“The Town of Banff proceeded with the use of Silva Cells in the project due to the dual use of stormwater treatment and supporting tree growth in a downtown area.”
Situated within Canada’s oldest National Park, the Town of Banff underwent an ambitious $9.5 million eco-makeover project in 2020 with the goal of reflecting the natural beauty of the wilderness in the downtown area. A total of 92 trees were incorporated along Bear Street, where developers envisioned a shared streetscape that prioritized pedestrian traffic rather than road vehicles. Nearly 700 DeepRoot Silva Cells were installed onsite, serving to provide the trees with a healthy soil volume environment, act as a source control for stormwater management, and allow space for the newly upgraded underground utility network. The project successfully concluded in 2021, now a gorgeous tourist attraction streetscape boasting four 2022 awards.
Number of Silva Cells: 687 (3X / 2X / 1X)
Total Soil Volume: 23,536 ft3 (666 m3 )
Number of Trees and Type: 92 (coniferous and deciduous)
Type of Project: Integrated Trees and Irrigation
Project Contractor: Bremner Engineering & Construction Ltd.
Installation Date of Silva Cells: 2020
Project Timeline: 2020-2021
Three to four million visitors a year grace the majesty of Banff National Park in Alberta, Canada. The Town of Banff, situated within the park itself, is home to just 8,000 residents – but its tourist industry, including quaint shops and restaurants, thrives along the downtown Bear Street thoroughfare.
Project planners for the Bear Street eco-makeover initiative, which broke ground in 2020, prioritized pedestrian-friendly streetscape elements: a common, curb-free space shared by walkers, bikers, and vehicles. “We want the vehicle to feel like a guest and for the pedestrian to be king on the street,” noted Darren Enns, the planning director for the Town of Banff.
A total of 92 coniferous and deciduous tree were also incorporated into the streetscape design – a way for the downtown area to reflect the majesty of the surrounding National Park and to offer visitors a pleasant, inviting atmosphere. Providing that many trees with adequate soil volume for healthy growth, in addition to assisting with at-source stormwater treatment and integrating a new underground utility network, presented a number of shared-space challenges for the project planning team.
Designers at WSP and The Tula Project turned to the DeepRoot Silva Cell system.
“WSP, The Tula Project, and DeepRoot’s collaborative design approach was applied to Bear Street in the Town of Banff as an alternative way to reduce, manage, and treat stormwater prior to the ultimate outfall at the Bow River, while providing sufficient uncompacted soil volumes for tree growth,” observed Jessica Wheatley (P.Eng. PMP at WSP) and Kelsi Hurlburt (principal LA at The Tula Project). “The Town of Banff proceeded with use of the Silva Cells in the project due to the dual use of stormwater treatment and supporting tree growth in a downtown area.”
In total, 687 Silva Cells (1X, 2X, and 3X) were installed by Bremner Engineering and Construction Ltd. The system provides a total of 666 cubic meters (23,500 cubic feet) of uncompacted soil volume for prosperous root growth.
All 687 Silva Cells and the adjacent planters collect stormwater from trench drains, filter it, irrigate the 92 new trees and all landscaping, and clean drainage before allowing it to flow into the stormwater system. Installed about 400mm below ground, the Silva Cells are providing 4X the amount of soil than traditional open planters.
There are moisture sensors in the planters as well as in the Silva Cells. The moisture sensors connect to the irrigation system to tell it when to turn on during drought periods. Subsurface drip irrigation was introduced below the paver in the Silva Cell areas to maintain saturation under the pavers and promote root growth into the Silva Cells. The drip irrigation is on a different circuit than the planters so there are moisture sensors tracking each space.
Finally, project planners had to replace the century-old sewer and water pipes as well as other utilities. The Silva Cell’s unique design made any future access or repair of existing/new utilities easy — which allowed the city to integrate utilities with and below the Silva Cells.
Ultimately, due in no small measure to the multiple, simultaneous green infrastructure benefits provided by the DeepRoot Silva Cells, Bear Street is a flourishing streetscape and multiple award winner, taking home four prizes in 2022 including Water’s Next Project of the Year.
-Award of Excellence, Planning Design and Construction (2022 International Downtown Association)
Main photo courtesy of Helen Pike