AWWA WQTC65947

Continuous monitoring of water pressure, using up to 12 high-speed pressure transient data loggers, has been performed for over a year in the distribution system where Payment et al. conducted their epidemiological studies. The duration of monitoring was divided into 4 phases with reduced monitoring during winter time. Transient and sustained negative pressures have been measured in the distribution system due to power failures at the plant (WTP), closure of a transmission main and localized pipe repairs. Under normal system operation, a total of 9 low pressure events were recorded at the WTP during the first year of monitoring (June 2006-June 2007) resulting in 4 confirmed and 5 suspected transient negative events in the distribution system. Characterization of potential sources of microbial intrusion was also performed with the investigation of soil and water samples in pipe trenches and water samples from flooded air-and-vacuum relief valve chambers. Includes 13 references, table, figures.