Keeping Rain Flowing in the Right Direction: A Stormwater Trunk Sewer Rehabilitation Case Study

A 1 km (~3,300 lf) long section of the North York Stormwater Trunk Sewer (STS), a 3,000 mm (118”) diameter corrugated metal pipe that services approximately 800 ha in Toronto, Ontario, has sections that are in poor condition to near failure and needs timely repairs. The culvert was built along an existing tributary to Black Creek, which resulted in a highly irregular alignment, that includes frequent sharp vertical bends and horizontal sweeps. Additionally, the culvert was constructed in several phases over a period of approximately 20 years as a result consists of multi-plate and CMP products lined with various products (tar, shotcrete, and concrete). This paper will summarize the design phase of the project to rehabilitate the deteriorating sewer, which included selecting the optimal rehabilitation methods, and producing designs and implementation plans to suit the site conditions and pipe geometry.