SITE INFORMATION AND CORRESPONDENCE 1980-1999

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WASTE DISCHARGE REQUIREMENTS ORDER NO. 5-00- -21- CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY When conducting chronic toxicity tests, the following will be the trigger level requirements: a. Accelerated monthly monitoring for six months after exceeding a single sample maximum value of 1 TUc(I). b. Return to routine monitoring if accelerated monitoring does not exceed the trigger level in item no. 2 is exceeded with six (6) consecutive months. c. Initiate approved TIE/TRE workplan if accelerated monitoring confirms consistent toxicity above trigger in item no. 2. d. Return to routine monitoring after appropriate elements of TRE workplan are implemented or toxicity drops below trigger level in item no. 2, or as directed by the Executive Officer. The Discharger shall develop a TRE workplan acceptable to the Executive Officer within six (6) months after adoption of this Order. The purpose of the TRE is to investigate the causes of, and to identify corrective control actions in response to effluent toxicity incidents. The objective of the TRE is to narrow the search for effective control measures for effluent toxicity. The TRE needs to be site specific but should follow EPA guidance and be conducted in a step-wise fashion. The following is a tiered approach in conducting the TRE: Tier I includes basic data collection, followed by Tier 2, which evaluates optimization of the treatment system operation, facility housekeeping, and the selection and use of in- plant process chemicals. If unsuccessful in reducing toxicity, Tier 3, a toxicity identification evaluation(TIE) should be initiated and all reasonable efforts using currently available TIE methodologies employed. Assuming successful identification or characterization of the toxicant(s), Tier 4 is to evaluate final effluent treatment options and Tier 5 is to evaluate within plant treatment options. Tier 6 consists of follow-up and confirmation once the toxicity control method has been selected and implemented. Many recommended TRE elements parallel source control,pollution prevention, and storm water control program best management practices (BMPs). To prevent duplication of efforts, evidence of complying with those requirements may be sufficient to comply with TRE requirements. By requiring the first steps of a TRE to be accelerated testing and review of the facility's TRE workplan, a TRE may be ended in its early stages. All reasonable steps shall be taken to reduce toxicity to the required level. A TUc equals 100 divided by the no observable effect level(NOEL). The NOEL is determined from IC,EC,or NOEC values. Monitoring and TRE requirements may be modified by the Executive Officer in response to the degree of toxicity detected in the effluent or in ambient waters related to the discharge.