The Regional Municipality of York operates a significant water supply system, including approximately 360km of transmission watermain, to meet the demands of its population of over 1.2 million residents. The York-Peel feedermain, a critical watermain that supplies approximately 30% of the water demand for the Region, is comprised of 1,800mm (72in.) diameter pre-stressed concrete cylinder pipe (PCCP) constructed in 2005.
In 2022, as part of a leak detection inspection using SmartBall technology, the Region identified two leak points at Humber River crossings located within the Toronto Region Conservation Authority (TRCA) regulated area. The first leak was detected near the west portion of the Humber River near the intersection of Rutherford Road and Highway 27. The second location was east of the river, near Rutherford Road and Pine Valley Road. The west leak was severe with an estimated rate of 30L/s beneath the river and was in close proximity to the Rutherford Road bridge crossing.
In October 2022, the Region retained TYLin and Robinson Consultants Inc. to undertake a comprehensive and expeditious evaluation of solutions, ultimately selecting Carbon Fibre Reinforced Polymer (CFRP) lining as the preferred option. This critical decision was based on a review of available technologies for transmission mains of similar size, the watermain’s operating pressure and geometry, associated access challenges, as well as the restricted time frame to complete the repair. CFRP is commonly used for structural rehabilitation, retrofitting, and strengthening of various infrastructure elements such as beams, columns, walls, bridges, and pipelines. The technique provided a cost-effective solution to enhance the structural integrity and extend the service life of aging or damaged structures.
The feedermain had limited redundancy, so the leak repairs needed to be undertaken with the feedermain shut down during the winter months and had to be back online to meet peak spring demand. The project required extensive effort, with long shifts and a large number of workers involved. At peak, crews were applying 61m (200ft) of two liner thickness per day, which is a very efficient application for CFRP. Successfully completing this repair within the given timeframe was critical in minimizing additional stress on the existing water supply system. It was also a significant challenge, given that typical repair work of large feedermains like the York-Peel can take up to 1-2 years to complete.
Overall, 7km of pipe was decommissioned and recommissioned, totalling approximately 18,000m³ of water. During the draining of the feedermain, the water was neutralized using sodium thiosulphate prior to pumping it into energy dissipation pools and monitored to ensure no adverse impacts to the nearby Humber River systems. Once dewatered, the team completed an internal visual inspection of the pipe to determine the extent of the rehabilitation required.
Approximately 370m (1,215ft) of the feedermain was rehabilitated with CFRP to provide a long-term solution for the critical watermain. The contractor completed infrastructure modifications to provide access to the watermain in November/December 2023. The pipe rehabilitation commenced in January 2023 and was completed in March 2023. The feedermain was recommissioned and back online the first week of April 2023.
