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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 III -3a: Effluent Limitations and Monitoring Requirements —Post Mining reclamation Areas <br />Parameter <br />Limitations <br />30 -Day 7 -Day Daily <br />Rationale <br />Monitoring <br />Frequency <br />Sample <br />Type <br />A <br />Avg. Avg. Max. <br />General Permit Requirements <br />Flow, MGD <br />Report NA Report <br />Discharge Evaluation <br />Continuous / <br />Instantaneous i <br />Recorder i <br />In-situ a <br />pH, s. it. <br />N/A NA 6.5-9.0 <br />Water Quality Standards <br />Weekly <br />Grab <br />Total Suspended Solids, mg/1 <br />30 45 NA <br />State Effluent Regulations <br />Weekly <br />Grab <br />Oil and Grease, mg11 <br />N/A NA 10 <br />State Effluent Regulations <br />Weekly <br />Visual 1 <br />Federal Effluent Limitation Guidelines <br />Settleable Solids, ml/I <br />Report NA 0.5 <br />Federal ELG <br />Weekly <br />Grab <br />Site Specific Limitations <br />Total Dissolved Solids, mg/1 • <br />Report NA Report <br />Salinity Regulations <br />Quarterly 4 <br />Grab <br />Total Phosphorus (as P), mg/1 •• <br />Report NA Various <br />Control Regulations <br />Monthly <br />Grab <br />Total Recoverable Iron, ug/1 * * * <br />1000 NA NA <br />Water Quality Standards <br />Weekly <br />Grab <br />Other Pollutants of Concern <br />Various NA Various <br />Water Quality Standards <br />Weekly <br />Grab <br />Whole Effluent Toxicity (WE7) <br />Chronic <br />Stat Diff and IC25 > IWC <br />State Permit Limitations <br />Quarterly <br />3 Grab%Test <br />Acute <br />LC50 > 100% <br />State Permit Limitations <br />Grab <br />Footnotes 1-4, •, • •, and • •• -See Footnotes under Table 1114 and Table 111-2 <br />Alternate Limitations For Post -Mining Reclamation Areas - Table 111-3b contains limitations for any discharge or <br />increase in the volume of a discharge from a reclamation area, caused by precipitation within any 24-hour period <br />greater than the 10 -year, 24-hour precipitation event (or snowmen of equivalent volume) may substitute the following <br />limitations for these specific parameters only, subject to burden of proof requirements described in Part I B.4 of the <br />permit. <br />Table III -3b: Alternate Effluent Limitations and Monitoring Requirements — Post Mining reclamation Areas <br />Limitations <br />Parameter 30 -Day 7 -Day Daily Rationale Monitoring Sample <br />Avg. Avg Max. Frequency Type <br />Federal Effluent Limitation Guidelines <br />Settleable Solids, ml/1 Report NA Report Federal ELG Weekly Grab <br />b. Post Minine Underground Areas -Table 111-4 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 I. B 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 <br />