AWWA WQTC71410

This powerpoint presentation begins by providing a brief overview of distribution system (DS) contamination through intrusion. The primary study objective was to estimate the public health risk associated with negative pressure events in a full-scale DS. Specific study objectives included: developing a transient model for evaluating pressures during downsurge events based on field measurements; estimating potential intrusion volumes considering two pathways, leakage orifices and submerged air vacuum valves (AVV); and, approximating concentration of contaminants at consumption nodes. Transient analysis with commercial software is presented, along with the impact of reduced wave speed on simulated pressure profiles, the impact of reduced wave speed on the extent of negative pressure zone, estimation of intrusion volumes, and estimation of theoretical intrusion volumes through leakage orifices using recorded pressures. Detailed conclusions are provided for wave speeds and for theoretical vs modeled intrusion volumes. Includes figures.