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The perimeter of all areas affected by surface facilities will be clearly marked before the beginning of surface
<br />disturbances. The proposed shaft pad surface area is approximately 280' square (1.8 acres), with a total pad
<br />disturbance area (includes cut and fill slopes) of 2.5 acres. The associated access road corridor is approximately
<br />7,100' long, with a finished top width of 24 feet (road corridor 35 feet wide, 5.7 acres). See Exhibit 25T, 18 Right
<br />Ventilation Shaft Geotechnical Pavement Design, for details on the road, and Map 24-CD1, a new road profile and
<br />cross-section. Approximately 4,400 feet of the access road crosses upland areas, with the remaining 2,700 feet
<br />crossing lowland areas where road construction will involve removal of any large vegetation and stripping and
<br />stockpiling of other vegetation, topsoil, and organic materials.
<br />Given an average topsoil depth of approximately 6 inches in the upland area and a total road disturbance area of
<br />approximately 5.7 acres, approximately 4,600 CY of topsoil will be salvaged from the road corridor, and 2,000 CY
<br />from the 2.5 acre pad area. Prior to initiating topsoil removal activities, stream/wetland buffer zones will be
<br />marked with identifying signs to prevent surface disturbance within buffer zone areas. The topsoil from the road
<br />corridor was initially windrowed downslope beyond the edge of the 35 -foot road disturbance area, and topsoil from
<br />the pad area was placed in a stockpile adjacent to the shaft pad and within the 100 -foot road corridor, for future
<br />reclamation use. As a result of concerns related to protection of windrowed topsoil from erosion and
<br />contamination, a decision was made to recover topsoil from the windrows and place it in stockpile. The topsoil
<br />salvage volumes are indicated on Table 49A. Natural vegetative materials (mulch) incorporated into the topsoil,
<br />and seeding with the topsoil stockpile stabilization seed mixture identified on page 2.05-121 will stabilize the
<br />windrowed and stockpiled topsoil.
<br />Following topsoil removal, required drainage and sediment control structures will be constructed or installed.
<br />These structures include the upslope road drainage ditch, road crossings of smaller ephemeral drainage channels;
<br />discharge control structure (rock check dam) at the down -gradient limit of the shaft pad, and a temporary diversion
<br />ditch around the up -gradient perimeter of the shaft pad. The drainage from the shaft pad is addressed under a Small
<br />Area Exemption (SAE), as both the associated drainage area (4.3 acres) and the pad disturbance (2.5 acres, includes
<br />0.2 acre ditch disturbance) are relatively small, the pad will be gravel -surfaced, and the remainder of the drainage
<br />area is undisturbed and vegetated. The access road follows variable topography, generally consisting of rolling
<br />terrain, and will be gravel -surfaced, so access road drainage control requirements are minimal. A typical road
<br />drainage ditch design is provided in Figure 2 of Exhibit 8T, prepared by Water & Earth Technologies, Inc, April
<br />2004. Six (6) culverts are required to remove the flow from the runoff ditches to limit runoff velocities in the
<br />ditches to less than or equal to 3.75 feet per second (fps). This will assure that the ditches remain stable with no
<br />channel scour or degradation during peak flow events. Breaks in the topsoil windrow will allow runoff to drain.
<br />All drainage calculations and documentation are provided in Exhibit 8T, the SAE demonstration is provided later in
<br />this section, and the drainage structures are shown on Map 24. The SAE demonstration includes ditch sizing for the
<br />upland diversion ditch and road ditch.
<br />Construction of the ventilation shaft access road will involve topsoil recovery and windrowing, installation of
<br />required drainage structures, scarification and re -compaction of surface materials, and placement and compaction of
<br />approximately 8 inches of pit -run gravel and 3 inches of suitable road -base material. The access road surface will
<br />be approximately 24 feet wide and will be graded and crowned to promote effective drainage. Road construction
<br />requires minimal cut and limited fill, so the actual road disturbance area will average approximately 35 feet wide.
<br />Cut slopes will be established at a maximum of 1.5H:1 V and fill slopes will be graded to 2H:1 V or less, with all
<br />disturbed slopes to be stabilized by seeding with the topsoil stockpile stabilization seed mixture. For permitting
<br />purposes, a road disturbance corridor 100 feet wide has been defined as encompassing all project -related activities,
<br />including road construction and topsoil stockpiling/windrowing.
<br />Preparation of the ventilation shaft pad will involve topsoil recovery and stockpiling, installation of required
<br />drainage structures, grading and compaction to establish a level pad working area, excavation of a collection pit for
<br />blind drilling of the shaft pilot hole and shaft, haulage or stockpiling of the excavated borrow material, and
<br />placement of gravel surfacing material to control dust and sediment from the pad area. Excavated borrow material
<br />from the collection pit will be hauled to the nearby Fish Creek Loadout for use in final reclamation. The collection
<br />pit will be approximately 100 x 200 x 10 feet and is sized to contain all drilling fluids and cuttings. In the event
<br />unanticipated ground water flows are encountered, they would occur during drilling of the pilot hole when the
<br />collection pit would have significant excess capacity. The combination of excess capacity and flow controls should
<br />MRI 1-259 2.05-45.5 11/17/11
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