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PART i <br />Page !0 <br />Permit No. CO-0038776 <br />B. MOMTORING REQUIItEMENTS <br />3. Acute WET Testing - Outfalls 002. 004. 011 and 013 (continued) <br />The permittee shall conduct an acute 48-hour WET test using Ceriodaphnia sp., and an acute 96-hour WET test using <br />fathead minnows. Acute tests will be replacement static tests of a single effluent grab sample. The permittee shall <br />conduct each acute WET test in general accordance with methods described in Methods for Measuring the Acute <br />Toziciry of Effluents and Receiving Waters to Freshwater and Marine Organisms, EPA/600/4-90/027 or the most <br />curten[ edition, except as modified by the most current Division guidance document entitled Guidelines for Conducting <br />Whole Effluent Toziciry Tests. <br />(b) Failure of Test and Division Notification <br />An acute WET test is failed whenever the LCso, which represents an estimate of the effluent concentration which is <br />lethal [0 50% of the test organisms in the time period prescribed by the test, is found to be less than or equal to 100% <br />effluent. The permittee must provide written notification of the failure of a WET test to the Division, along with a <br />statement as [o whether the Preliminary Toxicity Incident ("PTi")/Toxicity Identification Evaluation ("TIE") <br />investigation or accelerated testing is being performed (see nett section). Notification must be received by the <br />Division within 14 calendar days of the demonstration of acute WET in [he routine required test. <br />"Demonstration" for the purposes of Parts [.6.4(b),(c),(d) and (f) means no later than the last day of the laboratory <br />test. <br />(c) Automatic Compliance Schedule Uoon Failure of Test <br />• If a routine acute WET test is failed, the following automatic compliance schedule shall apply. As pazt of [his [he <br />permittee shall either: <br />(i) proceed to conduct the PTI/TIE investigation as described in Par[ I.B.4.(d), or <br />(ii) conduct accelerated testing using [he single species found to be more sensitive. <br />If accelerated testing is being performed, the permittee shag provide written notification of the results within l4 <br />calendar days of completion of the "Pattern of Toxicity"/"No Toxicity" demonstration. Testing will be at least <br />once every two weeks for up to five tests until l) two consecutive tests fail or three of five tests fail, in which case a <br />pattern of toziciry has been demonstrated or, 2) two consecutive tests pass or three of five tests pass, in which case no <br />pattern of toxicity has been Found. If no pattern of toxicity is found the toziciry episode is considered to be ended and <br />routine testing is to resume. If a pattern of toxicity is found, aPTI/TiE investigation is to be performed. If a pattern <br />of toxicity is not demonstrated but a significant level of erratic toxicity is found, the Division may require an increased <br />frequency of routine monitoring or some other modified approach. <br />(d) PTI/TIE <br />The results of the PTI/TIE investigation are [o be received by the Division within 120 days of the demonstration <br />of acute WET in the routine [es[ as defined above or if accelerated testing is performed the date the pgttern of <br />tonicity is demonstrated A status report is to be provided to the Division at the 30 60 and 90 day points oP the <br />PTI/TIE investiEation. The Division may extend the time frame for investigation where reasonable justification <br />exists. A request for an extension must be made in writing and received prior to the I20 day deadline. Such request <br />must include a justification and supporting data for such an extension. <br />The permittee may use the time for investigation [o conduct a PTI or move directly into the TIE. A PTI consists of a <br />• brief search for possible sources of WET, which mtgh[ reveal causes of such toxicity and appropriate corrective <br />actions more simply and cost effectively than a formal TIE. If the PTI allows resolution of the WET incident, [he TfE <br />need not necessarily be conducted. If, however, WET is not identified or resolved during the PTI, the TIE must be <br />conducted within the allowed 120 day time frame. <br />See Part I.C. for Definitions. Amendment No. 2 Issued FEB t 9, t 997 Effective APR O 7 . 1997 <br />