide and will be graded and crowned to promote effective drainage. Road construction requires minimal cut, and limited fills in the area of the Fish Creek drainage crossing, Fill slopes will be graded to a 3I3:1V and stabilized by seeding with the topsoil stockpile stabilization seed mixture, Preparation of the ventilation shaft pad involves topsoil recovery and stockpiling, instatlation of required drainage structures, grading and compaction to establish a lave] pad Working area, excavation of mud pits for drilling of the shaft pilot hole, temporary stockpiling of the excavated material, and placement of gravel surfacing material to control dust and sediment from the pad area Mud pits will be approximately 20' x 20' x 8' deep and are sized to contain all drilling fluids. In the event unanticipated ground water flow into the boring is encountered then the pits may ba enlarged or additional pits excavated to handle the flow. The ventilation shaft pilot hole will be drilled using a reverse circulation drill rig to drill a 14" nominal diameter pilot hole from the surface to a depth of approximately 1450'. The shaft collar area wi116e excavated to a depth of approximately 20', a collar liner, consisting of steel ring beams and liner plate will be placed, and the annulus between the liner and the collar excavation cemented. A temporary head-frame will be erected on the shaft Dollar structure over the pilot hole to support and handle the shaft boring equipment. The shaft boring drive unit will be installed on the shaft collar structure in preparation for shaft boring operations. During drilling, all drilling fluids will be contained in the exaavated mud pits and drilling fluids are generally re-circulated. Shaft boring and casing of the approximate 20' diameter ventilation shaft are conducted as separate operations. Asurface-mounted drive unit is used to turn a rotary cutting head attached to a shaft extending from the surface through the pilot hole, and a hoist on the temporary headframe is used to maintain continuous upward pressure an the nutter head, As boring progresses, the cuttings are dropped down the shaft bore and are recovered and then transported as follows: they may be placed in mined-out areas underground, they may be slurried to the BMD sump, or they may be stored on the gouwi in the previously approved overburden stockpile, south of the old pit. Slurrying would require installation of en underground line. The slurry would be pumped behind the seals in 7, 9 or 10 Right. If the cuttings are not placed underground they will be transported to the surface via the existing conveyance system and then will be stored south of the old pit. The cuttings volum4 will be approximately 21,000 cy (16,862 cy swelled by 25%), The cuttings will discharge off of the existing rock belt where they will be loaded into trucks and hauled to the mviausly approved overburden storage area (sea Map 24 for location). This overburden storage area is in a 02.176 2.05-45.1 02/ZD/D2