Trunk Water Main Failure Consequence Modelling During Normal, Peak and Fire Flow Conditions

Abstract

Trunk water main failures pose a large risk to users as they often carry severe hydraulic, economic, and social consequences. The consequences can be increased when a fire event in the water distribution system coincides with a trunk water main failure event. Currently, municipalities have limited knowledge on the consequences associated with the failure of trunk water mains, as it has only recently emerged as an area of concern as water main assets reach or exceed their expected service life. Consequence modelling can provide municipalities with information to help with emergency planning and rehabilitation/replacement planning. The aim of this thesis is to present a new methodology to characterize the consequences of trunk water main failures in water distribution systems. A new consequence index equation is used to calculate the severity of a failure event. A number of metrics were developed to characterize a range of consequences to the system and water users. A focus is placed on the hydraulic changes during water main failures and the ensuing consequences. The model examines failure during normal, peak and fire flow conditions in the network. Two case studies were completed by applying the consequence model to the D-Town and City of Kingston water distribution systems. The purpose of these studies is to demonstrate the effectiveness of consequence modelling and provide the City of Kingston with information regarding trunk water main failures in their system, and thus help prevent high consequence events. An investigation of the relationship between pipe properties (location, pipe diameter, pipe length, proximity to large components) and consequence severity provided insight into trunk water main failure events. The results of these studies suggest that the location of the trunk water main failure is the largest contributing factors to the severity of consequence.