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CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION ORDER NO. WASTE DISCHARGE REQUIREMENTS FOR COUNTY OF SAN JOAQUIN COUNTY SERVICE AREA NO. 31 FLAG CITY WASTEWATER TREATMENT FACILITY SAN JOAQUIN COUNTY The California Regional Water Quality Control Board, Central Valley Region, (hereafter Board) R (� finds that: lul\\vl I 1. The San Joaquin County Department of Public Works (hereafter Discharger) submitted a Report of Waste Discharge, dated 7 July 1997, and additional information dated 6 May 1998, for their wastewater treatment and disposal facility. The property (Assessor's Parcel No. 055- T 320-09) is owned by the Discharger. 2. San Joaquin County Service Area(CSA)No. 31 is in Sections 13 and 14, T3N,RSE, MDB&M, with surface water drainage to Dredger Cut which is tributary to White Slough, as shown in Attachment A,which is attached hereto and part of the Order by reference. r 3. Flag City Wastewater Treatment Plant has been operating under a National Pollutant Discharge Elimination System (NPDES)permit(Order No. 92-060, Permit No. CA0082848)adopted by the Board on 27 March 1992. This permit prescribed requirements for the treatment and surface water discharge of treated effluent from a commercial development along the junction of Interstate 5 and State Route 12. Development has been slow,however, and influent flows comprise only a fraction of the plant's design flow of 0.16 million gallons per day (mgd). The Discharger has been operating the plant as a continuous flow extended aeration activated sludge facility,which is better for handling low hydraulic and organic loading conditions. 4. Although the permit regulates a discharge to Highline Canal, since plant startup in late 1995, disposal has been to an evaporation and percolation(EP) pond. This pond was originally intended to be used as an emergency pond, but because of the extremely light hydraulic and organic loading,the plant could not reliably produce effluent to meet permit limitations for a surface water discharge. With Discharger concurrence,Board staff have recommended that waste discharge requirements be adopted in place of the NPDES permit until such time that the land discharge capability is exhausted. The Discharger will apply to the Board for another NPDES permit at least six months before the time that surface water discharge arrangements are needed. An engineered report shall be submitted six (6) months from the date of adoption of this Order that provides the basis for timing of the permit application submittal. The report shall contain a pond capacity evaluation, an analysis demonstrating that all land discharge options will be exhausted, and a proposed flow rate that will trigger submittal of the NPDES permit application.