Extending the Life of RAS Piping for the City of Winnipeg

The City of Winnipeg (city) has undertaken a large-scale rehabilitation of their North End Sewage Treatment Plant. An integral component of this rehabilitation project was the in situ structural renewal of 1,640 LF (500 m) of in-service return activated sludge (RAS) process piping with several active leaks. The city engaged Kontzamanis Graumann Smith MacMillian Inc., Group (KGS Group) as the project’s engineering consultant to evaluate options for strengthening the RAS piping, which range in diameter from 12 in. (300 mm) to 36 in. (900 mm). The city and KGS Group selected external carbon fiber reinforced polymer (CFRP) as the rehabilitation method. The CFRP subcontractor, Pullman, mobilized to the project in April 2022 and worked collaboratively alongside the city, KGS, Simpson, Gumpertz and Heger (SGH), and the general contractor—Trotter and Morton. As was expected, the project details evolved frequently in response to as found condition. SGH utilized an in-field engineer and an iterative design process to minimize project delays. The collective team met frequently to resolve these RFIs in a timely fashion. The CFRP component of the project was completed on time with change orders accounting for less than 1% of contract value.