More room for roots makes for happier, healthier Columbia Ave. trees

Andrew Bennett
By Andrew Bennett
August 2nd, 2012

Big stacks of large black lego—or so it looked—were installed last week along the south side of Columbia. The multifunctional blocks are “Stratacells” as assistant city planner Stacey Lightbourne explained.

“I’m not the expert,” she began, deferring to ISL engineers and landscape architects for the details, “but it’s a fairly new, proven way of housing tree roots. It holds soil, and allows tree roots to expand as they wish through the cells.”


Trees planted beside sidewalks typically have to squeeze their roots into a small space of hard packed gravels. Over time, the sidewalk often suffers as the roots fill up the available space and push up on the concrete, cracking it, lifting it, or distorting the surface. When the tree runs out of space, often in a short period of time, they can no longer sustain themselves, suffer poor health, and decay.


Stratacells provide equal strength for the road or sidewalk above as provided by a granular bed, but the cells create a void that can be filled by roots and fluffy topsoil. The result is street trees that grow better and live longer.


It’s not just about tree health, however. The cells also make an easy route for pipes and ducting, and give much easier access to the pipes than other options if repairs and additions are required. 


The stack of Stratacells is 1.5 metres wide by 1 metre deep, and will go the full length of both sides of the street, Lightbourne said. Concrete pavers will rest directly on top. “You’ll never know they’re there,” she said.


“The concrete pavers are easy to lift up to access the cells,” Lightbourne explained. “It’s very easy access if we ever wanted to lay anything else in there.” She said the irrigation, street lighting, and fibre optic conduit will be run through the Stratacells.


Lightbourne said the city wasn’t immediately convinced when ISL Engineering—the company Rossland hired to design and build the Columbia Avenue infrastructure renovations—originally suggested Stratacells. “There were big discussions: ‘It’s really expensive, do we really want to or need to?'” she said. But in the end, everyone agreed it was the “way to go” for trees, pipes, and long term sustainability.


Stratacells will be installed on the north side of Columbia after services are run to the businesses there. The south side was installed already since these businesses have services come in off the alley, Lightbourne explained.


For more information, we’ve attached the technical information sheet for the Stratacell from its supplier, Citygreen Landscape Solutions.

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