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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 (1 MN — 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 />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 1SW 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 />• Placement of stream buffer zones markers prior to disturbance in or immediately adjacent to buffer zone areas*
<br />• Scheduling of construction activities during the dry summer or early winter periods
<br />• Placement of staked straw wattles, silt fencing, or plastic silt barrio materials downgradient of all surface
<br />disturbance areas to intercept any surface runoff and trap associated suspended solids
<br />• Installation of the Foidel Creek, Fish Creek, Fish Creek Tributary, RCR27, and railroad spur pipeline crossings
<br />as either trenched or bored/jacked pipeline crossings under Foidel Creek, Fish Creek, Fish Creek Tributary,
<br />TR18-90 2.05-84.7 04/05/18
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