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PART I Page viii Permit No. CO-0043567 B. MONITORING REQUIREMENTS 4. Chronic WET Testine-Outfalls 001. 002 and 003 (continued) The permittee shall conduct each chronic WET test in general accordance with methods described Short Term Methods (or Estimetine the Chronic Toxicity of EfFluents and Receivine Waters to Freshwater Oreanisms, EPA/600/4-89/001 or the most current edition, except as modified by the most current Division guidance document entitled Guidelines for ~~ Conductive Whole Effluent Toxicity Tests. The pertnittee shall conduct such tests using Ceriodaphnia dubia and fathead mIMOWS. (b) Failure of Test and Division Notification A chronic WET lest is failed whenever there is a statistically significant difference in lethality between the control and any effluent concentration less than or equal to the instream waste concentration ('IWC"). The IWC for this permit has been determined to be 100°.b. The permittee must provide written notification of the failure of a WET test to the Division, along with a statement es to whether a Preliminary Toxicity Investigation ('PTl')/Toxicity Identification Evaluation ("TIE") or accelerated testing is being performed (see Parl 1.B.3.c)). Notification must be received by the Division within 21 calendar days of the demonstration of chronic N'ET in the routine required lest. 'Demonstration' for the purposes of Parts 1.B.4(b),(c),(d) and (f) means no later than the last day of the laboratory test. (c) Automatic Compliance Schedule Upon Failure of Test If a routine chronic WET test is failed, even though monitoring only is required, the following automatic compliance schedule shall apply. As part of this the permittee shall either: (i) proceed to conduct the PTI/T1E investigation as described in Part I.B.4.d, or (ii) conduct accelerated testing using the single species found to be mare sensitive. If accelerated testing is being performed, the permittee shall provide written notification of the results within 14 calendar days of completion of the "Pattern of Toxicity"/"No Toxicity" demonstration. Testing will be at least once every two weeks for up to five tests until; 1) two consecutive tests fail or three of five tests fail, in which case a pattem of toxicity has been demonstrated or 2) two consecutive tests pass or three of five tests pass, in which case no pattem of toxicity has been found. If no pattem of toxicity is found the toxicity episode is considered to be ended and routine testing is to resume. If a pastern of toxicity is found, aPTI/TIE investigation is to be performed. If a pattem of toxicity is not demonstrated but a significant level of erratic toxicity is found, the Division may require an increased frequency of routine monitoring or some other modified approach. (d) PTI/TIE pmnts of the Yl7/ tlr mvesheatton. the Urvtston may extend the hme frame for mvesugahon where reasonable justification exists. A request for an extension must be made in writing and received prior to the 120 day deadline. Such request must include a justification and supporting data for such an extension. The permittee may use the time for investigation to conduct a PTI or move directly into the TIE. A PTI consists of a beef search for possible sources of WET, which might reveal causes of such toxtcity and appropriate corrective actions more simply and cost effectively than a formal TIE. If the PTI allows resolwion of the WET incident, the TIE need nut necessarily be conducted. If, however, WET is not identified or resolved dunne the PTI, the TIE must be conducted within the allowed 120 day time frame. Any permittee that is required to conduct a PTl/TIE investigation shall do so to conformance with procedures identified in the following documents, or as subsequently updated: 1) Toxicity Identification Evaluation: Characterization of Chronically Toxic Effluents. Phase I, EPA/60016-9 1 /OOSF May 92, 2) Methods for Aquatic Toxicity IdeNificahon Evaluations Phase I Toxicity Characterization Procedures, EPA/600/6-91/003 Feb. 9l and 3) Methods (or Amuwc Toxicity Identification Evaluations. Phase II Tozicity Identification Procedures EPA/600/3-88/035 Feb. 1989. A fourth document in this' series is Methods for Aquatic Toxicny Identification Evaluations, Phase III Toxicity Confirmation Procedures, EPA/600/3-88/036 Feb. 1969. As indicated by the title, this procedure is intended to conlirm that the suspected toxicant is truly the toxicant. This investigaton is optional. Within 90 days of the determination of the toxicant or no later than 210 days aFter demonstration of toxicity, whichever is sooner, a control program is to be developed and reserved by the Division. The program shall set down a method ;md pnicedure for elimination o(the toxicuy to acceptable levels.