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

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COLORADO DEPARTMENT OFPUBLICHEALTHAND ENVIRONMENT, Water Quality Control Division Rationale, Page 2, COG-0850000 Coal Mining General Permit B. Application Dischargers can apply for coverage under this general permit once the permit is issued. Holders of certifications under the administratively extended Coad Mining Permit (COG-0850000) will automatically be transferred to this new general permit. Their coverage will be transferred to the new general permit without a lapse of coverage (i.e. discharging without a permit) and without loss of fee payments. The permittee will have 90 days, from the date of transfer, to comply with any new terms and conditions of this general permit. For all others, the owner or operator of the site shall submit one original completed application and a copy, including a signed certification that the SWMP is complete at least thirty days prior to the commencement of mining activities. III. EFFLUENT LIMITATIONS A. General Effluent Limitations and Monitoring Requirements Numeric effluent limitations are imposed for pollutants that are specific to the discharges covered, and are shown in Tables III-1 through III-6. Some of these limits are based on the EPA Federal Efjluent Guidelines for the applicable point source category and are described below. The certification will state which conditions apply to which outfalls, based on the nature of the discharge. Note that any parameter that is determined to be asite-specific pollutant of concern may be added to the discharge certification. 1. Sur ace Runoffor Non-Coal Minim Related Wastestreams -Table III-1 contains the general limitations and monitoring requirements for wastewater from coal mining sites that are not directly related to mining activities. Table III-I: Effluent Limitations and Monitoring Requirements for Outfalls Comprised of Surface Runoff or Non-Coal Mining Related Waste Streams Limitations Monitoring Sample Parameter 30-Day 7-Day Daily Rationale Frequency l Type ---~~- Avg. Avg. Max. General Permit Requirements----------------------------------------------- Flow, MGD ~~ _ Report NA Report Discharge Evaluation Continuous / 2 Recorder / Instantaneous In-situ pH, s. u. N/A NA 6.5-9.0 Water Quality Standards Weekly Grab Oil and Grease, mg/l N/A NA 10 State Effluent Regulations Weekly Visual j ~_________________~~_____-__---Federal Effluent Limitation Guidelines----------------------------° --- Settleable Solids, ml/1 Report NA 0.5 Federal ELG Weekly Grab Settleable Solids, ml/1 * Report NA Report Federal ELG Weekly Grab ~ ---Site Specific Limitations------ ~ ----------------_________~_- __________ Total Dissolved Solids, mg/1 ** Report NA Report Salinity Regulations Quarterly ° Grab Total Phosphorus (as P), mg/l *** Report NA Various Control Regulations Monthly Grab Other Pollutants of Concern Various NA Various Water Quality Standards Weekly Grab 1 - For a minor facility, as determined by the EPA NPDES Permit Rating Worksheet, all weekly monitoring requirements shall be changed to 2 days per month. 2 -Ifpower is not available, jlow may be measured on an instantaneous basis. Major facilities shall monitor jlow weekly, minorfacilities 2 days /month 3 - If a visual sheen is noticed, a grab sample must betaken and analyzed for oil and grease 4 -Quarterly monitoring shall be prescribed if the limitation is based upon discharge to the Colorado River Basin. If the limitation is based upon agricultural protection, the monitoringfregzrency shall be weekly. * If caused by precipitation within any 24-hour period greater than the 10-year, 24-hour precipitation event (or snowmelt of equivalent volume) ** The TDS limitation will normally apply to discharges in the Colorado River Basin. An evaluation of the discharge will take place upon certification, to see if the facility meets the 1 ton/day or 350 tons/year allowable discharge of salt. If the facility does not meet this requirement, the facility will be required to submit a salinity report docztmenting that achieving this level of discharge is not feasible. See Regulation 61.8(2)(1) for more information. *** The phosphorus limitations apply to discharges to the Dillon Reservoir Wateshed, Cherry Creek Reservoir Watershed, Chatfield Reservoir Watershed, and the Bear Creek Watershed, as defined in Regulation 71, 72, 73 or 74 respectively. The permittee may be required to obtain a phosphorus allocation from the applicable control regzrlation authority prior to certification under this general permit. 2. Alkaline Drainage Coal Preparation Plants and Coal Preparation Plant Associated Areas and Western Alkaline Coal Minin -Tables III-a, III-b and III-c apply to Alkaline Drainage, Coal Preparation Plants and Coal Preparation Plant Associated Areas and Western Alkaline Coal Mining. These tables cover the basic limitations, as well as alternate limitations based upon precipitation events. These categories are subject to 40 CFR Part 434 Subparts B (Coal Preparation Plant and Associated Areas), D (Alkaline Mine Drainage) and F (Miscellaneous Provisions). These limitations also apply to Western Coal Mining Operations. Additional limitations for Western Coal Mining can be found under Section IILA.3 of this rationale. At a minimum, the following limitations may apply as outlined in these subparts.