2011-09-28_PERMIT FILE - C1982056A (10)

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involve the following sequential activities, as briefly described in the following sections and shown on the design drawings provided in Exhibit 49Y: • • Completion of environmental and engineering investigations • Placement of disturbed area markers • Temporary drainage and sediment control measures • Recovery and stockpiling of available soil materials • Installation of drainage and sediment controls • Construction of a light -use road and site preparation for shaft pad • Construction of the shaft pad and lined cuttings pit • Installation of electrical distribution line and equipment • Excavation and construction of shaft collar structure • Blind - drilling and casing of the shaft • Construction of security fence around the shaft • Extension of entries from the 15 -Left gate -roads to connect to the shaft bottom • Installation of rock -dust drop pipe, rock -dust tank, and controls • Final clean -up and dressing of road and site pad Site - specific investigations required for design and permitting of the new ventilation shaft and pipeline include a cultural resource survey of potential disturbance areas, identification and marking of wetland limits, and wildlife consultation. The cultural resource survey was conducted by Metcalf Archaeological Consultants, with results summarized by the survey report included in Exhibit 6T. The wildlife consultation is documented by a consultation letter from the CDOW, provided in Exhibit 23C. The perimeter of all areas affected by surface facilities construction will be clearly marked before initiating any surface disturbance. The proposed shaft pad, cuttings pit, and soil stockpile area will have maximum dimensions of approximately 200 x 350 feet (1.6 acres) with cut and fill slopes. The light -use road, will add approximately 0.7 acres of disturbance, for a total disturbed area of approximately 2.3 acres. The light -use road disturbance corridor will be approximately 750 feet long and 40 feet • wide. Actual constructed road width (finished top width) is expected to be approximately 24 feet. Refer to Exhibit 49Y, 15LT Ventilation Shaft Installation — Design Drawings, for details on the road, and the road profile and cross - section. The proposed light -use road crosses upland areas where road construction will involve removal of any large vegetation and stripping and stockpiling of other vegetation, soil, and organic materials. In order to reestablish effective vegetative cover, TCC will recover and stockpile a maximum of 18 inches of soil material from shaft and road disturbance areas. With a total road disturbance area of approximately 0.7 acres, approximately 1,700 CY of soil material will be salvaged from the road corridor, and approximately 3,900 CY from the 1.6 acre shaft pad and associated disturbance areas. Prior to initiation of soil salvage operations, temporary sediment control measures (silt fence, wattles, and/or other, as appropriate) will be installed. Soil salvage volumes are indicated on Table 49A. Soil material from the road corridor and other disturbance areas will be stockpiled in a central soil stockpile areas as shown on the design drawings in Exhibit 49Y. Natural vegetative materials (mulch) incorporated into the soil, and seeding with the topsoil stockpile stabilization seed mixture identified on page 2.05- 121, will stabilize the stockpiled soil materials. Following soil removal, required drainage and sediment control structures will be constructed or installed. In order to minimize potential environmental and aesthetic impacts, surface drainage will be handled by an upslope drainage diversion ditch; a culvert crossing where this ditch intersects an existing natural drainage and crosses under the light -use road; and a interceptor ditch and rock -lined sump (Alternative Sediment Controls (ASC's)) on the downslope side of the pad. All drainage calculations and documentation are provided in Exhibit 49Y. Once the pad is constructed, surface runoff from the pad will be limited by placement of gravel surfacing material, and any limited surface drainage from the pad will flow to the cuttings pit. As a limited disturbance area, the pad, ditches, and ASC's will function under a Small Area Exemption to assure effective runoff and sediment control. Road drainage will be minimized by placement of gravel surfacing. Other disturbed areas (including topsoil stockpiles •and pad outslopes) will be stabilized with temporary vegetation, and any structures will be painted in neutral earth - tone colors to blend with the natural surroundings. TR11 -78 2.05-45.23 09/15/11