AWWA WQTC69236

The objective of this research project was to evaluate operational strategies for reducing water residence time in distribution networks to favor adequate concentrations of residual chlorine while minimizing disinfection byproducts (DBPs) in problematic sectors, such as low consumption areas and areas with a high number of dead-ends, as illustrated in a case study of Quebec City, Canada. The paper focuses on the approach for determination of water travel patterns in the distribution system, in variable hydraulic conditions. The case study is the main distribution system of Quebec City, supplied by the St. Charles River at Loretteville Drinking Water Plant (DWP). It is a widespread network that provides water to about 40% of the city's population (i.e. about 230,000 people). This distribution system has possible unwanted and unknown interconnections with neighboring networks. Once the hydraulic model was completed, preliminary water age and chlorine residuals were calculated using EPANET. Two sampling campaigns were designed, in different sectors and periods of time, using tracers to monitor water age at different locations. Results from these campaigns will be used to calibrate the hydraulic model to evaluate hydraulic scenarios to reduce water age, enhance residual chlorine concentration and, thus, improve water quality. Includes 8 references, figures.