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COf_OR;IDO DEI'•IRT.b1E:\'T OF 1'UL'LICNE.IL"(H.I'tD C:VV(ROrV~41E~7, ll'urrrQuu[rn Cnnrr~~l Urrisrun Ranunulr ;Imendnren[ rb'o. 1 Puce 6. Perrnu No CO-0000221 Z) For snnwmelr ro wmee TSS and rota! iron luniratiur~s, it o necessnrv to demntisnute that dticherge • ucc'urred withal ~$ hours after pond inflow has srupoed To waive sert(enMe snhds !i•r ~~aiun.,, it is neeessrr; to Drove that discharge occurred wuhrir 4,$ hours ajier pond infla:r valuate ~reate.• than dre !0-year, 24-hour event leas snipped. c1 Salinity f7eruintions In canplinnce xith section 61 8(2J(i)/ ojdie CoL>rndo De;cirarve Permit .Svs'rern Regulations. the pennirree shall monitor for corr.! drssolverl solids an a quarterly basis Samples shall be taken at the effluent rlisdiarge points. Salinity requirements are included in Part LB.I e ql the perrnu d) W7tnle Effluent Tn.ricin~ !WET) Tesrine: /n adrhuon to nnuz WET resang jot existing ourfa(fs 002. 003. 005. 006, 010 and 011, and chronic LD'ET testing for erisnng ourjalls 004 m[d 003, acre WET testing is requiredt for new outfalls 012, 013, 014, 016, and 017. See the following discussion jot WET tesnn,q for these outfalls. (Afso see Pnrt L,a 4. of the permit.) !) PurQose of bVET Tesrinq: Z1te Water Quality Control Division has established the use of WET testing as a method jot identifying and controlling toxic discharges from x•astewater trentntent facilities. WET testing is being utilized ns a memo m ensure that there are nn discharges of pnlhrtnnls "in amounts. concentrattorts or combinations which are harmfid to the beneficial uses or toxic to humans, amnmis. plants, or aquatic life" as required by Section 31.11 (1) of rice Basic Standards and Methodologies (or Surface Waters. 2) Instrenm Waste Concentration (/WCI: Where nwnitaring or limitations for WET are deemed appropriate by the Division, chronic instream dihttion as represented by the chronic /LL'C is critical in determining witerher acute or chronic conditions shall apply. For (hose discharges where rite chronic lWC is greater than (>) 9. / `90, chronic conditions apply, where the ILVC is less then or equal to (s) 9. I • acute conditions apply. The chronic lWC is detern[ined using the jollorving equation: IWC = (Facility Flow (FF)/(Stream Chronic Low Flow (annual) + FF)J X 100% Flows and IWC calculations jot outfalls 012, 0I3, 014, 016, and 017 are irrelevant for this determination because, in addition to the IlVC value for determining whether chronic or acute WET resting requirements are applicable, the classification of the receiving stream must be considered. According to the Colnrndo Water Quality Control Division Biomorritorinq Guidance Doaunent dated July 1, 1993, where the receiving water is classified aquatic life, class Z without all ojthe appropriate aquatic life numeric standards, acute WET testing is required, regardless ojdi/tttion. Since the receiving waters jot outfalls 012, 013, 014, 016, and 017 are classified as Class 2 Aquatic Life use, but x~ithout a!I of the appropriate aquatic life numen.'c standards, the Division has determined that acute WET testing is applicable for these outfalls (also see following paragraph). Since segment 12 is classified this way, these five outfalls are subjerr to acute WET testing requirements 3) Acttte LVET Limitations - Ourfalls 012 013. 014 016 and 017: The Division 17ns found that discharges ojpil pumpage. spoils spring water and similar sources horn coal mines at similar sites have exhibited effluent toxicity. Also, toxicity failures have previously occurred jot same ojthe discharges at this facility. On this basis, the Division believes there is reasonable potential for the dischargges frorrt outfalls 012. 013. 0I4. 016, and 0I7 to interfere with attainment of applicable wn(er quality classifications or standards. Because of this, the naue toxicity limit has been incorporated into the permit and becomes effective immediately The perniittee is required to conduct routine moniroring, the resul(s of whrch are m be reported as nit LC,~. If dre LC~p s 100 `7a effluent, tJte permutee is required to conduct dre automatic complimtce schedule as identified in Part LA.4.c. of the permit L