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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division Rationale - Page 10. Pex~it No. CO-0032115. VI. TERMS AND CONDITIONS OF PERMIT 1. Water Quality Standard Based Effluent Limitations: a) pH: In the case of pH, the limits are set directly from stream standards, with an allowable range of 6.5-9.0 s.u. For discharge points 001, 002 and 005, a variance to allow a range of 6.5-9.5 s.u. during the months of June through September is included. See Discussion, Section V.B. 2. Applicable Federal Effluent Guidelines and Standards: The federal guidelines which apply to this type of facility are found under 40 CFR 434, the Coal Mining Point Source Category. The limitations which apply are: Table VI-4 - Federal Standards Avg, of Daily Values Parameter for 30 Consecutive Days Daily Maximum T. Suspended Solids, mg/1 (BPJ of BCT, NSPS) 35 70 Total Iron, mg/1 (NSPS) 3.0 6.0 Total Iron, mg/1 (BAT) 3.5 7.0 Settleable Solids, ml/1 (Precip. Events) NA 0.5 The above federal limits are from Subpart D of 40 CFR 434, Alkaline Mine Drainage, Best Available Technology (434.43) and New Source Performance Standards (434.45) and Subpart F, Miscellaneous Provisions, Effluent Limitations for Precipitation Events (434.63). Discharge points 001, 008 and 010 are existing sources, and the discharge consists only of surface runoff. Therefore, the BAT and BPJ of BCT limits apply, as well as the Effluent Limitations for Precipitation Events. Discharge points 012, 013 and 014 are new sources, and discharge surface runoff only. Therefore, the NSPS limits apply, as well as the Effluent Limitations for Precipitation Events. Discharge points 002, 003, 005, 006, 009 and 011 are existing sources, and may co¢tain mine dewatering and/or spoil springs water. Therefore, the BAT and BPJ of BCT limits apply. iy .