Civica Infrastructure Inc. is a leading provider of wastewater and stormwater management solutions throughout southern Ontario. Specializing in inflow and infiltration (I/I) prevention, we provide guidance to regional municipalities on how best to address any potential defects in collection and drainage systems.
Civica won a Professional Engineers Award for one such project in 2021. Launched in 2015, the new subdivision I/I prevention project saw Civica partner with York Region to create guidelines and standards around new subdivision wastewater system construction, testing, and inspection, while also monitoring wastewater flows to ensure new developments were not contributing high levels of I/I prior to municipal assumption.
In the wastewater system, I/I pose limitations to vital capacity, impose high costs for repairs, and hinder sustainable community growth.
Project Summary
The new subdivision I/I prevention project aimed to promote engineering best practices in sewer construction and innovative low-flow monitoring techniques, with a goal to prevent current and future I/I issues such as basement flooding, environmental spills, and sewer overload.
In the project, flow monitoring (a traditional technique) was used to assess I/I during infrastructure construction and measure water conservation and wastewater I/I prevention after homes were connected to the wastewater pipes.
Over 35 new subdivisions in York Region took part in the project. Among the new subdivisions that completed the flow monitoring portion, preliminary analysis shows that more than 80% have shown a conforming I/I response and are on their way to complete the program.
Project Description
This program combined a variety of engineering applications, principles, and elements to deliver measurable results. Measuring new subdivision low-flow accurately was especially vital for the project, and continuous improvement in flow monitoring and the creation of construction guidelines for new subdivisions contributed to innovation.
While traditional flow monitoring techniques have been used in existing neighbourhood monitoring to assess wastewater system capacity for short- and long-term infrastructure planning, these techniques could not be directly applied to new subdivisions. The small size of the subdivisions, as well as water conservation and wastewater reduction measures implemented, resulted in much lower flows. To accurately assess system flows in these low-flow conditions, new technologies, techniques, and analysis methodologies were implemented.
New flow monitoring configurations and analysis methods addressed the challenges posed by flow monitoring in very low-flow conditions. While area-velocity sensors and a traditional V-notch weir are suitable for most flow monitoring situations, the construction of a modified weir was necessary to properly measure flow in the very low-flow conditions of new subdivisions, especially during construction and before home connection.
Project Deliverables
For the Municipality:
As a result of the project, York Region can expect a long-term reduction in I/I in the sewer infrastructure, leading to sustainable development. Issues that stem from I/I can be expensive. By preventing future I/I, the municipality can save tax dollars, speed up residential land development, and stimulate population growth and job creation.
For the Development Community:
Developers will be able to service new developments, construct homes in a reasonable time-frame, and bring in revenue for both the local economy and themselves.
Challenges
- Identifying and utilizing the appropriate tools and techniques for data collection: The traditional weir with a V-notch setup faced a recurring problem of clogging, thanks to the low-flow velocity that failed to clear the debris. This issue causes inaccurate flow readings. However, a new box weir configuration was introduced that not only captures high-resolution low flow data, but also allows debris to pass through.Â
- The drainage area size of each subdivision to the wastewater system: In new subdivisions, the drainage area for flow monitoring is limited to its boundary, and it may not drain to a single outlet. Therefore, multiple monitors might be required to properly isolate homes built by one developer versus another. This results in very small drainage areas and very low sewage flow. Since low-flow monitoring is sensitive to day-to-day flow variances, it can be susceptible to noise.
- COVID-19 considerations: With the shift to remote work, Civica had to implement additional safety measures during regular maintenance visits to ensure the safety of their field staff. The pandemic had a trickle effect on the project, leading to cumulative delays that impacted project completion dates.
Impact on York Region and/or its Neighbouring Communities (GTA)
The program has shown promising results, with over 35 new subdivisions in York Region participating. It has facilitated rapid residential land development, community creation, and job opportunities.
York Region is viewed as an environmental custodian and leader in innovative system capacity management, with environmental sustainability and social economics benefiting from the program. Other regions and municipalities have expressed serious interest in implementing their own new subdivision I/I prevention programs. The Township of King is currently developing their own program, while Peel Region and Halton Region have initiated the process of creating their own versions. Municipalities can utilize programs like this to drive sustainable growth within their communities.
Choose Civica for Expert Inflow and Infiltration (I/I) Reduction
The Regional Municipality of York led the way in creating new standards and innovative flow monitoring techniques through this new subdivision I/I prevention project, which has grown and attracted other municipalities in southern Ontario to follow suit.
An industry leader in municipal wastewater management, Civica provides a variety of inflow and infiltration inspection services—from sewer camera inspection to sewer flow monitoring services. Contact their expert team of wastewater consultants today for more information.
Learn more at:
New Subdivision Flow Monitoring to Assess Performance of I/I Prevention
Challenges in New Subdivision Flow Monitoring
Methodology of Sanitary Maintenance Hole Inflow and Infiltration
Flow Monitoring in Collection System Modelling
Find Inflow and Infiltration (I&I) with Wet Weather Inspections
Sewer Flow Monitoring – Open Channel Flow Measurement Techniques
