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PART I Page 22 of 56 C00032115 A chronic WET test is considered to have failed one of the two statistical endpoints when either the NOEC or the IC25 are at any effluent concentration less than the IWC. Simultaneous failure of both the NOEC and IC25 for both sub -lethal endpoints, when tests are performed on identical split samples, constitutes only a single violation of the Daily Maximum Effluent Limitation for Chronic WET specified in Part I, SA -2 of this permit. The IWC for this permit has been determined to be 100% effluent. In the event of a permit violation, or during a report only period when both the NOEC and the IC25 are at any effluent concentration less than the IWC, or when two consecutive reporting periods have resulted in failure of one of the two statistical endpoints (regardless of which statistical endpoints are failed), the permittee must provide written notification to the Division. Such notification should explain whether it was a violation or two consecutive failures of a single endpoint, and must indicate whether accelerated testing or a Toxicity Identification Evaluation or Toxicity Reduction Evaluation (TIE or TRE) is being performed, unless otherwise exempted, in writing, by the Division. Notification must be received by the Division within 14 calendar days of the permittee receiving notice of the WET testing results. c. Automatic Compliance Response The permittee is responsible for implementing the automatic compliance response provisions of this permit when one of the following occurs: 1. there is a violation of the permit limit (both the NOEC and the IC25 endpoints are less than the applicable IWC) 2. during a report only period when both the NOEC and the IC25 are at any effluent concentration less than the IWC 3. two consecutive monitoring periods have resulted in failure of one of the two statistical endpoints (either the IC25 or the NOEC), including during a report -only period. This determination is made independently for each test species. 4. the permittee is otherwise informed by the Division that a compliance response is necessary When one of the above listed events occurs, the following automatic compliance response shall apply. The permittee shall either: 1. conduct accelerated testing using the single species found to be more sensitive 2. conduct a Toxicity Identification Evaluation (TIE) or a Toxicity Reduction Evaluation (TRE) investigation as described below. i. Accelerated Testing If accelerated testing is being performed, testing will be at least once every two weeks for up to five tests, running only one test at a time, using only the IC25 statistical endpoint to determine if the test passed or failed at the appropriate IWC. Accelerated testing shall continue 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. Note that the same dilution series should be used in the accelerated testing as was used in the initial test(s) that result in the accelerated testing requirement. If accelerated testing is required due to failure of one statistical endpoint in two consecutive monitoring periods, and in both of those failures it was the NOEC endpoint that was failed, then the NOEC shall be the only statistical endpoint used to determined whether the accelerated testing passed or failed at the appropriate IWC. Note that the same dilution series should be used in the accelerated testing as was used in the initial test(s) that result in the accelerated testing requirement. 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, a TIE/TRE 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. The permittee shall