ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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INFORMATION SHEET ORDER NO.R5-2004-0028 7 INFORMATION SHEET ORDER NO.R5-2004-0028 8 CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS WASTEWATER QUALITY CONTROL FACILITY WASTEWATER QUALITY CONTROL FACILITY SAN JOAQUIN COUNTY SAN JOAQUIN COUNTY b. The degradation after effective source control,treatment,and control is limited to waste 6 Thermal Limitations constituents typically encountered in municipal wastewater as specified in the groundwater limitations in this Order; The State Water Resources Control Board(State Board)Water Quality Control Plan for Control of c. The Discharger minimizes the degradation by fully implementing,regularly maintaining,and Temperatures in Coastal and Interstate Waters and Enclosed Bays and Estuaries of California(the optimally operating best practicable control technology(BPCT)measures;and Thermal Plan)is applicable to this discharge. The Thermal Plan requires that such a discharge: d. The degradation does not result in water quality less than that prescribed in the Basin Plan,e.g., (a) shall not exceed the receiving water temperature by more than 20°F; does not exceed water quality objectives. (b) shall not create a zone,defined by water temperatures of more than 1°F above natural Monitoring of the groundwater must be conducted to determine if the discharge has caused an increase receiving water temperature which exceeds 25%of the cross sectional area of the River in constituent concentrations,when compared to background. The monitoring must,at a minimum, at any point;and, require a complete assessment of groundwater impacts including an assessment of all wastewater- (c) shall not cause a temperature rise greater than 4°F above the natural temperature of the related constituents which may have migrated to groundwater,the vertical and lateral extent of any receiving waters at any time or place. degradation,and an analysis of whether additional or different methods of treatment or control of the discharge are necessary to provide best practicable treatment or control to comply with Resolution 68- For the purposes of compliance with the Thermal Plan,the Discharger is considered to be an existing 16. Economic analysis is only one of many factors considered in determining best practicable discharger of elevated temperature waste. Monitoring by the Discharger indicates that the 20 degree°F treatment. If monitoring indicates that the discharge has incrementally increased constituent limitation of Objective 5.A.(1)a of the Thermal Plan is occasionally exceeded in winter months when concentrations in groundwater above background,this permit may be reopened and modified. Until the receiving water is at its lowest temperatures. Modeling conducted by RMA,subject to the groundwater monitoring is sufficient,this Order contains Groundwater Limitations that allow limitations discussed below,indicates that the current and the expanded flows with continuous groundwater quality to be degraded for certain constituents when compared to background discharge exceed both the 1 degree and 4 degree requirements of Objectives 5.A.(1)b and 5.A.(1)c of groundwater quality,but not to exceed water quality objectives or standards. If groundwater quality is the Thermal Plan. The modeling also demonstrates that a timed discharge,that is,discharging only on shown to have been degraded by the wastewater treatment processes or the discharge,the incremental the outgoing tide,for the increased flow exceeds only the 4 degree requirement,but not the 1 degree change in pollutant concentration(when compared with background)may not be increased. This requirement. The Discharger has requested an exception to the 4 degree requirement of Objective Order may also be reopened and specific numeric limitations established. 5.A.(I)c of the Thermal Plan which requires that the discharge shall not cause a surface water The discharge authorized herein and the treatment and storage facilities associated with the discharge temperature rise greater than 4°F above the natural temperature of the receiving waters at any time or of treated municipal wastewater,except for discharges of residual sludge and solid waste,are exempt place and has also requested a one month averaging period to meet the 20 degree limit of Objective from the requirements of Title 27,CCR,Section 20005 et seq.(hereafter Title 27). The exemption, 5.A.(I)a. An exception cannot be authorized at this time due to a number of factors. First,the pursuant to Title 27,CCR,Section 20090(a),is based on the following: accuracy of the temperature model results which are the basis for the receiving water limitation violations are questionable due to a lack of site data to calibrate and validate the model,the lack of a. The waste consists primarily of domestic sewage and treated effluent; accounting for atmospheric heat gains and loss from the proposed holding pond and the river,the lack of accounting for tidal cycles and recirculation from the limited model run time,and the lack of b. The waste discharge requirements are consistent with water quality objectives;and accounting for the Brown Sand,Inc.discharge adjacent to the City's discharge.Second,the Discharger has not conducted regular monitoring of temperature at the outfall as required in its previous permit, c. The treatment and storage facilities described herein are associated with a municipal and the available information is based on a limited data set which correlates the temperature at the wastewater treatment plant. plant site and at the outfall. Third,the Discharger has not provided adequate evidence that a 30-day averaging period for Effluent Limitation B.11.will not cause adverse impacts to aquatic life. Finally, This Order requires the Discharger to prepare technical and monitoring reports as authorized by the Discharger does not currently have the capability to implement a timed discharge on out-going California Water Code(CWC)Section 13267. This Order also requires that the Discharger conduct tides. groundwater monitoring and includes a regular schedule of groundwater monitoring in the attached Monitoring and Reporting Program. The groundwater monitoring reports are necessary to evaluate Effluent Limitations and Receiving Water Limitations are included to require compliance with the impacts to waters of the State to assure protection of beneficial uses and compliance with Regional Thermal Plan. If adequate information is developed to support exceptions to the Thermal Plan,this Board plans and policies,including Resolution 68-16,and to assure compliance with this Order. Order may be reopened to modify limitations for Thermal Plan compliance.