The Region of Ottawa-Carleton (ROC) has more than 900 kilometers of ductile iron main and more than 800 kilometers of cast iron lined main in the water infrastructure along with approximately 28,000 valves. Some of the ductile iron pipe installed in 1971 to 1989 already shows signs of corrosion and failure. The rehabilitation program could not replace the water main at the rate required to maintain a minimal backlog of rehabilitation work. This would compromise the infrastructure quality and lead to more reactive programs, than to the more proactive approach. It is imperative to identify methods of prolonging the water main and valve life either indefinitely or until replacement of the main and / or valves could be completed in a cost-effective manner. The Region reviewed various methods that other cities had adopted as their programs to defer the rehabilitation of these water mains. Test sites and different methods were developed to ensure the best practice method was implemented.
Keywords: ductile iron, cast iron, corrosion, cathodic protection, exothermic weld, water pipes