PERMFILE137697 - Laserfiche WebLink

Home Browse Search

West Elk Mrne to erosion. If a small amount of channel erosion does occur over this 300 foot long reach of Lone Pine Gulch, there would be no measurable impact to the North Fork. MCC has installed an energy dissipater at the pipeline discharge location and installed riprap in Lone Pine Gulch, just above its confluence with the North Fork. While the long-term magnitude and duration of discharges to Lone Pine Gulch is not currently known, the dischazge will be limited by the volume of water in the NW Panels sealed sump above the seals. Essentially, the dischazge rate will be controlled by the rate at which water is pumped to the NW Panels sealed sump. Once the Sylvester Gulch pumping system from the NE Panels sealed sump is on line, it will be the primary mine water discharge point. Then the Lone Pine Gulch mine water dischazge point will likely be used only if needed, such as in the case of another large inflow emergency. C~ li Mine Water Treatment - In 1996, MCC experienced difficulty complying with the numeric effluent limit for TSS. In November, 1996, MCC received a letter from the Colorado Water Quality Control Division (CWQCD) which specified that no further TSS permit exceedances due to the B East Mains fault water would be allowed or penalties could be assessed. This was the other major reason MCC began directing the larger mine water inflows to the NW Panels sealed sump in late 1996. During 1996, compounding the problem of increased inflows to the sedimentation ponds was the presence of an unusual colloid. While the source of the colloid is not definitively known, MCC believed that the clay particles may be inherent in the coal seam in the eastern part of the mine. A particle size distribution was performed on the mine water to better understand the nature of the colloidai particles. The colloids aze clay particles with 95 percent of the particles smaller than five microns and 35 percent smaller than two microns. The chemical flocculentslpolymers that had historically been effective did not work on this colloid. After extensive testing by MCC, consultants and chemical suppliers, MCC determined that conventional alum in heavy doses would be the most practical means for meeting the necessary TSS limits. There are significant drawbacks to alum applications in this situation. First, substantial quantities of alum are required. For example, with MB-1 and MB-2R at capacity, approximately 4,000 pounds of alum per week per pond were necessary. The chemical is corrosive and applying it to the sedimentation ponds is difficult and costly (MCC has rented a "hydroseeder' truck to spray on liquid alum). An even lazger concern is the enormous quantity of "floc" that is generated by the alum additions. MCC recognizes that it will be necessary to remove the alum floc that has accumulated in the sedimentation ponds, on a more frequent basis, and this will require a major expenditure each time. Continuing to apply alum in the current mariner on a long-term basis is not feasible. MCC investigated. and evaluated numerous water treatment systems to identify effective, reliable, long-term alternatives for the reduction of TSS. Four technology categories were evaluated; gravity sepazation of solids, batch treating of ponds, chemical treatment, and physical treatment. The technology categories evaluated are summarized below: 2.OS-1 ~ Revised.lrm. 1995 PR06; Revised Nov. 1998 TR80; IN8 PR08