2021-08-06_PERMIT FILE - C1982056A

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For intermittent discharge, which is limited to periods of high flow in Fish Creek, TC can discharge mine water which has been treated to reduce suspended solids, and meet applicable effluent standards. Under these conditions, treatment is limited to metered injection of a flocculant, which causes the suspended solids to drop-out in the existing treatment cells. The polymer flocculant will be metered into the flow at a rate at which the flocculant will be effective in settling the coal fines while minimizing any residual in the discharge. Flocculant use has been reviewed and approved by both WQCD and CPW, as documented in Exhibit 49G. Because much of the iron in the mine water is associated with the solids, this treatment approach is also effective in significantly reducing iron levels in the resulting discharge. The flocculant is delivered in poly totes, which are housed in the existing electro -coagulation building, and the flocculant is injected by a metering pump directly into the input flow line prior to the existing mixing tank. Under agitated flow conditions in the mixing tank, the flocculant mixes with the inflow water and then reacts with the suspended solids to form flocs, which settle -out in the treatment ponds. Similar to operation of the electro -coagulation system, the treatment ponds are monitored and accumulated sediments cleaned -out on an as -needed basis to assure continued effective operation of the system. It is anticipated that this treatment approach will require more frequent pond clean-out. A treated product line discharges from the EC water tank to the first settling pond, with the treated water routing through the baffled 3 -cell treatment ponds to assure adequate retention time to allow settlement of the agglomerated solids prior to discharge. In order to handle both normal discharge and any potential overflow from the treatment settling ponds, a 200 -foot 12 -inch PVC pipe is attached to the discharge culvert from the third and final treatment pond. From the third treatment pond, treated mine water can be transferred to either the Fish Creek/Barricade Chamber or the new Fish Creek/Area 1 Pit transfer pipelines, or can be discharged to Fish Creek at Outfall 115 (subject to emergency discharge provisions or seasonal limitations). Installation of remote monitoring equipment at sites upstream and downstream of the Borehole discharge point, and at the effluent of the treatment pond, as shown on Map 13a, provide a more efficient means for monitoring the water quality in Fish Creek. Automated sample results, along with system operating parameters are relayed to TCC's Administration Building where they can be reviewed. Current information is, therefore, available for regulating the treatment process at the borehole facility. TC may install additional monitoring equipment in the ponds to further enhance the treatment process. The Fish Creek/Area 1 Pit Transfer Pipeline will be 12 -inch welded HDPE pipe, buried approximately 5 feet deep within existing pipeline and road corridors, as shown on Map 24 (Sheet 3/3). The approximately 16,900 foot pipeline will cross under Routt County Road 27 (bored under), Haulroads B-1 and C and the Batch -Weigh Haulroad, Foidel Creek (at an existing creek crossing), and the overland conveyor. Pipeline construction will involve removing and temporarily windrowing soil materials along the edge of the pipeline corridor; trenching and temporary placement of the excavated material on the opposite side of the trench; bedding, placement, connection, and testing of the pipeline; controlled backfilling and compaction of the excavated material over the pipeline; and replacement, grading, and reseeding of the soil material over pipeline disturbance areas. Access manholes may be established along the pipeline route for inspection and maintenance purposes. Soil materials will be replaced following completion of pipeline installation. Reseeding of the disturbed areas will be completed during the first appropriate planting period following soil material replacement. In February 2016, an undetected blockage in the pipeline between the Fish Creek Mine Dewatering Well and the Electro -Coagulation Building caused a pipe joint in the well -head to fail and the pumped material to build-up in the vertical culvert around the well -head and overflow, resulting in an accidental discharge of a water/coal fines mixture. At the time the accident happened, the initial inspection indicated a limited discharge volume and that any deposition of coal fines was confined to the immediate area of the well -head and an upper bench area. There was significant snow -cover at the time, and it was difficult to assess the extent of any further movement of coal fines under the snow. Once the snow melted in the spring, it was discovered that the coal fines had moved further than originally thought, and TC placed wattles just beyond the limit of the visible coal fines to prevent them from moving any further, with the intent of cleaning up any coal fines deposition once the ground dried - out. During a CDRMS Inspection in May 2016, the area was inspected and the CDRMS Inspector issued a notice of Violation (NOV CV -2016-001). Consistent with both the original intent. and applicable NOV abatement requirements, TC proposes to cleanup any significant accumulation of coal fines which could adversely impact vegetative growth or which represents a reasonable potential source for sediments which could affect runoff water quality. MRI 6-299 2.05-50.3 06/16/16