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• Boring and casing of the thickener underflow boreholes <br />• Excavation of the pipeline trench, with temporary placement of excavated material adjacent to the trench <br />• Excavation of boring/jacking pits for underground pipeline crossings of Foidel Creek, RCR27, and the <br />railroad spur, or trenching of these areas <br />• Bedding and placement of the thickener underflow pipelines in the trench, and installation of intermediate <br />access manhole(s) <br />• Installation of moisture sensors, and connection of the pipelines to the thickener underflow systems from <br />the Washplant I and II Thickeners, along with associated pump controls and shut -off valves, and pressure <br />testing of the pipeline <br />• Controlled backfilling and compaction of excavated material in the trench <br />• Surface grading, soil material replacement, seeding with TCC's temporary stabilization seed mixture, and <br />placement of temporary BMPs to control runoff and erosion until vegetation was reestablished for all <br />project disturbance areas <br />The thickener underflow borehole surface casings extend approximately 4 feet above grade, and are capped and <br />locked. The borehole casing extends approximately 310 feet into sealed and abandoned mine workings in the <br />SWMD, and 510 feet into 6RT and 850 feet into 7RT, and discharge on the mine floor, where the fines settle -out <br />and the decant drains to the decant sumps, where submersible pumps recycle the water back to the surface. <br />The water is retained by coal barriers, as shown on the underground mine workings map. The barriers for the <br />refuse storage areas are minimum 250 -foot wide coal barriers between the EMD and the Northern Mining District, <br />and the SWMD and the WMD, respectively. These barriers currently retain accumulated water from mine inflows <br />and contain a submersible pumps at the low points for mine dewatering. These pumps are used to recycle water <br />back to the surface for washplant make -up water or underground for dust suppression, or the water will be <br />discharged directly to Foidel Creek. TC's existing discharge permit was modified to allow discharge directly to <br />Fish Creek. Water from the EMD and SWMD is pumped to the surface at the 10 -Right Borehole and Fish Creek <br />Borehole locations, respectively. <br />The water recycling/discharging system required minor changes to the existing water distribution system. Water <br />pumped from the mine exits the mine at Site 109. From this point, the water is piped to the Area 1 Pit where it is <br />retained to allow for settling of sediments and aeration. A pump station has been installed towards the south end of <br />the pit. Installation involved burying forty-foot beams under the road and extending them over the pit. A platform <br />was constructed on the beams extending over the pit. A submersible pump, along with hosing and piping, is <br />suspended from the platform into the pit. A winch installed on the platform assists in setting the pump at the <br />desired elevation. A second pump was added to provide make -up water for Washplant II. Control equipment for <br />this second pump was installed at the existing pump platform location <br />The water pumped from the Area 1 Pit can go in one of four directions, or a combination of them: 1) Pit to <br />Washplant I; 2) Pit to Washplant II; 3) Pit to mine water recycling line; and/or 4) Discharge to Foidel Creek. The <br />water pumped from the pit is piped to a de- sander, located at an old well site. From this point it is piped to one or <br />both of the washplants or piped over and tied into the existing mine water line. A line has been installed from the <br />de- sander back to the pit so that the back -flush water can be returned to the pit. The location of the lines is shown <br />on Map 24. The trenches were dug with a backhoe or trackhoe. During the excavation process suitable plant <br />growth media was removed and windrowed adjacent to the trench and then replaced on top of the subsoils returned <br />to the trench. <br />MR13 -270 2.05 -97.4 11/06/13 <br />