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COLOR,-I00 DEPARTrLIErVT OF PUBLIC HC•.ILTH .AND ErWIRO~VMF_rVT, bVurer Qunliry Connul Drrtsiun Rmiunale Amenrlrrient No 1 Page h, Permit No CO-000022/ 2) For snowrnelt, to wave TSS and !am[ iron limimtmns. a is necessary ro demonstrate that discharge • occurred within 4R hours nfier pond inflow has stopped To waive settleable solids lite~'criun.,, i! is necessary to prove that discharge occurred rwthin 48 hours after pond inflow volume greater d:an dte l0-year, 24-hour event Iris snipped. c) Salinity Reculntioris. !n crnnpliance with section 6/.3(2)(q) of the Colorado Discharge Perrnu S sv rem ~ulntions the pernrittee shall monitor jot total dissoh~ed solids on a quarterly basis. Samples shall 6e taken at the ejfluent rlischnrge points. Salinity requtrements are inchtded in Pan !. B. 1. e of dte permit. d) Wimle Effluent Tozrcit}' lWET) Testing: In addition m noire 6VET testing jot existing oulfnlls 002, 003. 005, 006, 010 and 011, and chronic 6VET testing jar e.risting att(alls 004 and 008, nitre WET testing is required jot new outfalls 012, 013. 014, 016. mtd 017 See the following discussion jot WET testing jot these ottfalls. (Also see Pnrt LA.4. of the perm«.) 1) Purpose aj WET Testing: The Water Quality Control Division has established rite use of LVET testing as a method jot iderttifyirtg and controlling toxic discharges from wastewater trentnrent facilities. WET testing is being utilised as a meats to ensure that there are no discharges ojpollutnnts "in amounts. concentrations or corrtbinntions which ore hnnrifid m the beneficial uses or toxic to hunrnns, animals. p(nnu, or aquatic life" ns required by Section 31.11 (I) of the Basic Stnndnrds and blethodoloeies for Sur(nce Waters. 2) lnstrenm Waste Conceruration (/WC): Where monitoring or limitations for WET ore deemed appropriate by the Division, c/tropic instream dilution as represented by the chronic 1WC is critical in determining whether acute or chronic cartditions shall apply. For those discharger where the chronic IWC is greeter than (>) 9. / %, chronic conditions apply, where the IWC is less than or egunl to (s) 9.1 • acute conditions apply. The chronic /WC is determined using the jollowing eyttatiun: lIVC = [Facility Flow (FF)/(Stream Chronic Low Flow (annual) + FFJ/ X 100% Flows artd IWC calculations jot outfalls 0I2, 013. 014, 016, and 017 are irrelevau jar this determination because, in addition to the (WC value for determining whether chronic or acute WET testing requirements are app[icnble, the classification of the receiving stream roust be considered. According to the Calorndo Water Quality Control Division Biornortitoring_Gtudance Ductunent. dated hdy 1, 1993, where the receiving water is classified aquatic life, class 2 wiUtoat ell of the appropriate aquatic life numeric standards, acute WET testing is required, regardless ojdilution. Since the receiving waters far outfalls 012, 013, 014, 016, and 017 are classified as Class 2 Aquatic Life use, but without ell of t/te appropriate aquatic life numeric standards, the Division fins determined that acute WET testing is applicable jot these outfalls (also see jollowing paragraph). Since segment 12 is classified this way, these five outfalls are subject m acute LVET resting requirentems. 3) Acute WET Limuations - Ou~lls 012. 013. 014. Ol fi, and 017: The Division lies found that discharges ojpit pumpage, spoils spring water and similar sources front cool mines at similar sires /rave exhibited ejfluent tonicity. Also, toxicity failures have previously occurred jot some of the discharges a this jnciliry. On rIris basis, the Division believes there is reasonable potential for the discharges from outfalls 012. 013, 014, 016, and 017 to interfere with attainment of applicable water qunhn~ classifications or Stnndnrds. Because of tIris, the acute toxicity limit lies been incorporated into rite permit and becomes efjeuive immediately. The pennittee is reyuired m conduct routine morumring, the results of which ore to be reponed as at LCS«. !f the LCso s 100% efflueru, the penrtittee a required m conduct the uutantntic compliatce schedule us Identified in Part LA.4.c. of the pennu. •