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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division <br />Rationale, Page 3, COG -0850000 Coal Mining General Permit <br />Table III -2a: Effluent Limitations and Monitoring Requirements -Alkaline Drainage, Coal Preparation Plants and Coal <br />Preparation Plant Associated Areas and Western Alkaline Coal Mining (additional requirements apply to Western <br />Coal Mining, See Section III.A.3 of this rationale) <br />Limitations <br />Parameter 30 -Day 7 -Day Daily Rationale Monitoring! Sample <br />Avg. Avg. Max. Frequency Type <br />General Permit Requirements <br />Flow, MGD <br />Report <br />NA <br />Report <br />Discharge Evaluation <br />Continuous/ <br />Instantaneous z <br />Recorder / <br />In-situ 2 <br />pH, s. u. <br />N/A <br />NA <br />6.5-9.0 <br />Water Quality Standards <br />Weekly <br />Grab <br />Oil and Grease, mg/1 <br />N/A <br />NA <br />10 <br />State Effluent Regulations <br />Weekly <br />Visual a <br />Federal Effluent Limitation Guidelines <br />Weekly <br />Grab <br />Total Suspended Solids, mg/l <br />35 <br />NA <br />70 <br />Federal ELG <br />Weekly <br />Grab <br />Total Iron, mg/l <br />Existing Sources (before 5/4/84) <br />3.5 <br />NA <br />7.0 <br />Federal ELG <br />Weekly <br />Grab <br />New Sources (after 5!4/84) <br />3.0 <br />NA <br />6.0 <br />Settleable Solids, m1/1 <br />Report <br />NA <br />0.5 <br />Federal ELG <br />Weekly <br />Grab <br />Site Specific Limitations <br />Total Dissolved Solids, mg/1 ' <br />Report <br />NA <br />Report <br />Salinity Regulations <br />Quarterly ` <br />Grab <br />Total Phosphorus (as P), mg/1 •• <br />Report <br />NA <br />Various <br />Control Regulations <br />Monthly Gra <br />b <br />Total Recoverable Iron, ug/l * * * <br />1000 <br />NA <br />NA <br />Water Quality Standards <br />Weekly <br />Grab <br />Other Pollutants of Concern <br />Various <br />NA <br />Various <br />Water Quality Standards <br />Weekly <br />Grab <br />Whole Effluent Toxicity (WE7) <br />Chronic <br />Stat Diffand <br />IC25 - IWC <br />State Permit Limitations <br />Quarterly <br />3 Grab/Test <br />Acute <br />LC50 > <br />100% <br />State Permit Limitations <br />Grab <br />Footnotes 1-4, ', and •', See Footnotes under Table 111-1 <br />• •' Thus limitation will apply and ivtll substitute for the 30 -day average total iron limit based upon the ELG, when a total recoverable iron standard is applicable to the <br />stream segment. <br />Alternate Limitations For Alkaline Mine Drainage, Coal Preparation and Associated Areas and Western Alkaline Coal <br />Mining - Table 11/-2b contains limitations for any discharge or increase in the volume of a discharge from an above --round <br />alkaline mine (or an underground alkaline mine where the effluent is commingled with other categorical wastewater prior to <br />discharge), caused by precipitation within any 24-hour period less than or equal to the 10 -year. 24-hour precipitation event <br />(or snoivmelt of equivalent volume) Ma <br />y substitute the following limitations for these specific parameters only, subject to <br />burden of proof requirements described in Part 1. B.4 of the permit. <br />Table III -2b: Alternate Effluent Limitations and Monitoring Requirements - Alkaline Drainage, Coal Preparation Plants and <br />Coal Preparation Plant Associated Areas and Western Alkaline Coal Mining (additional requirements apply to <br />Western Coal Mining, See Section III. A.3 of this rationale) <br />Limitations <br />Parameter 30- 7 -Day Daily Rationale <br />Day Avg. Max. <br />Monitoring <br />Frequency t <br />Sample <br />Type <br />Avg. <br />— Federal Effluent Limitation Guidelines <br />Total Suspended Solids, mg/l Report NA Report Federal ELG <br />Weekly <br />Grab <br />Total Iron, mg/1 <br />Existing Sources (before 514,84) Report NA Report Federal ELG <br />Weekly <br />Grab <br />New Sources (after 514,184) Report NA Report <br />Alternate Limitations For Alkaline Mine Drainage, Coal Preparation and Associated Areas, and Western Alkaline Coal <br />Mining - Table III -2c contains limitations for any discharge or increase in the volume of a discharge from an above ground <br />alkaline mine (or an underground alkaline mine inhere the effluent is commingled with other categorical wastewater prior to <br />discharge), caused by precipitation within any 24 -hoar period greater than the 10 -year, 24-hour precipitation event (or <br />snowmelt of equivalent volume) may substitute the following limitations for these specific parameters only, subject to burden <br />of proof requirements described in Part I B 4 of the permit <br />