Emergency Rehabilitation of Critical Water Main in Ottawa

In 2021, the City of Ottawa (Ottawa) managed an urgent repair to their 1,200-mm Woodroffe Water Main, ensuring continued safe and reliable pipeline operation. They were alerted to an increased rate of deterioration via their acoustic fiber optic (AFO) system that has been installed since 2011 to monitor the pipeline for wire breaks in near real time. The Woodroffe Water Main is comprised of prestressed concrete cylinder pipe (PCCP), for which wire break is an indicator of deterioration. In February 2021, an increase in wire breaks was observed at two pipe sections. Ottawa has performance curves based on finite element analysis, for the Woodroffe Water Main, which provide a threshold number of wire breaks for rehabilitation recommendations. While the two pipes were still below the threshold, the breaks were occurring quickly and Ottawa had to consider the limited time options for taking the pipeline out of service for repair with respect to upcoming projects. The pipe sections were under a culvert, making excavation extremely difficult; therefore an internal repair method was required. Ultimately, Ottawa decided to move forward with rehabilitation using internal carbon fiber reinforced polymer. This paper presents the planning, challenges, and decision making that took place from the time of increased break activity to the completion of the repair. The results of this rehabilitation allowed Ottawa to continue confidently utilizing this water main.