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{:OLORADO DEPARZMEM OF PUBLIC HEALTH AND ENVIRONMENT; Water Quality Control Division Rationale -Page 11, Permit No. CO-0045161 2. Discussion o,~Efi`luent Limitations: a) Reculatians for Effluent Limitations: The Regufations for Effluent Limitations Regulation No. 62 (S CCR 1002-62), apply to the conventional pollutants. For this facility the limitations for Oil and Grease are based ors this regulation. b) ~plicable Federal E,~luent Guidelines and Standards: Zhe federal guidelines that apply to this type of facility are found under 40 CFR 434, titled Coal Mining Point Source Effluent Guidelines. The limitations that apply follow. -able VI-3 -Federal Standards (40 CFR Parameter;::.:...: ::..::..::.: ;..: : Limitations .:: ...... 30 Ddy:AvR :...: :: ' ... Dai1p Mar-: `.;::'.: :.:.,.:.: pH, s. u. (minimum -maximum) . --6.0 - 9.0--- Total Suspended Solids, mg/P' 35 70 Total Iron, mg/P* BAT** 3.5 7.0 Settleable Solids, mP/P" N/A 0.5 * These parameters subject to Burden of Proof Requirements, see next section ** Best Available Technology -applies ro those ponds already constructed Alternate Limitation Burden of Proof Requirements: Irt conformance with 40 CFR 434.63, the permittee has the burden of proof when requesting relief from total suspended solids (TSS), total iron and/or settleable solids limitations, as appropriate. The intent of this regulation is to afford relief only when needed due to a volume of water generated by a specific storm event; it is not intended to be automatically applied to all discharges caused by precipitarion nor to be used to discharge volumes in excess of that generated by the storm event. On this basis, relief shall be granted only when necessary and shall not be granted when the permittee has control over the discharge, enabling them to meet the primary limitations. The permittee should endeavor to meet the primary limitations whenever possible. For ponds with automatic dewatering structures, only discharges through these structures are eligible for the exemption. All mantra! dewatering of ponds that are equipped with automatic dewatering systems must meet TSS and total iron limitations. If a pond has only manual dewatering capability (no riser pipes or other automatic dewarering systems), relief is available only to the extent required to regain necessary capacity required by regulations. Additional discharge flow shall meet primary limitations. The Division shall have final atuhoriry in determining whether relief is granted. Discharges from outfalls OOla, 002a, 003a, 004a, OOSa, 006a, 007a, 008a, 009a and OIOa are eligible for this exemption; outfalls 0026, 0046, 0076, 0086, 0096 and OIOb are not eligible for this exemption. Eligibility at outfalls 004a, 007a, 008a, 009a and OIOa is subject to demonstration that outfalCs 0046, 0076, 0086, 0096 and OIOb comply with limitations in I.A.I. b. at time of discharge to demonstrate that surface runoff caused the exceedence of primary limitations. All discharges shall be achieved in accordance with applicable state laws. Documentation that the treatment facifities were properly operated and maintained prior to and during the storm event shall be submitted with any request for relief as an attachment to the Discharge Monitoring Report (DMR} for the appropriate period, and the Division shall determine the adequacy of proof. As pan of this determination, the Division shall evaluate whether the perminee could have controlled the discharge in such a manner that primary limitations could have been met, whether proper sediment storage levels were maintained and the ponds had sufficient water and sediment capacity for the storm event plus other relevant factors. Weather station data may be appropriate for rainfall.