Newmarket Inflow and Infiltration Reduction Project: Marianneville Developments Limited

For the Town of Newmarket, excessive inflow and infiltration (I/I) in sanitary sewer systems not only strained infrastructure but also increased costs and risks associated with sewage management. The Town, in partnership with Civica Infrastructure Inc., addressed these challenges through an extensive inflow and infiltration reduction project that delivered measurable results.

This case study explores the project’s scope, challenges, and lessons learned, offering valuable insights into best practices for municipalities and developers tackling I/I issues.

Project Description

Civica undertook a large-scale inflow and infiltration reduction project in Newmarket designed to identify and mitigate I/I sources. The project included several key investigative techniques such as:

• Smoke testing of over 100 kilometers of sanitary pipes
• Dye testing of more than 6,500 features
• Flow monitoring across the area of concern

By prioritizing sanitary sewer evaluation surveys, the project team identified the highest-priority I/I sources. Remediation efforts focused on both public and private I/I contributors, including sanitary pipe infiltration fixes, maintenance hole (MH) remediation, and the disconnection of private-property I/I sources.

Specific private-property remediation included disconnecting downspouts, sump pumps, driveway drains, and commercial roof drains. These efforts effectively reduced peak flow and overall volume in the Town and Region’s sanitary sewer systems, providing long-term relief to critical infrastructure.

Relevance of Experience

This project demonstrates the successful application of comprehensive I/I management practices across several disciplines. Civica’s key areas of expertise included:

• Environmental monitoring and hydraulic modelling for accurate flood analysis
• I/I analysis using flow monitoring and data integration
• Investigative methods such as CCTV sewer inspections, MH inspections, smoke testing, and wet weather inspections
• Stakeholder engagement for seamless implementation across public and private properties

The multidisciplinary approach ensured the identification of critical I/I contributors and actionable recommendations to enhance sewage water management for municipalities downstream.

Challenges Faced

Several challenges required innovative solutions throughout the project:

Stakeholder Communication: Engaging multiple stakeholders, including the Town of Newmarket, third-party consultants, and private property owners, involved careful coordination. A lack of alignment among all parties could have delayed or compromised outcomes.

Residential Foundation Drains: Foundation drains represented a significant contributor to I/I in Newmarket. Their comprehensive disconnection posed both technical and logistical challenges, especially on private property.

Inspection Access & Participation: Conducting smoke and dye testing or accessing private lots required strong buy-in from residents, which demanded a robust communication strategy and thoughtful planning.

Lessons Learned

The collaboration yielded several critical lessons that can inform future I/I reduction projects:

Proactive Stakeholder Communication: Consistent engagement with municipalities, consultants, and property owners ensures smoother implementation and minimizes delays throughout the project lifecycle.

Foundation Drain Mitigation: Residential foundation drains remain a major contributor to I/I across southern Ontario. Disconnection of these drains can significantly increase the residual capacity of sewer infrastructure downstream.

Strategic Private Property Engagement: A stakeholder communication plan is essential for inspections such as smoke and dye testing or foundation drain evaluations. Including warranty periods for private-property remediation further enhances stakeholder satisfaction.

Support for Innovation: Municipalities providing incentives for testing new techniques and tools are better positioned to adopt innovative I/I reduction measures.

Making Strides in I/I Reduction

Civica’s work highlights how comprehensive inflow and infiltration inspections and remediation efforts bring critical benefits, from flood prevention to infrastructure resilience. Municipalities, land developers, and civil engineers can learn from this project to implement smart solutions for I/I challenges in their own regions.

To discover how your future projects can achieve sustainable improvements in urban water management systems, please contact Civica today.