2009-09-03_REVISION - C1980007 (3)

Home Browse Search

West Elk Mine In the spring of 1999, MCC will drill two horizontal holes from the surface, at the abandoned main mine site substation, to intercept small sumps in the F-Seam to drain the water that accumulates in these sumps. The water that accumulates in these sumps is primarily surface water and near surface groundwater that infiltrates through the colluvium above the F-Seam and into the F-Seam workings. Once the water is in the sump, it then infiltrates through the F-Seam floor and into the unstable surface soils within the main mine site landslide. It is important that water sources to the surface soils be controlled in order to improve the local and global stability. These two holes are a test to determine if this method of draining the sumps is feasible. These sumps are located near the main F-Seam portals. They are not part of MCC's mine water handling system. These sumps have not been nor will be used to handle a large inflow event. The sumps are too small and if they overflow, they will flow into the belt and travel ways. Drain A will be drilled approximately 1,100 feet and into the floor of one of the main collection sumps. Drain B will be drilled approximately 1,400 feet, and into the bedrock fracture zone below the 17- Seam sumps. If the holes are successful, MCC estimates that approximately 22 gpm will flow from the two holes and into pond MB-1. If the holes are successful, MCC will permit and construct additional drains that will remain upon final reclamation. In addition, MCC will update Exhibit 14c to include these drains and evaluate them for the final reclamation plan. (4) Ponds, Impoundments, and Diversions During the course of construction and operation of the mine facilities at West Elk Mine, every effort is made to minimize water pollution. It is MCC's intent to discharge water from sediment ponds, Small Area Exemptions, and from the mine in compliance with all applicable effluent limitations. To fulfill this commitment, all surface drainage from the affected mine area is collected and treated prior to being discharged from the permit area. All surface runoff from undisturbed areas is directed away from the affected mine area through diversion channels. Maps 54, 54A, and 54B show the distribution of sediment control structures at West Elk Mine. Map 54 and Map 54A identify the sub-watershed drainage basins, tributary drainage basin information, and ditch/culvert layouts in conjunction with the main surface facilities area and Lone Pine Gulch, respectively. Maps 1E, 2E and 3E in Exhibit 66 identify the watersheds in the Sylvester Gulch Facilities Area. Map 54B shows the ditch and culvert locations in conjunction with the Sylvester Gulch Facilities Area. The following sections deal with each specific hydrologic protection measure. Hydrologic Studies and MethodolM i Studies have been completed to estimate the peak runoff and flood volume for storms having specific recurrence intervals for the West Elk Mine area. Exhibit 44 is the report used in the design of the original sedimentation ponds (MB-1, MB-2, and MB-3), ditches and culverts by Merrick and Company. This report was submitted to the State Engineer for the approval of the three sedimentation ponds MB-1, the original MB-2, and MB-3, and the freshwater pond, FW-1. Approval was received on February 3, 1981, and is included in Exhibit 45. Exhibit 66 contains the new designs for ponds MB-2R and MB-3. The Exhibit 43 and Exhibit 44 designs are no longer valid for these ponds. Exhibit 66 contains an as-built drawing that reflects the addition of a dike in the pond to create a north and south cell. However, the drawings included in Exhibit 43 do accurately reflect other structures associated with MB-1 (i.e., the primary and emergency spillways). Exhibit 66 also contains the design information for SG-1 located at the Sylvester 2.05-29 Revised June 2005 PRIO, Rev. January 2006, Rev. March 2006; Rev. April 2006 PRIG, May 2006 PRIG; Rev. January 2009 MR-350