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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 shaft
<br /> pad will be constructed such that it slopes toward the gravel filter. The check dam and grass filter efficiency was modeled
<br /> using the SEDCADTM4 check dam and grass filter utility. Exhibit 5 is submitted to demonstrate that application of
<br /> diversion ditches,drainage collection ditches,wattles, Curlex blankets, and the sump,rock check dam, and grass filter
<br /> can effectively control and treat runoff from this area.
<br /> 6MN Mine Water Storaze Reservoir and Ancillary Facilities (TR07-61, TR07-62, TR16-84, MR07-224,MR08-
<br /> 2�—The 6MN Reservoir installation will include a water-supply inlet pipeline from the 10-Right Mine Dewatering
<br /> Transfer Pipeline (includes a pipeline crossing of Fish Creek); the reservoir itself(basin, embankment, emergency
<br /> spillway, and outlet channel); a clean-water diversion ditch; discharge pump station,pad,and associated light-use road;
<br /> discharge pipeline to the 6MN Million-Gallon Tank; and an associated topsoil stockpile. The reservoir, emergency
<br /> spillway,discharge channel,and diversion channel are designed structures,with relevant design information provided in
<br /> Exhibit 8CC. Drainage and sediment control for the remaining components will be addressed through Alternative
<br /> Sediment Controls(ASC's)and/or Best Management Practices(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 as
<br /> pipeline construction advances, sediment control materials (straw wattles or silt fence) will be placed downslope of
<br /> the disturbance at any location where the pipeline corridor is within 50 feet of a drainage or stream buffer zone and
<br /> 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 replacement,
<br /> and revegetation of the pipeline disturbance immediately following pipeline installation will serve to minimize any
<br /> short- or long-term impacts. .Where the pipeline crosses under Fish Creek, BMP's at the crossing location will
<br /> include placement of stream buffer zone markers at any point where the pipeline corridor is within 50 feet of the
<br /> stream buffer zone prior to any activity;completion of the work during low-flows;placement of silt fence or anchored
<br /> straw bales at least 50 feet downstream to catch any sediment released prior to initiation of work; placement of
<br /> sediment control materials(straw wattles or silt fence)around the entire side and near stream perimeters of the jacking
<br /> pit disturbance areas; restrictions on storage or transfers of petroleum products within the buffer zone; and
<br /> reclamation of the affected areas immediately following completion of pipeline installation. Construction and
<br /> 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 addressed
<br /> on the pump pad surface and light-use road through placement of gravel surfacing materials. Supplemental drainage
<br /> and sediment protection for the topsoil pile will be provided through placement of sediment control materials(straw
<br /> wattles or silt fence)around the perimeter of the stockpile until an effective vegetative cover becomes established.
<br /> Thickener Underflow Boreholes and Pipelines(TR07-60,TR09-69,TR16-86,TR17-87,TR17-88,TR18-90,MR07-
<br /> 221,MR10-242,MR10-248,MR13-270,MR13-273,MR17-303)—TC has or will complete new thickener underflow
<br /> boreholes in the SWMD,WMD,and the EMD,and install new thickener underflow pipelines to convey fine coal refuse,
<br /> as a slurry,from the washplants to these locations. With the exception of the surface casings and any protective manhole
<br /> structures for the underflow boreholes,surface disturbance for the Thickener Underflow Pipelines and Boreholes will be
<br /> temporary and surface activities will be limited to pipeline/borehole installation activities.
<br /> The 1MN Thickener Underflow Borehole is located to the west of the previous CYCC Office Building(Brown Palace)
<br /> location, along the existing light-use road, and extends approximately 310 feet into the sealed and abandoned mine
<br /> workings in the SWMD. The 6RT Thickener Underflow Borehole installation is located southeast of the intersection
<br /> of Routt County Roads 27(RCR27)and 33 (RCR33),on the north side of Foidel Creek and the
<br /> TR18-90 2.05-84.5 12/18/18
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