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

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COLORADO DEPARTMENT OF PUBLIC HEALTHAND ENVIRONMENT, Water Quality Control Division Rationale, Page 3, COG-0850000 Coal Mining General Permit Table III-2a: 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 Monitoring Sample Parameter 30-Day 7-Day Daily Rationale Frequency 1 Type Avg. Avg. Max. ---------------------------------------General Permit Requirements--___________________________________~___ Flow, MGD Report NA Report Discharge Evaluation Continuous / 2 Instantaneous pH, s. u. N/A NA 6.5-9.0 Water Quality Standards Weekly Oil and Grease, mg/1 N/A NA 10 State Effluent Regulations Weekly --------------------- F d l E Li i i id G li ---------------- - e era ffluent m tat on u e nes----------------------------- ---------___ Total Suspended Solids, mg/1 35 NA 70 Federal ELG Weekly Totallron, mg/Z Existing Sources (before S/4/84) 3.5 NA 7.0 Federal ELG Weekly New Sources (after 5/4/84) 3.0 NA 6.0 Settleable Solids, ml/l Report NA 0.5 Federal ELG Weekly _____~-___~_____~_____-__~_____Site Specific Limitations_____ __~_____M__~_~____~ ____~ Total Dissolved Solids, mg/l * Report NA Report Salinity Regulations Quarterly a Total Phosphorus (as P), mg/Z ** Report NA Various Control Regulations Monthly Total Recoverable Iron, ug/Z *** Other Pollutants of Concern Whole Effluent Toxicity (WET) Chronic Acute 1000 NA NA Water Quality Standards Various NA Various Water Quality Standards Stat Dff and IC25 > IWC State Permit Limitations LC50 > 100% State Permit Limitations Weekly Weekly Quarterly Recorder / In-situ a Grab Visual 3 Grab Grab Grab Grab Grab Grab Grab 3 Grab/Test Grab Footnotes 1-4, *, and **, See Footnotes under Table III-1 *** This limitation will apply and will substitute for the 30-day average total iron limit based upon the ELG, when a total recoverable iron standard is applicable to the stream segment. Alternate Limitations For Alkaline Mine Drainage, Coal Preparation and Associated Areas and Western Alkaline Coal Mining -Table III-2b contains limitations for any discharge or increase in the volume of a discharge from an above , r„~ ound alkaline mine (or an underground alkaline mine where the effluent is commingled with other categorical wastewater prior to discharge), caused by precipitation within any 24-hour period less than or equal to the 10-vear, 24-hourprecipitation event (or snowmelt of equivalent volume) may substitute the following limitations for these specific parameters only, subject to burden of proof requirements described in Part I.B.4 of the permit. Table III-2b: 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 IILA.3 of this rationale) Limitations Parameter 30- 7-Day Daily Rationale Monitoring Sample Day Avg. Max. Frequency 1 Type Avg. ____w_________w_~_________~Federal Effluent Limitation Guidelines--_______w_~_~_ w______________ Total Suspended Solids, mg/l Report NA Report Federal ELG Weekly Grab Totallron, mg/l Existing Sources (before S/4/84) Report NA Report Federal ELG Weekly Grab New Sources (after S/4/84) Report NA Report Alternate Limitations For Alkaline Mine Drainage, Coal Preparation and Associated Areas, and Western Alkaline Coal Mining -Table III-2c contains limitations for any discharge or increase in the volume of a discharge from an above rind alkaline mine (or an underground alkaline mine where the effluent is commingled with other categorical wastewater prior to discharge), caused by precipitation within any 24-hour period greater than the 10-vear. 24-hour precipitation event (or snowmelt of equivalent volume) ~ substitute the following limitations for these specific parameters only, subject to burden of proof requirements described in Part I.B.4 of the permit.