University of Alberta: Large Diameter Twin Raw Water Intake Pipeline Inspection, Condition Assessment, and Rehabilitation

The University of Alberta’s cooling plant (CP) uses the North Saskatchewan River (NSR) water to produce chilled water used to meet the university’s cooling needs. The river water is supplied to the plant via two concrete intake structures located on the bed of the river, each connected to a wet well by a “1980 built 54-in. diameter steel pipe,” which runs under the riverbed perpendicularly to the river flow. Inspection and condition assessment efforts completed in 2020 on the 320 ft long west intake pipe revealed significant tuberculation build-up, scale deposits, multiple pinhole, and weeping leaks. The rehabilitation program started with evaluation of the technical viability and overall suitability of various rehabilitation methodologies with consideration given to all applicable characteristics of the pipe and the anticipated service life extension. Composite liner system (combining CFRP and GFRP) emerged as the most technically viable option. The rehabilitation activities were completed successfully in September 2022 to design, specifications, schedule, and budget with no safety incident.