2009-03-09_PERMIT FILE - C1982056A (2)

Home Browse Search

efficiency underflow system mixes the flocculant with the fine refuse stream, causing the refuse particles to agglomerate and settle from suspension. The decant water discharges through a filter and is recycled to the Washplant. The fine refuse slurry discharges through an 1,800-foot, 6-inch diameter discharge line connecting to an 8-inch drop-borehole and underground piping system, which carries the slurry to an area of sealed underground mine workings. Underground, water decants from the fine refuse slurry and flows downgradient to a sump where a pumping system is used to recover and recycle the water. When the new Washplant and Thickener were installed, a new Thickener Overflow Sump was constructed to contain minor amounts of washdown water and to serve as a temporary catch basin for the contents of the Thickener, if required for maintenance or under upset conditions. The Thickener Overflow Sump is located between the Refuse Conveyor and Sedimentation Pond D. The Thickener Sump is partially incised, incorporates a compacted clay liner to minimize seepage, and is sized to fully contain the contents of the Washplant II Thickener (150,000 gallons) plus minor amounts of washdown water and incident precipitation for the design event. Impoundment design, operation, and maintenance information for the Thickener is provided in Exhibit 8X. Given that the potential for both the Washplant I and Washplant II Thickeners to experience an upset or require maintenance at the same time is negligible, with completion of the Washplant II Thickener Overflow Sump, the Washplant I Thickener Overflow Sump was decommissioned, filled-in and replaced by a discharge pipe from the Washplant I Thickener to the new Washplant II Thickener Overflow Sump. As an incised and closed basin (ie: no outlet) the only potential inputs to the Sump are thickener overflow, washdown water, or minor incident precipitation, which are subsequently pumped back into the system by a portable floating pump installation. The fl- inch thickener overflow line has been extended to the new Thickener Overflow Sump (4,800 feet), allowing overflow from either thickener to be controlled by valves and routed to the Sump. Water level in the Sump is monitored and managed as part of the ongoing Washplant operations. Given the power and system control requirements for the Washplant, an associated Motor Control Center (MCC)/Office Building was constructed immediately adjacent to the Washplant. The MCC/Office Building houses electrical, control, and monitoring equipment for the Washplant and includes office space for Mine Surface • Facilities Staff. The building consists of three connected modular steel containers (2 - 8 x 40 x 10 feet high, and 1- 8 x 20 x 10 feet high), located on the north side of the Overland Conveyor and Washplant II. The building sets on a reinforced concrete slab floor (20 x 60 x 0.75 feet thick). In order to consolidate the primary coal-handling operations in one area, the coal sampling system was removed from the BOB area and replaced by a new Coal. Sampling Station, located on the Overland Conveyor, to the west of Washplant II and Sedimentation Pond D. The coal sampling system consists of an automated sweep sampler, which cuts samples from the coal stream on the Overland Conveyor at regular intervals, a small sample crusher, a sample splitter to reduce sample volume, and associated chute-work and control and dust collection systems. The coal sampling system is housed in a steel frame building with steel siding and roof (20 x 20 x 25 feet high), located on the south side of the Overland Conveyor. The building sets on a reinforced concrete slab floor (22 x 22 x 0.75 feet thick). A new 69 KV distribution line was extended approximately 300 feet from the existing 69KV line to a new substation location adjacent to the Overland Conveyer. Powerline construction involved the limited disturbance required to place 4 powerpoles, with pole placement avoiding the Foidel Creek buffer zone. Installation of the new dedicated Washplant Substation required construction of a 40 x 60 foot concrete pad, enclosed by an 8-foot high chain-link fence and installation of steel supports, transformers, and associated control and electrical switch-gear. Buried connections to the Area 1 Pit and existing freshwater supply line were established to supply make-up and washdown water for the Washplant II operations. Communications lines were also extended to connect the Washplant facilities with the other existing operations. Crushing and Sampling Facilities (Modified and Superceded by TR07-59 for Washplant I)1 As previously described, the 72-inch Overland Conveyor transfers coal from both the ROM Coal Stockpile and the Coal Washplant to the Primary Crusher Building. The coal passes through the primary crusher, and is reduced to an 8 x 0 inch size (Note: Coal from the longwall typically meets this size consist, and does not require primary crushing). Following primary crushing, the coal is discharged to a 60-inch conveyor belt. This belt feeds the coal from the Primary Crusher Building to the Secondary Crusher Building. Feed to the secondary crusher passes over TR08-65 2.05-32.4 07/08/08