2015-03-11_PERMIT FILE - C1981038A (2)

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COLORADO DEPARTMENT OFPUBLICHEALTHAND ENVIRONMENT, Water Quality Control Division Rationale, Page 4, COG-0850000 Coal Mining General Permit • Table III-2c: Alternate Effluent Limitations and Monitoring Requirements -Alkaline Drainage, Coal Preparation Plants and Coal Preparation Plant Associated Areas and Western Alkaline Coal Mining (additional requirements apply to Western Coal Mining, See Section III.A.3 of this rationale) Limitations Parameter 30-Day 7-Day Daily Rationale Monitoring Sample Avg. Avg. Max. Frequency Type --------------------------------------Federal Effluent Limitation Guidelines-------------------------------------- Total Suspended Solids, mg/1 Report NA Report Federal ELG Weekly Grab Totallron, mg/l Existing Sources (before 5/4/84) Report NA Report Federal ELG Weekly Grab New Sources (after 5/4/84) Report NA Report Settleable Solids ml/l Report NA Report Federal ELG Weekly Grab 3. Effluent Limitations -Western Alkaline Coal Mining - In addition to the requirements under Part LB.1 above, western alkaline coal mines are subject to 40 CFR Part 434 Subpart H. This subpart applies to alkaline mine drainage at western coal mining operations from reclamation areas, brushing and grubbing areas, topsoil stockpiling areas, and regraded areas, where the discharge, before any treatment has a pH equal to or greater than 6.0; has a dissolved iron concentration less than 10 mg/L; and has a net alkalinity that is greater than zero. The effluent limitations in this subpart apply zrntil the appropriate authority has authorized bond release. a. Sediment Control Plan -The following items apply to those facilities, and specifically those areas outlined above. 1. The operator must submit asite-specific Sediment Control Plan to the permitting authority that is designed to prevent an increase in the average annual sediment yield from pre-mined, undisturbed conditions. The Sediment Control Plan must be approved by the permitting authority and be incorporated into the permit as an effluent limitation. The Sediment Control Plan must identify best management practices (BMPs) and also must describe • design specifications, construction specifications, maintenance schedules, criteria for inspection, as well as expected performance and longevity of the best management practices. 2. Using watershed models, the operator must demonstrate that implementation of the Sediment Control Plan will result in average annual sediment yields that will not be greater than the sediment yield levels from pre-mined, undisturbed conditions. The operator must use the same watershed model that was, or will be, used to acquire the SMCRA permit. 3. The operator must design, implement, and maintain BMPs in the manner specified in the Sediment Control Plan. b. De znitions -The following definitions are specific to this subpart. 1. Brushing and grubbing area means the area where woody plant materials that would interfere with soil salvage operations have been removed or incorporated into the soil that is being salvaged. 2. R~aded area means the surface area of a coal mine that has been returned to required contour. 3. Topsoil stockpilin area means the area outside the mined-out area where topsoil is temporarily stored for use in reclamation, including containment berms. 4. Reclamation area means an area that was previously disturbed as a part of the coal mining operation that is being reclaimed. 4. E flluent Limitations -Post Minin$ Areas and Reclamation Areas -Post-mining limitations may apply to outfalls serving reclamation areas, which have been returned to the required contour and on which revegetation (seeding or plantings work has commenced. Limitations may also apply to post mining underground mine areas. The permtttee may request consideration for change from active mining limitations to post-mining limitations when these conditions have been met. a. Post Mining Reclamation Areas -Tables III-3a and III-b apply to this category, subject to 40 CFR Part 434 Subpart . E (Post Mining Areas). The following limitations apply to reclamation areas. The federal ELG limitations would apply until bond release. If these wastewaters are combined with other waters under Section III of this rationale, then those limitations shall apply. If this wastewater is combined with post mining underground mine wastewater, then the limitations in Section IILD.2 apply to the combined discharge. If this post mining wastewater is separate, then the following limitations apply.