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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division <br />Rationale, Page 5, COG-0850000 Coal Mining General Permit <br />Table Ill-3a: Effluent Limitations and Monitoring Requirements -Post Mining reclamation Areas <br /> Limitadonx Vonttoling Sample <br />Parameter 30-Day i4 7-Day Daily : Rationale 1 <br />Frequencv <br />Type <br /> Avg. 4? Max. <br /> General Permit Requirements <br />Flow, MGD Report NA Report Discharge Evaluation Continuous / <br />Instantaneous` Recorder / <br />In-situ <br />PH, S.U. N/A NA 6.5-9.0 Water Quality Standards Weekly Grab <br />Total Suspended Solids, mg11 30 45 NA State Effluent Regulations Weekly Grab <br />Oil and Grease, mg11 N/A NA 10 State Effluent Regulations Weekly Visual s <br /> Federal Effluent Limitation Guidelines <br />Settleable Solids, mkl Report NA 0.5 Federal ELG Weekly Grab <br /> Site Specific Limitations <br />Total Dissolved Solids, mg11 + Report NA Report Salinity Regulations Quarterly 4 Grab <br />Total Phosphorus (as P), mg/7 •+ Report NA Various Control Regulations Monthly Grab <br />Total Recoverable Iron, ug/1 *** 1000 NA NA Water Quality Standards Weekly Grab <br />Other Pollutants of Concern Various NA Various Water Quality Standards Weekly Grab <br />Whole Effluent Toxicity (WET) <br />Chronic Stat Diff and IC25 > IWC State Permit Limitations Quarterly 3 Grab/Test <br />Acute LC50 > 100% State Permit Limitations Grab <br />Footnotes 1-4, +, **, and*** -See Footnotes under Table III-1 and Table X-2. <br />Alternate Limitations For Post-Mining Reclamation Areas - Table III-3b contains limitations for any discharge or <br />increase in the volume of a discharge from a reclamation area, caused byprecipitation within any 24-hourperiod <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 LB.4 of the <br />permit. <br />Table III-3b: Alternate Effluent Limitations and Monitoring Requirements - Post Mining reclamation Areas <br />Limitations Xfonitorijig .S'umhle <br />Parameter 30-Duv 7-Day Daily Rationale F requeuy , <br />Type <br />Avg- A_g Afai. . <br />Federal Effluent Limitation Guidelines <br />Settleable Solids, m1/1 Report NA Report Federal ELG Weekly Grab <br />b. Post Mining Underground Areas -Table III-4 applies to this category, subject to 40 CFR Part 434 Subpart E (Post <br />Mining Areas). The following limitations apply to underground areas. The federal ELG limitations would apply until <br />bond release. If these wastewaters are combined with other waters under Part LB. 1, then those limitations shall apply. <br />If this wastewater is combined with post mining reclamation area wastewater, then these limitations apply to the <br />combined discharge. If the post mining wastewater is separate, then the following limitations apply. Discharges of mine <br />drainage from underground workings of underground mines which are not commingled with discharges eligible for <br />alternate limitations set forth in this section shall in no event be eligible for the alternate limitations set forth in this <br />section.