“Throughout the design process, Brook McIlroy [helped] everyone understand the benefit of a healthy urban tree canopy and green infrastructure, including the benefits of technology… such as Silva Cells.”
The town of Oakville, situated on Lake Ontario’s waterfront, began preparations for a restoration project on Lakeshore Avenue beginning in 2006. In the following years, the multi-phase improvement initiative began to take shape with sustainable urban forestry as one of its primary objectives. Utilization of the DeepRoot Silva Cells was integral, as they provided adequate soil volume (to meet newly established local standards), had the flexibility to work within underground utilities, and provided stormwater management to assist with 100-year flood events. The Silva Cells would help create a healthy environment for the 82 new trees with a goal of 40% canopy coverage by 2027.
Number of Silva Cells: 1,656 3X
Amount of Soil Volume Per Tree: 21m3 (1,758 total m3 )
Number of Trees and Type: 82
Type of Project: Integrated Trees, Stormwater
Project Designer: Brook McIlroy
Project Contractor: CRCE Construction
Installation Date of Silva Cells: 2018-2020
Project Timeline: 2013-2020
Lakeshore Drive is one of the primary thoroughfares in downtown Oakville, home to numerous restaurants, coffee shops, retail outlets, and tech stores. As discussions for the revitalization project of this main city artery began, green infrastructure was at the forefront of design plans with the newly passed Urban Forest Management Plan (UFMP), setting key design goals.
The UFMP included a roadmap for creating a minimum 40% canopy coverage by 2027. The key mechanism to achieving this target was the implementation of a Street Tree Soil Volume Standard. In 2009, Oakville also passed into law an ordnance that trees shall be protected and treated as green infrastructure.
City councilman Allan Elgar appreciates the change in municipal values. “It has become clear to many of us that Oakville’s trees were not doing well. They might live 20 or 30 years, but they’d remain small and root-bound, and then they’d die. Once we learned how much more we could be doing, it was obvious to us that had to move in that direction.”
Using the Toronto Green Standard of 30 cubic meters of soil volume per tree, as well as their own extensive studies on urban forestry and sustainability initiatives, a streetscape master plan was developed in 2013. “From the beginning, sustainability and rejuvenation were the main points for the downtown project in Oakville,” recalls Colin Berman from the landscape architecture firm Brook McIlroy. “The project team sought to utilize green infrastructure wherever feasible.”
In parallel with the urban forestry element of the improvement process, the city’s underground utilities were also due for an upgrade. Given all of the various project priorities, it was important to find a sustainability partner that could help achieve their goals while working with the practical concerns of utility placement.
The DeepRoot Silva Cell answered the call.
A total of 1,633 Silva Cells were ultimately installed on Lakeshore Drive, the foundation for 82 newly planted trees with their 1,758 total cubic meters of soil volume – more than meeting the local standards as outlined in the project design plans. Colin Berman identifies the Silva Cells as an indispensable technological element in the initiative: “Throughout the design process, Brook McIlroy worked closely with the community to help everyone understand the benefit of a healthy urban tree canopy and green infrastructure, including the benefits of technology currently on the market, such as Silva Cells.”
The Silva Cell system was also able to incorporate seamlessly into the utility upgrade. After a century of use, Oakville’s underground infrastructure – including pipes, sewers, and other utilities – were ready for revitalization. The city used the utility upgrade as an opportunity to simultaneously improve the street tree canopy, which creates a positive feedback loop of sustained human and environmental health for another century.
“The need to upgrade utilities – which allowed for relocations to make room for the Silva Cells – was a huge driver in enabling this green infrastructure project,” says Berman. All of the project teams (including gas, hydro, electric, telecom, etc.) were on the same page to guarantee achievement of their desired result: an upgraded utility network that integrated harmoniously into the DeepRoot Silva Cell system.
Finally, Oakville’s topography and geography were factors in the project’s design and construction phase. Bordering Sixteen Mile Creek and Lake Ontario presents a vulnerability to flooding from a significant, 100-year rain event. With climate change creating more frequent, unseasonal flooding (as well as more intense storms), the Silva Cell-connected trench drains provided not only a solution for everyday rain, but also excess capacity and resilience to the grey infrastructure. Stormwater runoff is redirected through trench drains into the Silva Cells below the sidewalk, which are full of large volumes of lightly compacted soil. The Silva Cells provide peak flow reduction retention, detention, and storage services as they infilitrate stormwater before the surplus enters the municipal stormwater system.
Ultimately, this multi-phase project has yielded an improvement in traffic, an upgraded utility network, and a beautifully inviting cityscape with access for pedestrians and bicyclists. The 82 new trees are providing a healthy green canopy to Lakeshore Drive made possible by the DeepRoot Silva Cells which provide stormwater services and large volumes of lightly compacted soil to support a healthy urban forest.
The director of Engineering and Construction noted, “The Lakeshore Road project is complex, involving multiple contractors working together to complete the work required by the Town, Halton Region, Union Gas, and Oakville Hyrdo.” CRCE, the landscape contractor responsible for installing the Silva Cells, was able to coordinate with the consultants and the utilities to integrate the Silva Cells seamlessly into the public realm.
DeepRoot Silva Cells are approved as an equivalency of bioretention in Ontario. For a list of all DeepRoot stormwater approvals, please see here.