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and construct or improve roads,placement of gravel as surfacing for the light-use road, excavation of temporary cuttings pits
<br /> on the drill-pads, drilling and casing of the boreholes, and installation of protective access manholes. On completion of
<br /> drilling and casing operations, the cuttings pits are allowed to dry-out, material excavated from the pits is replaced and
<br /> graded, and the pad surface is graveled to control erosion and sediment and provide an all-weather operating surface. The
<br /> completed thickener underflow borehole installations include light-use road access, one or more soil material stockpiles (pad
<br /> and road);the drill-pad(1 MN—25 x 180 feet, 6RT-70 x 70 feet, 7RT— 100 x 75 feet,2MN—75 x 75 feet,2SW—250 x 170
<br /> feet max, 1 SW 175 x 175 feet max, 12, 14, 15, 16, &17-Left—200 x 200 feet max, Sandstone Sub—75 x 75 feet); the 6-to
<br /> 12-inch cased boreholes, 16 to 18-inch cemented surface casings, and covered 8-foot diameter CMP culvert manholes with
<br /> lightning protection. The Sandstone Sub Borehole, because it will be completed on the existing substation pad, will not
<br /> require soil handling, an access road,pad construction, or surface casing or a manhole, and drainage will be contained on the
<br /> pad by a constructed berm.
<br /> With timing and weather constraints, portions of the pipeline may be temporarily installed on the surface, to be buried
<br /> when ground conditions are more favorable. Pipeline installation will involve removal and windrowing of soil materials
<br /> from the pipeline construction corridor(maximum-40-foot wide); trenching in most areas; placement of suitable bedding
<br /> materials; placement, connection, and pressure testing of the pipelines; backfilling and compaction of suitable fill
<br /> materials around and over the pipelines; backfilling and compaction of the trench; regrading; replacement of soil
<br /> materials; and revegetation of all disturbed areas. Where the pipelines pass under RCR27, the Twentymile Mine railroad
<br /> spur, Foidel Creek, and Fish Creek, the pipeline trench will be expanded to provide room for horizontal boring or jacking
<br /> equipment, and the pipelines will be trenched, bored, or jacked under these features. Because pipeline placement and
<br /> construction of portions of the 6RT, 7RT, 1MN, 2MN, 12, 14, 15, 16, & 17-Left and SWMD pads will necessarily involve
<br /> activities within the Foidel Creek or Fish Creek buffer zones, TC is requesting a temporary variance for pipeline
<br /> construction and a longer-term variance for the limited pad areas from the regulatory requirements for operations within a
<br /> buffer zone. The pipelines will be a double HDPE pipe system in critical areas (note that entire 6RT, 7RT, 2MN, 12 left,
<br /> and SWMD pipelines will be double-pipe systems), with a 6 to 8- inch carrier pipe inside a larger (maximum size - 12-
<br /> inch diameter) containment pipe, buried approximately 5-feet deep. The 1MN pipeline will extend approximately 1,800
<br /> feet, with the 6RT pipeline extending approximately 8,000 feet, and continuing another 1,600 feet to 7RT. The 6RT/7RT
<br /> pipeline is immediately adjacent to the 2MN Borehole, so only a short connecting pipe was necessary. The SWMD
<br /> pipeline will extend approximately 6,700 feet from the 1MN TUF pipeline to the 2SW SWMD Borehole and will fall
<br /> within the previous disturbance areas for the Haulroad C corridor and the 18-Left Mine Water Transfer Pipeline.
<br /> To accommodate for the need to increase the slurry volume from the washplant to the thickener boreholes a new pipeline
<br /> will be installed from the washplant to the SWMD boreholes. The additional pipeline will be placed in the same ditch as
<br /> the existing pipeline so there will be no new disturbance associated with the new pipeline. The pipeline will consist of
<br /> double wall HDPE pipe with a 12 inch outer pipe and 8 inch inner pipe. The existing risers will be tied into the new line
<br /> along with all the pumps and controls along the route.
<br /> A pump boost station was added at the 2SW borehole to provide sufficient pumping capacity to efficiently move the coal
<br /> fines slurry through the pipeline network to all of the designated locations. The pipeline will extend approximately 2,930
<br /> feet beyond the 2SW borehole to reach the 1 S Borehole location. An additional pipeline (12-Left pipeline) will tee off
<br /> of the pipeline running from the 2SW borehole to the 1 SW borehole on the east side of RCR27. The pipeline will parallel
<br /> RCR27 for an additional 5,800 feet, extending to the northwest, crossing under Fish Creek, and then a tee will be installed
<br /> to route the thickener either 1,940 feet to the 12-Left borehole or 7,245 feet through 14, 15, and 16-Left boreholes on to the
<br /> 17-Left borehole. The Sandstone Sub pipeline will extend approximately 1,200 feet from the 1MN Borehole location.
<br /> Electronic moisture sensors, along with pump controls, and shut-off valves provide for timely detection, shut-off, and
<br /> isolation of the pipelines in the event of pipeline leakage. Access/inspection manholes and pipe-tees for the moisture
<br /> detection system are located at key points along the pipeline routes.During construction,and for the minor surface structures
<br /> that will remain during mining, drainage and sediment control will be provided by Alternative Sediment Controls (ASC's)
<br /> consisting of combined Best Management Practice(BMP) measures. As appropriate, ASC designs are included in the design
<br /> exhibits for each installation. BMP's for the construction activities include (BMP's for any stream buffer zone areas include
<br /> the general BMP's identified,as well as specific BMP's* as noted):
<br /> • Minimizing the area of surface disturbance
<br /> MR18-311 2.05-84.7 09/21/18
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