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Messrs. Hill and Machado - 3 - 9 May 2003 The addition of a major industrial waste discharge to a discharge of essentially domestic sewage, or the addition of a new process or product by an industrial facility resulting in a change in the character of the waste. Staff has determined that an RWD is required for this project for the following reasons: • The MEGS project will add industrial waste to the domestic wastewater system. That addition requires an RWD submittal; • Discharge of MEGS wastewater will result in increased dissolved solids discharged to the City's system. The TDS concentration of the City's domestic wastewater effluent has increased since 1999 from 655 mg/L to 736 mg/L and the addition of more industrial wastewater will increase the TDS concentration further. Because the wastewater treatment plant does not reduce the concentrations of TDS, such increases will likely lead to groundwater degradation; • The 25 March 2003 technical report relies primarily on dilution to reduce the concentration of dissolved solids discharged to the City system. Because the City applies the treated wastewater to land, the total load of dissolved solids applied will increase with the addition of the industrial wastewater; and • The nitrate concentration of the combined flow is reported to be 264 mg/L. In the first quarter of 2003, four of the six groundwater monitoring wells contained nitrogen as nitrogen concentrations that exceeded the Maximum Contaminant Level (10 mg/L). The groundwater concentrations varied from 7.9 to 50 mg/L. Adding wastewater that contains such high concentrations of nitrogen is likely to worsen the groundwater quality at the facility. Based on the discussion presented above, staff believes the addition of the MEGS project wastewater to the City of Ripon's wastewater treatment system is a material change to the existing discharge and as such an RWD is required to describe how the wastewater will be treated and disposed of in a manner that is protective of groundwater quality. You may submit it at your convenience, but please note that it can take up to four months from receipt of a complete RWD to adoption of WDRs, and that a change in the wastewater quality discharged to the system will not be allowed until WDRs are adopted. Please call me at (916) 255-3116 if you have any questions regarding this request for a RWD. TIMOTHY R O'BRIEN Waste Discharge to Land Unit Lower San Joaquin River Watershed cc: Mike Huggins, San Joaquin County Environmental Health Department, Stockton Steven DeYoung, DeYoung Environmental Consulting, Walnut Creek Dave Jones, CH2MHILL, Sacramento Colin McCae, PB Power, Inc., San Francisco Susan Strachan, Strachan Consulting, Davis V 15an lord^ni Fonlf'SimpWnc^T1mJo:u�nm'.Riqn MW PlNbd .2 Yl:n'm pa