GENERAL34800 - Laserfiche WebLink

Home Browse Search

• Temporary drainage and sediment control measures • Recovery and stockpiling of available topsoil • Installation of drainage and sediment control structures • Construction of an access road and site preparation for shaft pad • Drilling of shaft pilot hole • Construction of temporary power source (e.g. diesel generator) • 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 • Driving of additional entries at the back of the 18 Right longwall panel • One borehole for communication/utility purposes • Final clean-up and dressing of roads and site pad Site-specific investigations required for design and permitting of the new ventilation shaft have been completed, and include: a cultural resource survey of potential disturbance areas, soil and foundation characterization as the basis for shaft pad and access road design, completion of a wetland/AVF survey for the shaft and access road. The cultural resource survey was conducted by Metcalf Archaeological Consultants (Exhibit 6N), the engineering soils characterization by Habitat Management (Exhibit 16C); the wetland/AVF survey by Habitat Management (Exhibit 16D), the geotechnical and pavement design for the access road by Northwest Colorado Consultants (Exhibit 25T), and the road drainage and Small Area Exemption (SAE) demonstration by Water & Earth Technologies {Exhibit 8T). The proposed shaft pad area is approximately 280' square (1.8 acres) and the associated access road corridor is approximately 7,100' long with a finished top width of 24 feet. See Exhibit 25T, 18 Right Ventilation Shaft Access Road Design, for details on the road. C 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 placement of geotextile and road fill over in-place soils. Given an average topsoil depth of approximately 6" in the upland area and a total disturbance area of approximately 4.9 acres, approximately 3,950 CY of topsoil will be salvaged from the road corridor, and 1,452 CY from the pad. The topsoil from these .areas will either be windrowed adjacent fo the road corridor or placed in stockpile adjacent to the shaft pad for future reclamation use. 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 or installed. These structures include road crossings of the smaller ephemeral drainage channels; discharge control structure (rock check dam) along 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 an SAE section of the permit, as it is a relatively small (approximately 4.3 acres) gravel- surfaced/reclaimed area. The access road follows variable topography and generally consists of rolling terrain, which will be gravel-surfaced. Thus, access road drainage control requirements are minimal. Atypical road drainage ditch design is provided in Figure 2 of Exhibit 8T. 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 ensure that the ditches remain stable with no channel scour or ,- degradation during peak flow events. All drainage calculations and documentation are l_ provided in Exhibit 8T. Drainage structures are shown on Map 24. The SAE demonstration includes ditch sizing for the upland diversion ditch and road ditch. Construction of the ventilation shaft access road involves topsoil recovery and windrowing or stockpiling, installation of required drainage structures, scarification and