AWWA DSS69197

This powerpoint presentation begins by providing a brief overview of Dallas Water Utilities and a case study involving colored water complaints. The study design included monitoring 16 distribution system locations for a period of 12 months, and monitoring of parameters that included: pH; disinfection residual; assimilable organic carbon (AOC); biological growth indicators - HPCs; nitrification indicators - Nitrite, Nitrate, AOB; and, corrosion indicators - iron, turbidity. Elements contributing to the cause of colored water were identified as the following: water leaving the treatment plants was biologically unstable; biological re-growth, nitrification and lowering of pH in the distribution system; and, the leaching of pipe scale resulted in red water at customer taps. A pilot study of pipe wall/ water interactions is presented, along with colored water management strategies for treatment plants including enhanced coagulation, biological filtration, and chlorine/ammonia ratio of 5:1. Recommended colored water treatment strategies for the distribution system included periodic flushing, booster chlorination, and corrosion inhibitor addition. Includes tables, figures.