Chloramine Conversion Projects - Purissima Hills Water District and Skyline County Water District, CA
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In February 2004, the San Francisco Public Utilities Commission (SFPUC), who supplies water to most water districts on the San Francisco Peninsula, changed the method of secondary disinfection from chlorination to chloramination. Chloramine is regarded as a better disinfectant than chorine alone because it lasts longer in water to more effectively inactivate pathogens such as bacteria and viruses. Compared to chlorine, chloramine produces lower levels of trihalomethanes, haloacetic acids, and suspected carcinogens that form when chlorine mixes with natural organic substances in water.
Although superior in many ways, this disinfectant has a few drawbacks, including the possible nitrification of water stored for extended periods of time. Pakpour Consulting Group evaluated each districts distribution and storage systems using WaterCAD® models and physical data to pinpoint locations where nitrification may occur. Pakpour Consulting Group also assisted each district in developing an extensive monitoring program to measure levels of disinfectant in their distribution system.
Operational recommendations include increasing reservoir drawdown where hydraulically possibly to increase turnover, as well as procedures for chemical additions such as breakpoint chlorination. Pakpour Consulting Group also prepared a monitoring program, a flushing program, and a nitrification response program for each water district.
