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California Regional Water Quality Control Board <br /> -A <br /> Central Valley Region <br /> x <br /> Karl E. Longley, ScD, P.E., Chair <br /> Arnold <br /> Linda S.Adams 11020 Sun Center Drive#200, Rancho Cordova, California 95670-6114 <br /> Schwarzenegger <br /> Secretary for <br /> Phone(916)464-3291 •FAX(916)464-4645 Governor <br /> Environmental http://www.waterboards.ca.gov/cer t' I /II L <br /> Protection ►�Jr� <br /> 21 January 2010 2 6 1010 <br /> ENVR30NN;ENT iaEAL TH <br /> �=Ei�1�tiTl'�ERtrl�'E <br /> Harold Rohrbach <br /> Woodbridge Sanitary District <br /> 19720 Benedict Drive <br /> Woodbridge, CA 95828 <br /> REQUEST FOR TECHNICAL REPORT, WOODBRIDGE SANITARY DISTRICT, SAN <br /> JOAQUIN COUNTY <br /> Central Valley Water Board staff has reviewed your 10 August 2009 letter regarding the <br /> recently revised flood insurance rate map (FIRM) for San Joaquin County. We understand <br /> that the revised FIRM map, which became effective on 16 October 2009, indicates that the <br /> Woodbridge Sanitary District Wastewater Treatment Facility is now located within the 100-year <br /> floodplain. Based on the revised FIRM map, it appears that the wastewater treatment facility <br /> (WWTF) would be subject to flooding depths of one to three feet. <br /> The treatment and disposal of wastewater at the Woodbridge Sanitary District Wastewater <br /> Treatment Facility is regulated by Waste Discharge Requirements Order 93-213. Discharge <br /> Specification B.5 of Order 93-213 states, "The treatment facilities shall be designed, <br /> constructed, operated, and maintained to prevent inundation or washout due to floods with a <br /> 100-year return frequency." Therefore, based on the revised FIRM map, the WWTF no longer <br /> complies with Discharge Specification B.5 of Order 93-213. <br /> Board staff understands that the District may need a substantial amount of time to implement <br /> a remedy to this situation. By 30 April 20310, please submit a Flood Evaluation, Report, <br /> prepared by a California Registered Engineer. The report needs to evaluate all components of <br /> the WWTF (head works, imhoff tanks, aeration ponds, evaporation ponds, etc.) for potential <br /> inundation or washout. The report should describe whether each component of the WWTF is <br /> protected from inundation or washout. For each component of the WWTF that is identified as <br /> not having adequate flood protection, the report should state the depth of flooding expected, <br /> and list potential short and long term solutions to prevent inundation or washout during the <br /> 100-year flood event. The report must also include a proposed time schedule with major <br /> milestones for completing the improvement project. <br /> Upon receipt of the report, Board staff will review the proposed schedule and evaluate the <br /> appropriate process to allow Woodbridge Sanitary District time to implement necessary <br /> improvements to the WWTF and come into compliance with Order 93-213. <br /> California Environmental Protection Agency <br /> c3Recycled Paper <br />