Downtown tree wells turned from grates to great

Question: what do you get when you combine accessibility, safety, beauty and cost effectiveness?

Answer: new tree surrounds in downtown Lethbridge!

Some of the older tree grates were breaking, or the trees were being girdled. (That’s when the base of the tree is being choked because it has grown too large for its grate. It reduces nutrient flow and can cause significant harm to a tree.) Safety was also an issue. Some grates presented tripping hazards, as large tree roots had lifted them above the sidewalk.

Previous attempts to replace the grates weren’t overly successful.

“A pour-in-place rubber surfacing was installed in a few tree grates,” says Justin Schipper, Urban Revitalization Administrator. “But the rubber material was only semi-permeable, didn’t remain level and the colour faded over time.”

This summer, the Urban Revitalization and Parks departments collaborated on a pilot project to find a new solution. A bonded aggregate solution, to be exact!

A clear resin is mixed with pea gravel and poured into place at the base of the tree. The mixture is levelled, then the resin hardens and bonds the edges of the aggregate together. (Science for the win!)

“The solution is very permeable,” says Erin McIlwraith, Parks Operation Coordinator. “This allows the trees to access much-needed water when it rains.”

Accessibility and cost were two factors in the pilot project. The teams found a solution to both.

“The aggregate is fully accessible,” says McIlwraith. “A wheelchair easily passes over the installs.”

“The installed price of the bonded aggregate is about five per cent of what a new tree grate costs,” notes Schipper. “Our internal amenities crew completed the installations. That avoided the cost of hiring outside contractors.”

McIlwraith calls the project a shining example of successful collaboration. She also says the work is being well-received.

“I've had many conversations with the public. The overwhelming sentiment has been positive, especially about the aesthetic appeal.”

The pilot project saw approximately 20 tree wells upgraded in the downtown this summer. Another 100 trees are expected to be completed in the coming years.

For Public Inquiries:
Call 311 | Monday to Friday, 8 a.m. to 4:30 p.m.