Southdale Road in London, Ontario, Realizes Numerous Project Benefits with Silva Cells

The versatility of the DeepRoot Silva Cell system made it the ideal choice for soil volume, stormwater treatment, and other site priorities


A congested traffic artery in London, Ontario, Southdale Road broke ground on an improvement initiative in 2022 with the purpose of widening the lanes for both vehicular and pedestrian traffic. The design team at AECOM incorporated a green infrastructure element into the project, adding 23 street trees between Pine Valley Boulevard and Farnham Road, as well as a stretch of Bostwick Road. The DeepRoot Silva Cells were installed to provide an ideal soil-volume environment for tree root growth as well as serve as a resilient low-impact development (LID) stormwater-treatment tool on location.

Installation Summary

Number of Silva Cells: 894 (3x)

Amount of Soil Volume Per Tree:  20 m3 shared (700 ft3 )

Number of Trees: 23

Type of Project: Integrated, Stormwater, Government

Project Designer: AECOM – London

Project Contractor: Outer Construction

Installation Date of Silva Cells: 2022-2023

The Project

A major thoroughfare in London, Ontario, Southdale Road has experienced congested traffic for years as development in the area continues to grow. In 2017, a multi-phase improvement project was initiated with the purpose of widening the roadway for both vehicular and pedestrian traffic — with the addition of two car lanes as well as new sidewalks and bike paths. The first stage of the project began in 2022 and focused on the section from Pine Valley Boulevard to Farnham Road, with a small additional street section receiving attention along Bostwick Road.

Sustainability was a top priority for the new low-impact development (LID) project, as the design team at AECOM looked to not only incorporate green infrastructure into their plans, but also meet local requirements for at-source stormwater management.

Twenty-three new street trees were planted along this strip of road in late summer 2023 — and the DeepRoot Silva Cell system was utilized for its versatility, supporting the weight of the paved walkways while also providing lightly compacted soil volume for tree-root expansion. Likewise, the system serves as a stormwater-treatment tool, using stormwater runoff to irrigate the trees and reduce peak-flow drainage from overwhelming the municipal sewer system.

DeepRoot Silva Cell Success

A total of 894 (3x) Silva Cells were installed; the system will provide each tree with 20 cubic meters of shared soil volume, enough to ensure thriving root expansion for years to come. The Silva Cells, in addition to putting the trees on the path to healthy maturity, offered project planners a number of additional on-site benefits.

Perhaps the most important advantage relevant to this project was the Silva Cells’ ability to treat stormwater on site. The province of Ontario approved the use of Silva Cells for stormwater management, granting the project Environmental Compliance Approval (ECA), beholden to criteria established by the Environmental Assessment (EA). Functionally, the Silva Cells will harness the stormwater runoff from a catchment area along Southdale Road via catch-basin inlets. This process will provide the dual benefits of utilizing runoff as irrigation for the 23 street trees and assisting the municipal sewer system with stormwater cleansing and lowered peak-flow drainage.

The versatility of the Silva Cell system, combined with DeepRoot’s technical and manufacturing resources, ensured this project was a success. Given the simultaneous advantages of the Silva Cells — providing a soil environment to assist in large tree growth while also managing on-location stormwater — the system became not only convenient but affordable. Likewise, when the construction team needed additional product during the first phase of installation, DeepRoot’s local Canadian manufacturing made the turnaround time quick and painless, keeping the project on schedule with a new shipment in less than 48 hours.

The DeepRoot project leaders and technical team were involved from the beginning, assisting in several rounds of soil-volume calculations and helping get the project from concept to fruition. “Mark and Mike were very helpful in stickhandling this through the city,” notes Bill Trenouth of AECOM. “The DeepRoot team provided everything from utility bridging details to example ECAs from other projects to pre-installation site support and even a drone video. This would not have happened without the efforts of the DeepRoot team in support of AECOM engineers.”

Finally, the Silva Cell system provided enough support for the pavers and landscaping above to allow ongoing maintenance to be performed in the area, including the deployment of heavy equipment — another priority of project planners. The partnership with the city of London, the designers at AECOM, and the construction team at Outer has been seamless and DeepRoot is excited to continue monitoring the progress of this streetscape improvement initiative.

Additional Resources

Check out other DeepRoot projects in Ontario here, here, and here.


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