Using Cathodic Protection (CP) Retrofits to Extend Useful Water Main Life for Cast and Ductile Iron Mains

Water main replacement programs in North America have been largely focused on cast and ductile iron water mains. It has been estimated that an investment of $0.5 trillion in the next 25 years and over $1 trillion in the next 40 is required to address end of useful life requirements for these systems. The capital cost of alternative lining programs can be very close to full replacement cost and the available technologies are still evolving. There is considerable need to develop more cost effective techniques for water main rehabilitation in conjunction with optimizing replacement and structural relining techniques. A unique addition to the rehabilitation “tool-box” should be the strategic use of CP retrofit techniques to mitigate failure rates and extend useful design life of existing mains. While the cost of this approach can be highly variable based on the logistics to access the mains; it is often only 5%–10% of the capital cost of replacement or fully structural liners with comparable failure reduction when the overall system effects are considered. The paper examines the technical approach for and the effectiveness of cathodic protection in Toronto, ON, Canada, based on 40 years of implementation.