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Mr. Robert Meleg - 6 - 22 July 2003 Public Works Director Regional Board plans and policies encourage recycling of treated domestic wastewater whenever feasible. The RWD indicates that the City will investigate plans for recycling over a several year period. The tentative draft WDRs will require the City to submit a detailed plan of how it intends to proceed with this investigation and implement recycling where feasible. In summary, groundwater in the WWTF vicinity is being adversely impacted by the WWTF and its discharge to disposal ponds. The effluent quality for organics and nutrients proposed in the RWD are neither protective of groundwater nor reflective of BPTC. Tentative WDRs for Regional Board consideration would, if adopted,require the City to implement mitigation measures to reduce the discharge's impact on underlying groundwater to a level that, at a minimum, precludes a condition of pollution. Mitigation measures would include: (1) implementing treatment technology for pathogen removal; (2) implementing water recycling; (2) sealing all treatment ponds (including existing treatment ponds) and sludge handling facilities to permeabilities reflective of BPTC, and (3) establishing, at a minimum, the following effluent limitations for discharge to percolation ponds: BOD (10 mg/L), TSS (10 mg/L), total nitrogen (8 mg/L), TCO (2.2 MPN/100 mL), and EC of 500 µmhos/cm over source water EC. This level of treatment is higher than that indicated in Regional Board letter of 1 May 2003, which identified tentative effluent limits for BOD5 and TSS of 20 mg/L each. The lower effluent BOD5 and TSS limitations are necessary, in part, because recently submitted data shows groundwate>-is already significantly degraded by oxygen-demanding substances. The tentative WDRs will also authorize a phased flow increase from what is currently required by the CAO to a future domestic flow of 2.6 mgd and a Cannery flow of 2.7 mgd as the City upgrades its treatment capacity to levels established by the Regional Board. If have questions regarding the matter above, please contact Alexis R. Phillips-Dowell at (559) 445-5500. 0,bVUt,_-0_ Ie,y� _ - ANNE KJPPS Senior Engineer RCE NO. 49278 cc: Mike Huggins, San Joaquin County Department of Health Services, Stockt� Denise Wood, Stanislaus County Environmental Resources Department,Modesto Mike Anderson, Nolte Associates, Inc., Sacramento V:\Municipal\Staft\PHBddA\RWD\rwd Riverbank complete.doe N15/STANISLAUS/RIVERBANK,CITY OF/RIVERBANK W WTP/5C500106002