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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 drilling
<br /> and casing operations,the cuttings pits are allowed to dry-out,material excavated from the pits is replaced and graded,and the
<br /> pad surface is graveled to control erosion and sediment and provide an all-weather operating surface. The completed thickener
<br /> underflow borehole installations include light-use road access, one or more soil material stockpiles (pad and road); the drill-
<br /> 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 feet max, 1 SW 175
<br /> x 175 feet max, 12, 14, 15, 16, &17-Left — 200 x 200 feet max, Sandstone Sub — 75 x 75 feet); the 6- to 12-inch cased
<br /> boreholes, 16 to 18-inch cemented surface casings, and covered 8-foot diameter CMP culvert manholes with lightning
<br /> protection. The Sandstone Sub Borehole, because it will be completed on the existing substation pad, will not require soil
<br /> handling, an access road, pad construction, or surface casing or a manhole, and drainage will be contained on the pad by a
<br /> constructed berm.
<br /> With timing and weather constraints,portions of the pipeline may be temporarily installed on the surface,to be buried when
<br /> ground conditions are more favorable. Pipeline installation will involve removal and windrowing of soil materials from the
<br /> pipeline construction corridor(maximum-40-foot wide);trenching in most areas;placement of suitable bedding materials;
<br /> placement, connection, and pressure testing of the pipelines; backfilling and compaction of suitable fill materials around
<br /> and over the pipelines; backfilling and compaction of the trench; regrading; replacement of soil materials; and revegetation
<br /> of all disturbed areas. Where the pipelines pass under RCR27, the Twentymile Mine railroad spur,Foidel Creek, and Fish
<br /> Creek, the pipeline trench will be expanded to provide room for horizontal boring or jacking equipment, and the pipelines
<br /> will be trenched, bored, or jacked under these features. Because pipeline placement and construction of portions of the
<br /> 6RT, 7RT, 1MN, 2MN, 12, 14, 15, 16, & 17-Left and SWMD pads will necessarily involve activities within the Foidel
<br /> Creek or Fish Creek buffer zones,TC is requesting a temporary variance for pipeline construction and a longer-term variance
<br /> for the limited pad areas from the regulatory requirements for operations within a buffer zone. The pipelines will be a
<br /> double 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, buried
<br /> approximately 5-feet deep. The 1MN pipeline will extend approximately 1,800 feet, with the 6RT pipeline extending
<br /> approximately 8,000 feet, and continuing another 1,600 feet to 7RT. The 6RT/7RT pipeline is immediately adjacent to the
<br /> 2MN Borehole, so only a short connecting pipe was necessary. The SWMD pipeline will extend approximately 6,700 feet
<br /> from the 1MN TUF pipeline to the 2SW SWMD Borehole and will fall within the previous disturbance areas for the
<br /> 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 from the West side of Pond D to the boreholes but will be routed around the South side of pond D
<br /> along Haul Road B to the new thickener tank site. The pipeline will consist of double wall HDPE pipe with a 12 inch outer
<br /> pipe and 8 inch inner pipe.A 3 inch water line will also be ran alongside the thickener line to the booster pump for washdown
<br /> water. The existing risers 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 the coal
<br /> fines slurry through the pipeline network to all of the designated locations.In 2019 a 10'X 18'pre-fabricated master control
<br /> building, an additional transformer, and an 18' X 32' addition to the pump building to house an additional pump system
<br /> will be added to the pump station to assist in the pumping operations of the larger additional pipeline network.
<br /> The pipeline will extend approximately 2,930 feet beyond the 2SW borehole to reach the 1 SW Borehole location. An
<br /> additional pipeline (12-Left pipeline) will tee off of the pipeline running from the 2SW borehole to the 1 S borehole on
<br /> the east side 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 7,245
<br /> feet through 14, 15,and 16-Left boreholes on to the 17-Left borehole.The Sandstone Sub pipeline will extend approximately
<br /> 1,200 feet from the 1MN Borehole location. Electronic moisture sensors, along with pump controls, and shut-off valves
<br /> provide for timely detection, shut-off, and isolation of the pipelines in the event of pipeline leakage. Access/inspection
<br /> manholes and pipe-tees for the moisture detection system are located at key points along the pipeline routes.During
<br /> construction,and for the minor surface structures that will remain during mining,drainage and sediment control will be provided
<br /> by Alternative Sediment Controls(ASC's)consisting of combined Best Management Practice(BMP)measures. As appropriate,
<br /> ASC designs are included in the design exhibits for each installation. BMP's for the construction activities include(BMP's for
<br /> any stream buffer zone areas include the general BMP's identified,as well as specific BMP's*as noted):
<br /> • Minimizing the area of surface disturbance
<br /> M R18-312 2.05-84.7 04/18/2019
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