SITE INFORMATION AND CORRESPONDENCE 1980-1999

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FACT SHEET, ATTACHMER C • -4- WASTE DISCHARGE REQUIREMENTS ORDER NO. 5-00- CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY wastewater, then the wastewater should be adequately oxidized, coagulated, filtered, and disinfected. The wastewater should be considered adequately disinfected if: 1) The chlorine disinfection process provides a CT (residual chlorine concentration times modal contact time) value of not less than 450 milligram-minutes per liter at all times, with a modal contact time of at least 90 minutes, based on peak dry weather design flow; and 2) The median concentration of total coliform bacteria measured in the disinfected effluent does not exceed an MPN of 2.2 per 100 ml utilizing the bacteriological results of the last seven days for which analyses have been completed and the number of total coliform bacteria does not exceed an MPN of 23 per 100 ml in more that one sample in any 30 day period. No single sample should exceed an MPN of 240 per 100 ml for total coliform bacteria. In accordance with the recommendations of the DHS, this permit contains a time schedule to require a higher level of treatment for disinfection. The Board has considered the factors specified in Water Code Section 13263, including considering the provisions of Water Code Section 13241, in adopting the coliform limitation in the proposed waste discharge requirements. In a letter from the City of Lodi (dated 24 February 1999) to the Regional Water Quality Control Board, the city provided a cost estimate of between $10 to $15 million dollars to design and construct the proposed disinfection. To date, there has been no elaboration or refinement of this rough estimate. Staff finds, that these requirements are necessary to protect the beneficial uses of Dredger Cut, Bishop Cut, and White Slough, including public health impacts of recreational uses and irrigation uses of the receiving waters. This Order provides interim limits for total coliform, which the Discharger is currently capable of meeting. Full compliance with the turbidity limitation and the 2.2 MPN/100 ml total coliform limitation is not required by this Order until 1 May 2004. Adequate time is provided for the Discharger to propose alternatives that are still protective of public health and irrigation uses but at a reduced cost. The permit may be reopened at such time as the Discharger proposes an alternative that is protective of public health and irrigation use. e) Ammonia Due to concerns discussed above over impacts of expanding the discharge on dissolved oxygen, the treatment plant flows have been held to a maximum of 7.0 mgd, whereas it was designed to treat up to 8.5 mgd of secondary-treated effluent. Actual flows have not exceeded 6 mgd. While operating at less than the design capacity, the plant has been effective at removing ammonia by nitrification. At this time there are no effluent limitations for ammonia. If flows increase such that the plant is no longer capable of removing ammonia, then ammonia may be discharged at a concentration that may cause or have the reasonable potential to cause, or contribute to toxicity in the receiving water. If