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and construct or improve roads, placement of gravel as surfacing for the light-use road, excavation of temporary
<br /> cuttings pits on the drill-pads, drilling and casing of the boreholes, and installation of protective access manholes. On
<br /> completion of drilling and casing operations, the cuttings pits are allowed to dry-out, material excavated from the pits
<br /> is replaced and graded, and the pad surface is graveled to control erosion and sediment and provide an all-weather
<br /> operating surface. The completed thickener underflow borehole installations include light-use road access, one or
<br /> more soil material stockpiles (pad and road); the drill-pad(1MN—25 x 180 feet, 6RT- 70 x 70 feet, 7RT— 100 x 75
<br /> feet, 2MN—75 x 75 feet, 2SW—250 x 170 feet max, 1 SW 175 x 175 feet max, 12, 14, 15, 16, &17-Left—200 x 200
<br /> feet max, Sandstone Sub— 75 x 75 feet); the 6- to 12-inch cased boreholes, 16 to 18-inch cemented surface casings,
<br /> and covered 8-foot diameter CMP culvert manholes with lightning protection. The Sandstone Sub Borehole, because
<br /> it will be completed on the existing substation pad, will not require soil handling, an access road, pad construction, or
<br /> surface casing or a manhole, and drainage will be contained on the pad by a constructed berm.
<br /> With timing and weather constraints, portions of the pipeline may be temporarily installed on the surface, to be
<br /> buried when ground conditions are more favorable. Pipeline installation will involve removal and windrowing of
<br /> soil materials from the pipeline construction corridor (maximum - 40-foot wide); trenching in most areas;
<br /> placement of suitable bedding materials; placement, connection, and pressure testing of the pipelines; backfilling
<br /> and compaction of suitable fill materials around and over the pipelines; backfilling and compaction of the trench;
<br /> regrading; replacement of soil materials; and revegetation of all disturbed areas. Where the pipelines pass under
<br /> RCR27, the Twentymile Mine railroad spur, Foidel Creek, and Fish Creek, the pipeline trench will be expanded to
<br /> provide room for horizontal boring or jacking equipment, and the pipelines will be trenched, bored, or jacked under
<br /> these features. Because pipeline placement and construction of portions of the 6RT, 7RT, 1MN, 2MN, 12, 14, 15,
<br /> 16, & 17-Left and SWMD pads will necessarily involve activities within the Foidel Creek or Fish Creek buffer
<br /> zones, TC is requesting a temporary variance for pipeline construction and a longer-term variance for the limited
<br /> pad areas from the regulatory requirements for operations within a buffer zone. The pipelines will be a double
<br /> HDPE pipe system in critical areas (note that entire 6RT, 7RT, 2MN, 12 left, and SWMD pipelines will be double-
<br /> pipe systems), with a 6 to 8- inch carrier pipe inside a larger(maximum size - 12-inch diameter) containment pipe,
<br /> buried approximately 5-feet deep. The 1MN pipeline will extend approximately 1,800 feet, with the 6RT pipeline
<br /> extending approximately 8,000 feet, and continuing another 1,600 feet to 7RT. The 6RT/7RT pipeline is
<br /> immediately adjacent to the 2MN Borehole, so only a short connecting pipe was necessary. The SWMD pipeline
<br /> will extend approximately 6,700 feet from the 1MN TUF pipeline to the 2SW SWMD Borehole and will fall within
<br /> 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
<br /> pipeline will be installed from the washplant to the SWMD boreholes. The additional pipeline will be placed in the
<br /> same ditch as the existing pipeline so there will be no new disturbance associated with the new pipeline. The
<br /> pipeline will consist of double wall HDPE pipe with a 12 inch outer pipe and 8 inch inner pipe. The existing risers
<br /> will be tied into the new line 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
<br /> the coal fines slurry through the pipeline network to all of the designated locations. The pipeline will extend
<br /> approximately 2,930 feet beyond the 2SW borehole to reach the 1SW Borehole location. An additional pipeline
<br /> (12-Left pipeline) will tee off of the pipeline running from the 2SW borehole to the 1 SW borehole on the east side
<br /> of RCR27. The pipeline will parallel RCR27 for an additional 5,800 feet, extending to the northwest, crossing
<br /> under Fish Creek, and then a tee will be installed to route the thickener either 1,940 feet to the 12-Left borehole or
<br /> 7,245 feet through 14, 15, and 16-Left boreholes on to the 17-Left borehole. The Sandstone Sub pipeline will extend
<br /> approximately 1,200 feet from the 1MN Borehole location. Electronic moisture sensors, along with pump controls,
<br /> and shut-off valves provide for timely detection, shut-off, and isolation of the pipelines in the event of pipeline leakage.
<br /> Access/inspection manholes and pipe-tees for the moisture detection system are located at key points along the
<br /> pipeline routes.During construction, and for the minor surface structures that will remain during mining, drainage and
<br /> sediment control will be provided by Alternative Sediment Controls(ASC's)consisting of combined Best Management
<br /> Practice (BMP) measures. As appropriate, ASC designs are included in the design exhibits for each installation.
<br /> BMP's for the construction activities include (BMP's for any stream buffer zone areas include the general BMP's
<br /> identified, as well as specific BMP's*as noted):
<br /> • Minimizing the area of surface disturbance
<br /> MR18-311 2.05-84.7 08/22/18
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