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PART I <br />Page No. 14 <br />Permit No.: CO-0000906 <br />• iv. Despite the circumstances described in paragraphs (i) and (iii) above, the source and/or cause of toxicity could not be <br />located or resolved. <br />If deemed appropriate by the Division, the permit or the compliance schedule may be modified to revise the ongoing <br />monitoring and toxicity investigation requirements to avoid an unproductive expenditure of the permittee's resources, <br />provided that the underlying obligation to eliminate any continuing exceedance of the toxicity limit shall remain. <br />f. Spontaneous Disappearance <br />if toxicity spontaneously disappears at any time after a test failure, the permittee shall notify the Division in writing <br />within 14 days of a demonstration of disappearance of the toxicity. The Division may require the pennittee to develop <br />and submit additional information, which may include, but is not limited to, the results of additional testing. If no pattern <br />of toxicity is identified or recurring toxicity is not identified, the toxicity incident response is considered closed and <br />normal WET testing shall resume. <br />g. Toxicity Reopener <br />This permit may be reopened and modified (following proper administrative procedures) to include new compliance <br />dates, additional or modified numerical permit limitations, a new or different compliance schedule, a change in the whole <br />effluent toxicity testing protocol, or any other conditions related to the control of toxicants if one or more of the following <br />events occur: <br />i. Toxicity has been demonstrated in the effluent and the permit does not contain a toxicity limitation. <br />ii. The PTI/TIE results indicate that the identified toxicant(s) represent pollutant(s) that may be controlled with specific <br />• numerical limits and the permit issuing authority agrees that the control of such toxicants through numerical limits is <br />the most appropriate course of action. <br />iii. The PTI/TIE reveals other unique conditions or characteristics, which, in the opinion of the permit issuing authority, <br />justify the incorporation of unanticipated special conditions in the permit. <br />5. Acute WET Testing-Outfall(s)• 009A 009B and 009C <br />Testing and Reporting Requirements <br />Tests shall be done at the frequency listed in Part I.B.I . Test results shall be reported along with the Discharge <br />Monitoring Report (DMR) submitted for the end of the reporting period when the sample was taken. (i.e., WET testing <br />results for the calendar quarter ending March 31 shall be reported with the DMR due April 28, etc.) The results shall be <br />submitted on the Acute Toxicity Test report form, available from the Division. Copies of these reports are to be <br />submitted to the Division along with the DMR. <br />The permittee shall conduct each acute WET test in general accordance with methods described in Methods for <br />Measuring the Acute Toxici of Effluents and Receiving, Waters to Freshwater and Marine Or anisrns EPA/600/4- <br />90/027 or its most current edition, except as modified by the most current Division guidance document entitled <br />Guidelines for Conducting Whole Effluent Toxicity Tests. The permittee shall conduct an acute 48-hour WET test using <br />Ceriodaphnia sp., and an acute 96-hour WET test using fathead minnows. Acute tests will be replacement static tests of a <br />single effluent grab sample. <br />b. Failure of Test and Division Notification <br />An acute WET test is failed whenever the LC5o, which represents an estimate of the effluent concentration which is lethal <br />to 50% of the test organisms in the time period prescribed by the test, is found to be less than or equal to 100% effluent. <br />• The pern ittee must provide written notification of the failure of a WET test to the Division, along with a statement as to <br />whether the Preliminary Toxicity Incident (PTI)/Toxicity Identification Evaluation (TIE) investigation or accelerated <br />testing is being performed. Notification must be received by the Division within 14 calendar days of the <br />demonstration of acute WET in the routine required test. Demonstration for the purposes of Parts I.A.5.b., c., d. and <br />(f) means no later than the last day of the laboratory test.