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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Qunlirv Cone of Diri.cion <br />Rationale -Page 9, Permit No. CO-0038776 <br />2. Cnlculntion of Wnrer Ounlirv Based Effluent Limhnrions <br />A mass balance equation was used ro determine the effluent mncentrarions that would nor violate rlre allowable <br />in-stream concentrations drflned by the water quality standards (except in the case ojpH, where dre limirnriorec are <br />set directly from stream sraru(ards ar e,[JIuent regulations without using a mass balance approach). The rrrnrc <br />balance equation is: <br />ryt = M3Qr - MrQt . <br />Qt <br />Where: <br />Qr = Upstream low flow (1 £3 or 30E3J from Part I11.B.2 <br />Qr =Average daily e,Qluent flow !design capacity) <br />Qf = Combined downstream flow (Qt + QtJ <br />Mr = Upstream background pollutant concentration from !l1.B.1 <br />Mz = Unknown; Maximum allowable effluent pollutant concentration calculated using macs balance equation <br />Mj = Maximum downstream nllown6le pollutmtt concentration (stream standard) <br />Because of the mmhenmrical re!mionship between flow, pollutant concentration mrd pollurnru mncc, crnuernrnriou <br />limitations rnfculnted ucnrg this method implicitly limit insrream pottmnrrr mass ro the maximum nllorvahfe Icref. <br />Also, only flow oral concenrrntion limitations need ro be specified in the permit. Mrus limirnrions are nm requir-erl. <br />A summary of the mass balance rn/culnrions (ijnnyJ is shown and discussed in Vl.A.3. <br />3. Discussion of Ej/luent Limirnrions <br />nJ Reeulnriau (or Effluent Limimrions: The Regulations jot Effluent Limitations (10. LOJ, apply m the <br />corn~emionnl po!lutnms. For this facility the limitmions for OP[ and Grease are baser! on this regulmian. <br />bJ Anplicnble Federal Effluem Guidelines and Smndnrds: The federal guidelines which apply ro this n~re ojfncilin• <br />are found under 40 CFR 434, titled Effluent Guidelines (or Coa! Mirrirre. The limirerinn.c which npph• nrer <br />Table VI-5 -- Federal Standards (40 CFR 434) <br />Parameter <br />Limitatioas <br />30 Day Avg Dnih~ Max <br />pH, s. u. (minimum - maxitrtumJ ---6.0 - 9.0--- <br />Torn! Suspended Solids, ml;/P* 35 70 <br />Total Iron, mg/P* 3.5 7.0 <br />Setrlenble Solids, mf/P* N/A 0.5 <br />• 7lrrsr paramarrs are subjen ro Bunirn of Proof Requirrmrna, see nut srrnon <br />Alternate Limitation Burden of Proof Renuirementr: !n cot jormmrce with 40 CFR 434.63, the permiuee has the <br />burden ojproojwhen seeking relief from total suspended solids (-!'SSJ, torn! iron and/or seulenbJr .rnfidc (SSJ <br />limitations. Discharges frora omjalk 007, Oll and 012 are not eligible jot this exenrptioa. OulfalLr 002 and <br />004 are eligible for reliejfrom 7SS, torn/ iron acrd SS; however, the majority of the loading fi au any dicdmrge <br />has ro consist ojstorm runoj'Jfor the reliejro be nvrtilnble. The permittee will need to show that exceedeace of <br />the applicable Iimirarions wru~ mused by precipitation and not mine water, through n compnri.cmr of the loading <br />from each source. The remaining permitted ourjnlls (005, 006, 008 oral 009) are eligible far relief from TSS, T. <br />/mn and SS m all rimer since Duly surface runoff (raw water jot aurfall 006) di.cchargec are nurhn+'iced from <br />these outjnllc. <br />