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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division <br />Rationale, Page 7, COG -0850000 Coal Mining General Permit <br />Alternate Limitations For Acid Or Ferruginous Mine Drainage (except as covered below under coal refuse piles or <br />mountaintop removal) — Table 111-5b contains limitations for any discharge or increase in the volume of a discharge from an <br />above ground mine (or underground 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 2 -year, 24-hour precipitation event <br />(or snowmelt of equivalent volume) may substitute the following limitations for these speck parameters only, subject to <br />burden of proof requirements described in Part I B 4 of the permit. <br />Table III -5b: Alternate Effluent Limitations and Monitoring Requirements — Acid or Ferruginous Mine Drainage <br />Limitations <br />30 -Day <br />Parameter <br />Limitations <br />30 -Day <br />7 -Day <br />Daily Rationale <br />Monitoring' <br />Frequency <br />Sample <br />Type <br />Avg. <br />Avg. <br />Avg. <br />Max. <br />Frequency <br />Type <br />Federal Effluent Limitation Guidelines <br />Total Suspended Solids, mg1l <br />Report <br />NA <br />Report Federal ELG <br />Weekly <br />Grab <br />Total Manganese, mg1l <br />Report <br />NA <br />Report Federal ELG <br />Weekly <br />Grab <br />Total Iron, mg/7 <br />Grab <br />Total Iron, mg11 <br />Existing Sources (before 5/4/84) <br />Report <br />NA <br />70 Federal ELG <br />Weekly <br />Grab <br />New Sources (after 514184) <br />Report <br />NA <br />Report <br />New Sources (after 514184) <br />Report <br />Settleable Solids, ml/! <br />Report <br />NA <br />0.5 Federal ELG <br />Weekly <br />Grab <br />Alternate Limitations For Acid Or Ferruginous Mine Drainage (except as covered below under coal refuse piles or <br />mountaintop removal) — Table 111-5c contains limitations for any discharge or increase in the volume of a discharge from an <br />above ground mine (or underground mine where the effluent is commingled with other categorical wastewater prior to <br />discharge), caused by precipitation within any 24 hour period greater than the 2 -year, 24-hour precipitation event, but less <br />than or equal to the 10 year, 24-hour precipitation event (or snowmelt of equivalent volume) may substitute the following <br />limitations for these speck parameters only, subject to burden of proof requirements described in Part I.B.4. <br />Table III -5c: Alternate Effluent Limitations and Monitoring Requirements —Acid or Ferruginous Mine Drainage <br />Parameter <br />Limitations <br />30 -Day <br />7 -Day <br />Daily <br />Rationale <br />Monitoring' <br />Sample <br />Avg. <br />Avg, <br />Max. <br />Frequency <br />Type <br />Federal Effluent Limitation Guidelines <br />Total Suspended Solids, mg1l <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />Total Manganese, mg1l <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />Total Iron, mg11 <br />Existing Sources (before 514184) <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />New Sources (after 514184) <br />Report <br />NA <br />Report <br />Settleable Solids, mill <br />Report <br />NA <br />0.5 <br />Federal ELG <br />Weekly <br />Grab <br />Alternate Limitations For Acid Or Ferruginous Mine Drainage (except as covered below under coal refuse piles or <br />mountaintop removal) — Table 111-5d contains limitations for any discharge or increase in the volume of a discharge from an <br />above ground mine (or underground mine where the effluent is commingled with other categorical wastewater prior to <br />discharge), caused by precipitation within any 24 hour period greater than the 2 -year, 24-hour precipitation event, but <br />greater than the 10 -year, 24-hour precipitation event (or snowmelt of equivalent volume) may substitute the following <br />limitations for these specific parameters only, subject to burden of proof requirements described in Part L 8.4. <br />Table III -5d: Alternate Effluent Limitations and Monitoring Requirements —Acid or Ferruginous Mine Drainage <br />Parameter <br />Limitations <br />30 -Day <br />7 -Day <br />Daily <br />Rationale <br />Monitoring' <br />Frequency <br />Sample <br />Type <br />Avg. <br />Avg <br />Max. <br />Federal Effluent Limitation Guidelines <br />Total Suspended Solids, mg1l <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />Total Manganese, mg1l <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />Total Iron, mg.l <br />Existing Sources (before 514.84) <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />New Sources (after 5/484) <br />Report <br />NA <br />Report <br />Settleable Solids, mill <br />Report <br />NA <br />Report <br />Federal ELG <br />Weekly <br />Grab <br />