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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division <br />Amendment No. 4, Rationale -Page 2, Perniit No. CO-0027154 <br />3. Numeric Standards: The complete list of standards which have been assigned in accordance with the above <br />classifications can be found in 3.3.0, Classificatiorts and Numeric Standards for the Upper Colorado River <br />Basin (5 CCR 1002-8), as amended December 11, 1995. The standards whit!: may be impacted by this <br />discharge follow. <br />Physical and Biological <br />pH 6.5 - 9.0 s. u. <br />Metals <br />Iron (Fe), Total Recoverable = I.0 mg/[ (chronic) <br />Manganese (Mn), Total Recoverable = I.0 mg/l (dtronic) <br />Copper (Cu), Dissolved = TVS (acute and chronic) <br />Silver (Ag), Dissolved = TVS (acute) <br />Table Value Standards -standards for these metals are based upon equations found in Table 111 of 3.1.0, T7te <br />Basic Standards and Methodologies for Surface Water. <br />B. Receiving Water Data <br />1. Stream Low Flow: The flows which will be used to calculate effluent limitations are acute flows, Ntose that <br />occur for one day every Three years (IE3), or chronic, those that occur for thirty days every three years <br />(30E3). These flows have beers determined for Foidel Creek by the Water Quality Control Division and are <br />si:owr: below. <br />Table IV-1 -- Acute and Chronic Low Flows <br />Acute Chronic <br />Annual 0 0 <br />V. TERMS AND CONDITIONS OF PERMIT <br />A. Determination of Effluent Limitations <br />1. Effluent Limitations: In developing suitable effluent limitations, the Division taus! review all applicable <br />standards and regulations and apply those w/rich are more stringent. This review includes, but is not limited <br />to: the water quality standard based effluent limitations, federal guidelines and standards (40 CFR Subchapter <br />N) and State Effluen! Regulations (10.1.0). Such a review has beets done for this faci[iN. The following <br />limits will apply, as indicated in Table V-1. The basis for these limitations follows. <br />Table V-1 -- Effluent Limitations for Outfall 020 <br /> Discharge Limitalions <br /> Maximum Concentrations <br />Parameter 30-Day Avp. Daily Max. Rationale <br />Flow, MGD Report Report Design Capacity <br />TSS, mglP 35 70 Federal Effluent Guidelines <br />TR /ton, mg/P I.0 Report Water Quality Standards <br />TR Manganese, mgP Report Report Water Quality Standards <br />PD Copper, rag/P 0.073 0.130 Water Quality Standards <br />PD Silver, mg/P Report 0.079 Water Qua[iry Standards <br />Oi[ and Grease, mg/P N/A /0 State Effluent Regulations <br />pH, s. u. (Minimum- N/A 6.5-9.0 Water Quality Standards <br />Maximum) <br />