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PART I Page 6 Permit No. CO-0044776 A. DEFINITION OF EFFLUENT LL~[ITATIONS • 6. Whole Effluent Tonicity Testfn~Requirements (Acute) - Outfall 002 (conlinuedl The permittee shall conduct an acute 48-hour WET test using Ceriodaphnia sp., and an acute 96-hour WE'f test using fathead minnows. Acute tests will be replacement static tests of a single effluent grab sample. The petmittee shall conduct each acute WET test in general accordance with methods described in Methods for Measuring the Acute Toxicity of EfFluents and Receiving Waters to Freshwater and Marine Organisms, EPA/600/4-90/027 or the most current edition, except as modified by the most current Division guidance document entitled Guidelines for Conducting Whole Effluent Toxici , Tests. b. Failure of Tes[ and Division Notification An acute WET test is failed whenever the LCso, which represents an estimate of the effluent concentration which is lethal to 50% of the test organisms in the time period prescribed by the test, is found to b<: less than or equal to 100% effluent. The permittee must provide written notification of the failure of a WET test to the Division, along with a statement as to whether the Preliminary Toxicity Incident ("PTI")/Toxicity ]dentific;ttion Evaluation ("TIE") investigation or accelerated testing is being performed (see next section). Notification must be received by the Division within 14 calendar days of the demonstration of acute WET in the routine required test. "Demonstration" for the purposes of Parts i,A.4.b., c., d. and f. means no later than the la:ct day of the laboratory test. c. Automatic Comp1jance Schedule Ueon Failure of Test If a rou[ipe acute WET test is failed, the following automatic compliance schedule shall apply. As pan of this. the pennittee shall either: i. proceed to conduct the PTIITIE investigation as described in Part I.A.4.d., or ii. conduct accelerated testing using the single species found to be more sensitive. It accelerated testing fs 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 pattern of toxicity has been demonstrated or, 2) two consecutive tests pass or three of five tests pass, in which case no pattern of toxicity has been found. If no pattern of toxicity is found the toxicity episode is considered to be ended and routine testing is to resume. If a pattern of toxicity is found, aPTI/TIE investigation is to be performed. If a pattern 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 The results of the PTI/TIE investip~ion are to be received by the Division within 120 days of the ~mnnctratinn of acme WFT in the rmitine feet ac deemed above or ff accelerated testinE is cerformed the date the pgttero of toxicity,is demonstrated A status report is to be provided to the Division at the 30 4S and 90 day ((Dints of the PTI/TIE investippHon The Division may extend the time frame for investigation where reasonable justification exists. A request for an extension must be made in writing and received prior [o the l20 day deadline. Such request must include a justification and suppotting data for such an ex[ettsion. The permittee may use the time for investigation to conduct a PTI or move directly into the TIE. A PTI con>is of a brief search for possible sources of WET, which might reveal causes of such toxicity and appropriate corrective actions more simply and cost effectively than a formal TIE. IF the PTl allows resolution of the W]- incident, the TIE need not necessarily be conducted. if, however, WET is not identified or resolved during the PTI, the TIE must be conducted within the allowed L20 day time frame. .JU~ 2 ~ ~'~~'-. Amendment No. I Issued Effective AU'' U ~~_