PERMFILE136566 - Laserfiche WebLink

Home Browse Search

tt'es! Elk Mine analyses after spring runoff each year and where appropriate, update Exhibit 14C. The update • will include an evaluation of the relative change in the factor of safety during the previous year and since the installation of the corrective measures in 1998. A revision including the updated information will be provided to the Division by July 30'" of each year. 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 fee[, and into the bedrock fracture zone below the F-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 the 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. Map 54, 54A, and 54B shows the distribution of sediment control structures at the West Elk Mine. Map 54 and Map 54A identifies 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. Map 1 E, 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. Hvdrologie Studies and Methodoi'o¢v Studies have been made that 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-l, MB-2, and MB-3), ditches and culverts by Memck and Company. This report was submitted to the State Engineer for the approval of [he three 2.U5-28 Revised Jan /996RV03. Revised Nov. 1996PR07, RevsedJan. /997TR79. Revised Jul. 1997TR8? Revised Ocr 1998 TR86: Revised Jun. /999 TR90