2024-04-25_PERMIT FILE - C1982056A

Home Browse Search

• Continuous readings from an ash analyzer on the main underground production coal conveyor determine whether the production flow on the slope conveyor is routed to the Run-of-Mine (ROM) Coal Stockpile or the Low—Quality Coal Stockpile by the flop-gate at the discharge of the slope conveyor. Since the new Washplant is designed to process a significant portion of the ROM coal flow, the ash cut-off threshold for designation as low-quality coal was increased. This change results in an increase in the percentage of coal routed to the ROM Stockpile and a reduction in percentage to the Low-Quality Coal Stockpile. • The coal-handling system for the low-quality coal was simplified to eliminate the flex-tooth crusher, one intermediate conveyor, and the two associated transfer points • The tailpiece for the existing Overland Conveyor was moved to the west and the belt shortened by approximately 700 feet to accommodate the elevated belt from the ROM Stockpile reclaim system to the top of the new Screening/Crushing Building. Belt speed was increased to accommodate a feed rate of 2,200 tph(12.OMM tpy) • The thickener overflow sump for Washplant I was eliminated and replaced with piping to carry thickener overflow to the larger overflow sump constructed for Washplant II • The primary and secondary crushers, and stoker coal and coal sampling systems in the BOB area were removed and the associated chute-work modified to allow direct pass-through of the product coal stream, since screening, crushing, and sampling will now occur in the Washplant 11 area. The associated Primary Crusher, Secondary Crusher, and Sampling buildings were retained, along with utilities and dust-control equipment to address potential air emissions from coal-handling and transfer points. In 2019 a new Thickener Tank installation is planned. To accommodate for larger wash volumes in the wash plant the a 90 foot diameter Thickener tank will be installed supported by a concrete pad and approximately four feet of devised compacted fill that replaced the existed soil material. To allow for sufficient room on the west side of the wash plant facilities pond D will be modified and slightly reduced in size. The existing material will be excavated out and new suitable material will be placed on the west side of the washplant facilities for a suitable platform for the new Thickener Tank. A Pre-settlement sump will be installed between the tank and Pond D to help catch any sediment leaving the wash plant facilities.The smaller Pre-sump will allow for more consisted sediment control and reduce the amount of sediment that tends up in Pond D. Configurations can be seen on Map 24 (Sheet 1/3) and design drawings in Exhibit 49K,Washplant II Design Drawings. The following sections describe the construction and operation of the various components of the new Washplant II complex. Facility locations, configuration, and operating relationships are shown by the Freshwater Systems and Surface facilities Map, Map 24 (Sheet 1/3), and the design drawings and process flow diagrams included in Exhibit 49K, Washplant II Design Drawings. The entire Washplant II area was disturbed by soil pre-strip activities associated with the previous surface mining activities,therefore,no soil material remained in this area. Drainage from and through this area is controlled by the existing Sedimentation Ponds D and E. Due to changes in site topography resulting from construction grading activities,the following drainage modifications were necessary: • Ditch D-2 was relocated to the south, paralleling the Refuse Haulroad, two culverts were added under the Washplant 11 yard-area access, and the eastern inlet to Sedimentation Pond D was shifted to the south and west. Contributing watershed areas and conditions did not change significantly, ditch and culverts sizes were maintained, and ditch condition and configuration were improved, therefore, revised drainage calculations were not necessary. • Washplant construction would encroach on the existing Pond D emergency spillway, so the spillway was relocated to the center of the Pond D embankment, near the principal spillway. This location also improves pond function by increasing the distance between the pond inlets and emergency spillway and improving routing. • In 2018 the installation of the new Thickener Tank required modification to be done to Pond D. The Pond will be reduced on the east side to allow for enough room for the Thickener tank installation along with a pre-sump installation. To better manage the sediment that drains from the washplant area, a pre-settlement TRI 9-93 2.05-32.3 03/05/19