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Basement Flooding Area 9 Inflow and Infiltration Reduction Pilot Project

This case study explores how our strategic intervention not only tackled these challenges but also set a benchmark for effective wastewater management.

Project Description

The City of Toronto embarked on an inflow and infiltration reduction study for Area 9, which had been grappling with systemic basement flooding during extreme rainfall since the 1950s. The I&I study was conducted to address the recommendations from the 2012 Municipal Class Environmental Assessment (EA), Schedule B, known as the “Basement Flooding Study Area 9.”

Civica Infrastructure Inc. partnered with the City to devise a solution that would meet the criteria for basement flooding protection at a minimal cost. The strategy involved:

  • Disconnecting 80% of the foundation drains linked to the sanitary system
  • Disconnecting 12 downspouts
  • Sealing 60 sanitary manholes
  • Sealing 1 basement walkout drain
  • Sealing 1 sanitary cleanout

The intervention reduced the peak I&I rate from 4.3 liters per second per hectare (L/s/ha) to 3.8 L/s/ha, demonstrating significant improvement in managing wastewater and preventing further flooding.

Relevance of Experience

This project required a robust blend of environmental monitoring and hydraulic modelling. Our expertise in flow monitoring and defect remediation analysis played a pivotal role in developing an effective strategy.

The project also highlighted the importance of resident engagement and stakeholder communication. Ensuring that the local residents were informed and cooperative was crucial to the success of interventions that involved private property inspections and other intrusive measures.

Such comprehensive experience is invaluable for any municipality or developer that is facing similar challenges.

Challenges Faced

One of the primary obstacles we faced was the high volume of residential foundation drains contributing to I&I. This challenge wasn’t unique to Toronto and is prevalent in other parts of southern Ontario. Identifying and disconnecting these drains was vital to increase the sewers’ capacity and prevent flooding.

Additionally, coordinating with multiple stakeholders, including the City and other consultants, required consistent and clear communication. We overcame these hurdles with detailed planning and execution, emphasizing the need for a well-orchestrated strategy in wastewater management projects.

Lessons Learned

The Basement Flooding Area 9 project taught us several key lessons.

  • Active and consistent communication with stakeholders is essential for project success.
  • Developing a comprehensive stakeholder communication plan helps streamline investigations involving private properties.
  • The impact of residential foundation drains on I&I is substantial, reinforcing the necessity of disconnecting them to enhance sewer capacities.

Choose Civica for Expert Inflow and Infiltration Reduction Solutions

The Basement Flooding Area 9 project in Toronto demonstrates the effectiveness of strategic interventions in managing flooding risks through stakeholder collaboration and advanced techniques. It provides practical insights for municipalities, developers, and engineers to tackle similar challenges and improve wastewater management.

To gain a deeper understanding of our inflow and infiltration strategies, including water flow monitoring systems, please contact Civica today.