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proposed Bleeder Shaft pad area is less than natural settleable solids concentrations for runoff from undisturbed lands,
<br /> given similar conditions.
<br /> The upgradient diversion ditches will be triangular ditches designed to safely divert the peak flow from the 10-year,24-
<br /> hour storm with a minimum of 1-foot of freeboard and located as shown on Figure 1, Bleeder Shaft Pad SAE. The
<br /> shaft pad will be constructed such that it slopes toward the gravel filter. The check dam and grass filter efficiency was
<br /> modeled using the SEDCADTM4 check dam and grass filter utility. Exhibit 5 is submitted to demonstrate that
<br /> application of diversion ditches, drainage collection ditches, wattles, Curlex blankets, and the sump, rock check dam,
<br /> and grass filter can effectively control and treat runoff from this area.
<br /> 6MN Mine Water Storage Reservoir and Ancillary Facilities—The 6MN Reservoir installation will include a water-
<br /> supply inlet pipeline from the 10-Right Mine Dewatering Transfer Pipeline(includes a pipeline crossing of Fish Creek);
<br /> the reservoir itself (basin, embankment, emergency spillway, and outlet channel); a clean-water diversion ditch;
<br /> discharge pump station,pad,and associated light-use road;discharge pipeline to the 6MN Million-Gallon Tank;and an
<br /> associated topsoil stockpile. The reservoir,emergency spillway,discharge channel,and diversion channel are designed
<br /> structures,with relevant design information provided in Exhibit BCC. Drainage and sediment control for the remaining
<br /> components will be addressed through Alternative Sediment Controls (ASC's) and/or Best Management Practices
<br /> (BMP's).
<br /> As a limited and temporary disturbance, drainage and sediment control for the pipeline construction activities will be
<br /> addressed through the application of a package of site-specific BMP's. Prior to initiation of pipeline construction,and
<br /> as pipeline construction advances, sediment control materials (straw wattles or silt fence) will be placed downslope
<br /> of the disturbance at any location where the pipeline corridor is within 50 feet of a drainage or stream buffer zone
<br /> and available soil material will be removed and windrowed adjacent to the disturbance area.. Where the pipeline
<br /> disturbance is not near drainages or stream buffer zones, existing natural vegetation will provide an effective
<br /> vegetative filter to address any anticipated sediment control requirements. Progressive backfilling, soil
<br /> replacement, and revegetation of the pipeline disturbance immediately following pipeline installation will serve to
<br /> minimize any short- or long-term impacts. .Where the pipeline crosses under Fish Creek, BMP's at the crossing
<br /> location will include placement of stream buffer zone markers at any point where the pipeline corridor is within 50
<br /> feet of the stream buffer zone prior to any activity; completion of the work during low-flows; placement of silt
<br /> fence or anchored straw bales at least 50 feet downstream to catch any sediment released prior to initiation of work;
<br /> placement of sediment control materials (straw wattles or silt fence) around the entire side and near stream
<br /> perimeters of the jacking pit disturbance areas; restrictions on storage or transfers of petroleum products within the
<br /> buffer zone; and reclamation of the affected areas immediately following completion of pipeline installation.
<br /> Construction and sediment control details are shown by the design drawings in Exhibit 490.
<br /> Reservoir slopes and surfaces (out-slope and top of embankment), pad and road out-slopes, and topsoil pile will be
<br /> stabilized and protected from erosion by seeding with the standard temporary stabilization seed mixture, on
<br /> completion of construction. The upstream embankment of the Reservoir, emergency spillway, diversion channel,
<br /> and outlet channel will all be riprapped, per the design specifications. Drainage and erosion control will be
<br /> addressed on the pump pad surface and light-use road through placement of gravel surfacing materials.
<br /> Supplemental drainage and sediment protection for the topsoil pile will be provided through placement of sediment
<br /> control materials (straw wattles or silt fence) around the perimeter of the stockpile until an effective vegetative
<br /> cover becomes established.
<br /> Thickener Underflow Boreholes and Prelines(TR07-60,TR09-69,TR16-86,MR07-221,MR10-242,MR10-248,
<br /> MR13-270,MR13-273,MR17-303)—TC has or will complete new thickener underflow boreholes in both the SWMD
<br /> and the EMD,and install new thickener underflow pipelines to convey fine coal refuse,as a slurry,from the washplants
<br /> to these locations. With the exception of the surface casings and any protective manhole structures for the underflow
<br /> boreholes, surface disturbance for the Thickener Underflow Pipelines and Boreholes will be temporary and surface
<br /> activities will be limited to pipeline/borehole installation activities.
<br /> The 1 MN Thickener Underflow Borehole is located to the west of the previous CYCC Office Building (Brown
<br /> Palace) location, along the existing light-use road,and extends approximately 310 feet into the sealed and abandoned
<br /> mine workings in the SWMD. The 6RT Thickener Underflow Borehole installation is located southeast of the
<br /> intersection of Routt County Roads 27 (RCR27) and 33 (RCR33), on the north side of Foidel Creek and the
<br /> MR 17-303 2.05-84.5 01/27/17
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