Laserfiche WebLink
Response to Written Comments 11- 24 April 2007 <br /> City of Tracy WWTP <br /> San Joaquin County <br /> water quality objective. Water quality-based effluent limitations for DO have <br /> been included in the proposed Order in accordance with federal regulations. <br /> CITY OF TRACY - NPDES COMMENT #17: PROVISION IV.A.1.1. ELECTRICAL <br /> CONDUCTIVITY. The City disagrees with the proposed effluent limitations for electrical <br /> conductivity because the final limits will likely become effective during the time while the <br /> Executive Officer must act, and then antibacksliding issues will arise. The City also <br /> contends that the options set forth in Enclosure 1 are problematic because these <br /> options require that reverse osmosis treatment will immediately or eventually be <br /> implemented. Given the large cost and environmental impact of reverse osmosis and <br /> brine disposal and the miniscule benefit given Tracy's contribution of salt to the Delta, <br /> none of the options proposed are supported by the City. <br /> RESPONSE: The Staff Report provides a detailed analysis of the compliance <br /> and permitting issues with respect to salinity. The Regional Water Board has <br /> several options to consider. <br /> CITY OF TRACY - NPDES COMMENT #18: Section IV.A.2.a, 3.a., 4.a., and 5.a., <br /> Tables 5-8. Mass and Daily Limits for Ammonia, Nitrate and Nitrite. The City <br /> contends that new monthly, daily, and mass effluent limitations for ammonia, nitrate, <br /> and/or nitrite are unwarranted. The City, without a requirement to do so, has begun <br /> constructing nitrification/denitrification facilities that will address these constituents and <br /> should be operational by the time this Permit becomes effective (e.g., 50 days after <br /> permit adoption). The City contends that there is not reasonable potential currently for <br /> nitrate and objects to the imposition of daily limits for ammonia and mass limits for <br /> ammonia, nitrate and/or nitrite. <br /> Request: Remove nitrate limits as there is no reasonable potential; remove the mass <br /> and daily limits for ammonia and nitrite as unjustified and unnecessary. <br /> RESPONSE: Untreated domestic wastewater contains ammonia. Nitrification is <br /> a biological process that converts ammonia to nitrite and nitrite to nitrate. <br /> Denitrification is a process that converts nitrate to nitrite or nitric oxide and then <br /> to nitrous oxide or nitrogen gas, which is then released to the atmosphere. <br /> Inadequate or incomplete denitrification may result in the discharge of nitrate <br /> and/or nitrite to the receiving stream. Therefore, the conversion of ammonia to <br /> nitrites and the conversion of nitrites to nitrates present a reasonable potential for <br /> the discharge to cause or contribute to an in-stream excursion above the Primary <br /> MCLs for nitrite and nitrate. <br /> Title 40 CFR 122.45 (d) requires average weekly and average monthly discharge <br /> limitations for publicly owned treatment works (POTWs) unless impracticable. <br /> However, for toxic pollutants and pollutant parameters in water quality permitting, <br /> Regional Water Quality Control Board, Central Valley Region <br /> Board Meeting— 3/4 May 2007 <br /> Item#17 <br />