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and construct or improve roads,placement of gravel as surfacing for the light-use road, excavation of temporary cuttings
<br /> pits on the drill-pads,drilling and casing of the boreholes, and installation of protective access manholes. On completion
<br /> of 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
<br /> (pad and road); the drill-pad(1MN—25 x 180 feet, 6RT-70 x 70 feet, 7RT— 100 x 75 feet, 2MN—75 x 75 feet, 2SW—
<br /> 250 x 170 feet max, 1 S 175 x 175 feet max, 12, 14, 15, 16, &17-Left—200 x 200 feet max, Sandstone Sub—75 x 75
<br /> feet);the 6-to 12-inch cased boreholes, 16 to 18-inch cemented surface casings,and covered 8-foot diameter CMP culvert
<br /> manholes with lightning protection. The Sandstone Sub Borehole,because it will be completed on the existing substation
<br /> pad, will not require soil handling, an access road,pad construction, or surface casing or a manhole, and drainage will be
<br /> 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 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
<br /> bedding materials; placement, connection, and pressure testing of the pipelines; backfilling and compaction of suitable
<br /> fill 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
<br /> involve 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
<br /> a buffer zone. The pipelines will be a double HDPE pipe system in critical areas (note that entire 6RT, 7RT, 2MN, 12
<br /> left,and SWMD pipelines will be double-pipe systems),with a 6 to 8-inch carrier pipe inside a larger(maximum size-
<br /> 12-inch diameter) containment pipe, buried approximately 5-feet deep. The 1MN pipeline will extend approximately
<br /> 1,800 feet, with the 6RT pipeline extending approximately 8,000 feet, and continuing another 1,600 feet to 7RT. The
<br /> 6RT/7RT pipeline is immediately adjacent to the 2MN Borehole, so only a short connecting pipe was necessary. The
<br /> SWMD pipeline will extend approximately 6,700 feet from the 1MN TUF pipeline to the 2SW SWMD Borehole and
<br /> will fall 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
<br /> coal fines slurry through the pipeline network to all of the designated locations.In 2019 a 10'X 18'pre-fabricated master
<br /> control building,an additional transformer,and an 18'X 32' addition to the pump building to house an additional pump
<br /> system 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 SW borehole
<br /> on the east side of RCR27. The pipeline will parallel RCR27 for an additional 5,800 feet, extending to the northwest,
<br /> crossing under Fish Creek,and then a tee will be installed to route the thickener either 1,940 feet to the 12-Left borehole
<br /> or 7,245 feet through 14, 15, andl6-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, and
<br /> 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 pipeline
<br /> routes.During construction, and for the minor surface structures that will remain during mining, drainage and sediment
<br /> control will be provided by Alternative Sediment Controls (ASC's) consisting of combined Best Management Practice
<br /> (BMP) measures. As appropriate, ASC designs are included in the design exhibits for each installation. BMP's for the
<br /> construction activities include (BMP's for any stream buffer zone areas include the general BMP's identified, as well as
<br /> specific BMP's*as noted):
<br /> • Minimizing the area of surface disturbance
<br /> MR18-312 2.05-84.7 03/11/19
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