Res 2005-105 - Laserfiche WebLink

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City of San Marcos TPDES Permit No. WQOOI0273002 4. Persistent Toxicity The requirements of this Part apply only when a test demonstrates a significant effect at the critical dilution. A significant effect is defined as a statistically significant difference, at the 95% confidence level, between a specified endpoint (survival, growth, or reproduction) of the test organism in a specified effiuent dilution when compared to 1he specified endpoint of the test organism in the control. Significant lethality is defined as a statistically significant difference in surviyal at the critical dilution when compared to the survival of the test organism in the control. Significant sub lethality is defined as a statistically significant difference in growth/reproduction at the critical dilution when compared to the growth/reproduction of the test organism in the control. a. The permittee shall conduct a total of 2 additional tests (retests) for any species that demonstrates a significant effect (lethal or sublethal) at the critical dilution. The two retests shall be conducted monthly during the next two consecutive months. The permittee shall not substitute either of the two retests in lieu of routine toxicity testing. All reports shall be submitted within 20 days oftest completion. Test completion is defined as the last day of the test. The retests shall also be reported on the DMRs as specified in Part 3.d. b. If the retests are performed due to a demonstration of significant lethality, and one or both of the two retests specified in item 4.a. demonstrates significant lethality, the permittee shall initiate the TRE requirements as specified in Part 5. The provisions of item 4.a. are suspended upon completion of the two retests and submittal of the TRE Action Plan and Schedule defined in Part 5. If neither test demonstrates significant lethality and the permittee is testing under the reduced testing frequency provision of Part I.e., the permittee shall return to a quarterly testing frequency for that species. c. Ifthe two retests are performed due to a demonstration of significant sublethality, and one or both ofthe two retests specified in item 4.a. demonstrates significant lethality, the permittee shall again perform two retests as stipulated in item 4.a. d. If the two retests are performed due to a demonstration of significant sublethality, and both retests pass, the permittee shall continue testing at the quarterly frequency until such time that the permittee can invoke the reduced testing frequency provision specified in Part I.e. e. Regardless of whether retesting for lethal or sublethal effects, or a combination of the two, no more than one retest per month is required for a species. 5. Toxicity Reduction Evaluation a. Within 45 days of the last test day of the retest that demonstrates significant lethality, the permittee shall submit a General Outline for initiating a TRE. The outline shan include, but not be limited to, a description of project personnel, a schedule for obtaining consultants (if needed), a discussion of influent and/or effluent data available for review, a sampling and analytical schedule, and a proposed TRE initiation date. b. Within 90 days of the last test day of the retest that demonstrates significant lethality, the permittee shan submit a TRE Action Plan and Schedule for conducting a TRE. The plan shan specify the approach and methodology to be used in performing the TRE. A Toxicity Reduction Evaluation is a step-wise inyestigation combining toxicity testing with physical and chemical analysis to determine actions necessary to eliminate or reduce effluent toxicity to a level not effecting significant lethality at the critical dilution. The TRE Action Plan shall lead to the successful elimination of significant lethal effects at the critical dilution for both test species defined in item l.b. As a minimum, the TRE Action Plan shall include the following: 1) Specific Activities - The TRE Action Plan shall specify the approach the permittee intends to utilize in Page 29