Building resiliency into sewer systems with design and construction of urban flood-relief solutions to reduce surface and basement flooding

Basement Flooding Protection Program Phase 3 Implementation

The City of Toronto has historically experienced wide-spread surface and basement flooding during extreme storm events. Intense rainstorms can lead to big water problems for people’s homes, so the City developed a Basement Flooding Protection Program. They engaged our help with implementing Phase 3 of the program.

To help reduce the volume of surface and basement flooding across Toronto, we designed and implemented flood infrastructure improvement projects within flood-prone areas. During extreme storm events, large sewers must convey a significant amount of water. To better prepare the sewers, we fit large sedan-sized sewers and box culverts underground together with the existing utilities which proved challenging but not impossible. We worked with several collaborating parties to navigate, coordinate, and facilitate the design and construction of the underground infrastructure.

In total, the program included the management and design of more than $18 million (C$25 million) in constructed projects and more than $71 million (C$100 million) in storm and sanitary basement flooding improvement solutions. These included storm and sanitary inline box culvert storage solutions, outfall upgrades, and water service and watermain replacements. Our work also included utility relocation, road reconstruction, a green infrastructure bioretention raingarden feature, and a 33-foot (10-metre) -deep, 0.75-mile (1.2 kilometre) -long sanitary sewer microtunnel.

With these urban flood-relief solutions in place, the City is on their way to helping prevent excess water from damaging basements and homes in flood-prone areas.