2010-06-04_PERMIT FILE - C1982056A (9)

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• Drilling of shaft pilot hole and grouting operations (as necessary) • Construction of temporary power • Construction of shaft collar structure and temporary drilling equipment pad • Shaft boring and casing operations • Erection of escape hoist buildings and equipment and installation of fence(s) • Installation and connection of escape hoist control equipment and systems • Installation of shaft heater and associated ancillary equipment • Driving of additional entries at the back of the 18 Right longwall panel • Boring and casing of Mine Atmosphere Control boreholes, and installation of modular methane drainage and nitrogen injection systems • Final clean -up and dressing of roads and site pads Site - specific investigations required for design and permitting of the new ventilation shaft included a cultural resource survey of potential disturbance areas, soil and foundation characterization as the basis for shaft pad and access road design, and completion of a wetland/AVF survey for the shaft pad and access road. The cultural resource survey was conducted by Metcalf Archaeological Consultants, the engineering soils characterization by Northwest Colorado Consultants, and the soils /wetland/AVF survey by Habitat Management, as described in Section 2.04. The perimeter of all areas affected by surface facilities will be clearly marked before the beginning of surface disturbances. The proposed shaft pad surface area is approximately 280' square (1.8 acres), with a total pad disturbance area (includes cut and fill slopes) of 2.5 acres. The associated access road corridor is approximately 7,100' long, with a finished top width of 24 feet (road corridor 35 feet wide, 5.7 acres). See Exhibit 25T, 18 Right Ventilation Shaft Geotechnical Pavement Design, for details on the road, and Map 24 -CD1, a new road profile and cross - section. Approximately 4,400 feet of the access road crosses upland areas, with the remaining 2,700 feet crossing lowland areas where road construction will involve removal of any large vegetation and stripping and stockpiling of other vegetation, topsoil, and organic materials. Given an average topsoil depth of approximately 6 inches in the upland area and a total road disturbance area of approximately 5.7 acres, approximately 4,600 CY of topsoil will be salvaged from the road corridor, and 2,000 CY from the 2.5 acre pad area. Prior to initiating topsoil removal activities, stream/wetland buffer zones will be marked with identifying signs to prevent surface disturbance within buffer zone areas. The topsoil from the road corridor was initially windrowed downslope beyond the edge of the 35 -foot road disturbance area, and topsoil from the pad area was placed in a stockpile adjacent to the shaft pad and within the 100 -foot road corridor, for future reclamation use. As a result of concerns related to protection of windrowed topsoil from erosion and contamination, a decision was made to recover topsoil from the windrows and place it in stockpile. The topsoil salvage volumes are indicated on Table 49A. Natural vegetative materials (mulch) incorporated into the topsoil, and seeding with the topsoil stockpile stabilization seed mixture identified on page 2.05 -121 will stabilize the windrowed and stockpiled topsoil. Following topsoil removal, required drainage and sediment control structures will be constructed or installed. These structures include the upslope road drainage ditch, road crossings of smaller ephemeral drainage channels; discharge control structure (rock check dam) at the down - gradient limit of the shaft pad, and a temporary diversion ditch around the up- gradient perimeter of the shaft pad. The drainage from the shaft pad is addressed under a Small Area Exemption (SAE), as both the associated drainage area (4.3 acres) and the pad disturbance (2.5 acres, includes 0.2 acre ditch disturbance) are relatively small, the pad will be gravel- surfaced, and the remainder of the drainage area is undisturbed and vegetated. The access road follows variable topography, generally consisting of rolling terrain, and will be gravel- surfaced, so access road drainage control requirements are minimal. A typical road drainage ditch design is provided in Figure 2 of Exhibit 8T, prepared by Water & Earth Technologies, Inc, April 2004. Six (6) culverts are required to remove the flow from the runoff ditches to limit runoff velocities in the ditches to less than or equal to 3.75 feet per second (fps). This will assure that the ditches remain stable with no channel scour or degradation during peak flow events. Breaks in the topsoil windrow will allow runoff to drain. All drainage calculations and documentation are provided in Exhibit 8T, the SAE demonstration is provided later in TR09 -66 2.05-45.4 02/17/09