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COLORADO DEPARTMENT OFPUBLIC HEALTHAND ENVIRONMENT, Water Quality Control Division <br />Rationale-Page 4, Permit No. CO-0000132 <br />Table <br />Flow, MGD <br />TSS, mg/1 <br />pH, s. u. <br />Oil and Grease, mg/1 <br />TDS, mg/l <br />Design Capacity <br />State Effluent Regulations <br />Water Quality Standards <br />State Effluent Regulations <br />Salinity Regulations <br />Total Residual Chlorine, mg/1 0.071/0.019 d Water Quality Standards <br />* These parameters are subjec! to Alternate Limitation Burden ojProojRequirements, see section VLA.2. c. <br />° 30-day average (This is a design capacity, not a permit limit)/daily maximum <br />Daily Maximum <br />` Minimum-Maximum <br />a 30-day average/datly maximum <br />` 30day average/7day average <br />2. Discussion o~Effluent Limitations <br />a. Oil and Grease: The Relations for Effluent Limitations (Regulation No. 62) include effluent limitah'ons that apply <br />to all discharges of wastewater to State waters. These regulations are applicable to the discharges from the <br />Sanborn CreekMine and Elk Creek Mine WWTF. The pHlimitah'ons specified in the Regulations for Effluent <br />Limitations are not the most stringent and thus are not used as discussed below. <br />b. ~: This parameter is limited by Water Quality Standards as the water quality standards of 6.5-9.0 s.u. range are <br />more stringent than those specked under the Regulations for Effluent Limitations . <br />c. Applicable Federal E1Ruent Guidelines and Standards: The federal guidelines which apply ro this type offacility <br />are found under 40 CFR 434, titled Coal Mining Point Source F,ffluent Guidelines. The limitations which apply are: <br />Table VI-4 -Federal Standards /40 CFR <br />Parameter Limitations <br />30 Day Avg Daily Maz <br />pH, s. u. (minimum -maximum) --15.0 - 9.0-- <br />Total Suspended Solids, mg/1* 35 70 <br />Totallron, mg/1* <br />BAT** 3.5 7.0 <br />NSPS*** 3.0 6.0 <br />Settleable Solids, mU1 * N/A 0.5 <br />* These parameters subject to Burden afProojRequirements, see next section <br />** BestAvailable Technology-applies to those ponds already constructed <br />* ** New Source Performarsce Standards -applies to those ponds constructed after S/4/84 <br />Alternate Limitation Burden ofProofReauirements: In conformance with 40 CFR 434.63, the permittee has the <br />burden of proof when requesting relieffrom total suspended solids (TSS), total iron and/or settleable solids <br />limitations, as appropriate. The intent of this regulation is to afford relief only when needed due to a volume of <br />watergenernted by a speck storm event, it is not intended to be automatically applied to all discharges caused by <br />precipitation, nor to be used to discharge volumes in excess of that generated by the storm event. On this basis, <br />re[iefshall be granted only when necessary and shall not be granted when the permittee has control over the <br />discharge, enabling them to meet the primary limitations. The permittee should endeavor to meet the primary <br />limitations whenever possible. Because manual dewatering can be accomplished as time and conditions permit, all <br />manual dewatering shall be required to meet the primary [imitations. The Division shall determine the adequacy of <br />proof. As part of this determination, the Division shall evaluate whether the permittee could have controlled the <br />discharge in such a manner that primary limitations could have been met. <br />For rainfnll, to waive TSS and total iron limitations, it is necessary to prove thnt discharge directly resulted <br />OI8 <br />Lrtst Revised: 4/28/2004 <br />