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PERMFILE113218
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PERMFILE113218
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Last modified
8/24/2016 10:09:24 PM
Creation date
11/24/2007 10:20:38 PM
Metadata
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Template:
DRMS Permit Index
Permit No
C1982056A
IBM Index Class Name
Permit File
Doc Date
5/21/2004
Section_Exhibit Name
2.05 Operation & Reclamation Part 2
Media Type
D
Archive
Yes
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to pump the thickener underflow into the abandoned mine works as opposed to mixing it with the course <br />refuse for placement in the refuse pile. The thickener underflow is typically a 25 percent solids (17.8 tons <br />• per hour), 214 gallons per minute flow mixture of ash and coal fines (28 mesh x 0). The mixture would be <br />piped to the abandoned works located in the EMD, where the fines would settle out and the water would be <br />recycled back to the wash plant via the mine sump for settling. Map 24 shows where the water will be <br />pumped back outside and recycled to the plant. <br />The quality of the thickener underflow that will be piped to the underground workings is typically 25 <br />percent ash and 75 percent coal fines material (28 mesh x 0). Also, Exhibit 9C, Underflow Chemical <br />Chazacterization, provides data on selected chemical constituents found in the underflow. The underflow is <br />moved in a slurry flowing approximately 214 gallons per minute. The water quality of the slurry is the <br />typical spoils water generated at the adjacent Colorado Yampa Coal Company. It is TCC's intent that the <br />water used to slurry the mixture underground will be recycled to the plant as make-up water. <br />Map 23 shows the area that will be filled with the refuse material over the next 20-year period. The <br />percent of the ENID abandoned workings that will contain these refuse fines, after the typical annual <br />production fora 20-year period, will be 1.63 percent. This is based on 25,000 tons of refuse fines <br />generated per year and 600 million cubic feet of storage in the East Mine District (only assumes a 30 foot <br />height in the gob area and permeability of 25 percent). <br />The source of hydraulic transport medium will be water from the thickener undertlow. The water/solids <br />mixture will be piped from the wash plant through a 4" HDPE pipeline underground for 1,800 feet to the <br />otd 4" mine water borehole, see Map 24 for location of pipelines. The borehole pipe will then be <br />connected to a 4" aluminum pipe on the mine floor for the remaining 5,000 feet to the mine gob seal. The <br />pipe will be connected to the existing drainpipe at the seal where it will flow onto the mine floor behind <br />the seals (gob side) and to the bottom of the gob area, Map 23 shows the area which will receive the <br />• underflow material. <br />The water/ solids mixture will be pumped behind the seals where the fines will settle out and the water will <br />travel to the submersible pump for dewatering back to the surface. The water is retained by the coal <br />barrier as shown on the underground mine workings map. <br />The retaining wall for this refuse storage area is a minimum 250-foot wide coal barrier between the EMD <br />and the Northern Mining District. This barrier currently holds mine inflow water and contains a <br />submersible pump at the low point for mine dewatering. This pump will be used to recycle water back to <br />the surface for wash plant make-up water, recycled underground for dust suppression, or discharged <br />directly into Foidel Creek. TCC understands that before this water can be discharged directly into Foidel <br />Creek its existing discharge permit will have to be amended to allow for this activity. <br />The water recycling/discharging system will require minor changes to the present water distribution <br />system. Water pumped from the mine exits the mine at site 109. From this point the water will be piped <br />over to the old pit where it will have time to settle and aerate. A pump station will be installed towards the <br />south end of the old pit. This will involve burying forty-foot beams under the road and extending them <br />over the pit. The beams may be placed in concrete if additional weight is required to act as a counter- <br />balance. Aplatform will be constructed on the beams extending over the pit. A submersible pump, along <br />with hosing and piping, will be suspended from the platform into the pit. A winch will be installed on the <br />platform to assist in setting the pump at the prescribed elevation. <br />The water pumped from the pit can go in one of three directions, or a combination of them. The directions <br />• are as follows: 1) pit to Prep Plant, 2) pit to mine water recycling line, and/or 3) discharge to Foidel Creek. <br />The water pumped from the pit will piped over to a de-sander, which will be located at an old well site, <br />from this point it will be piped to the Prep Plant or piped over and tied into the existing mine water line. A <br />line will be installed from the de-sander back to the pit so that the back flush water can be returned to the <br />pit. The location of the lines is shown on Map 24, which also indicates where the trenches will be <br />PR 03-06 2.05-97.2 05/07/03 <br />
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