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• Bedding and placement of the Thickener Underflow Pipelines and secondary containment culvert in the <br /> trench, and installation of intermediate access manhole(s) <br /> • Installation of differential pressure gauges, and connection of the pipelines to the Thickener Underflow <br /> systems from the Washplant I and II Thickeners, along with associated pump controls and shut -off valves, <br /> and pressure 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 casing extends approximately 4 feet above grade, and is capped and <br /> locked. The borehole casing extends approximately 310 feet into sealed and abandoned mine workings in the <br /> SMD, and discharges on the mine floor, where the fines settle -out and the decant drains to the decant sump, where a <br /> submersible pump recycles 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 SMD and the Western Mining District, respectively. These barriers currently retain accumulated water <br /> from mine inflows and contain a submersible pumps at the low points for mine dewatering. These pumps will be <br /> used to recycle water back to the surface for washplant make -up water or underground for dust suppression, or the <br /> water will be discharged directly to Foidel Creek. TCC's existing discharge permit was modified to allow <br /> discharge directly to Fish Creek. Water from the EMD and SMD is pumped to the surface at the 10 -Right Borehole <br /> and Fish Creek 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 sub -soils returned <br /> to the trench. <br /> • <br /> TR09 -67 2.05 -97.7 11/10/09 <br />