AWWA WQTC65807

More utilities are using chloramines in place of free chlorine because of their greater stability for better compliance with both the Total Coliform Rule and more stringent requirements of the Disinfectants/Disinfection Byproducts Rule. New information about disinfectant-induced changes in oxidation reduction potential (ORP), lead chemistry, scale formation and interactions with natural organic matter have contributed to a greater understanding of the factors influencing increased corrosion and metals release associated with a change in disinfectant. As such, AwwaRF funded this project (#3107) to build upon the water industry's limited understanding of this effect. This project includes laboratory studies and a field sampling program. Identical pipe-loop setups and components testing procedures are being conducted at the HDR Applied Research and Technology Center (ARTC) in Bellevue, Washington and the District of Columbia Water and Sewer Authority (DCWASA) testing facility in Washington, DC. This paper provides a brief description of the setups, operations, preliminary data, and discussion of preliminary results. In general, preliminary results indicate the presence of chlorine tends to suppress lead release from old lead pipe but this effect appears to be less prominent for newly exposed lead-bearing materials. At the same time, copper release appears to be accelerated in the presence of chlorine. Both these effects are affected by water quality parameters, scales present on the surface and overall exposure history of corroding surfaces. Results from this study will be of interest to utilities that are considering converting from free chlorine to chloramines, and/or utilities concerned with maintaining simultaneous compliance with the Lead and Copper Rule and the Stage 2 D/DBPR. Includes 24 references, tables, figures.