Ottawa pilots the first stormwater trench in the Glebe

Ottawa pilots the first stormwater trench in the Glebe
By Della Wilkinson
Glebe residents may have been curious about the big trench that was dug along the side of Shoppers Drug Mart this fall. It’s Ottawa’s first stormwater tree trench.
On November 18, City of Ottawa staff from stormwater management and forestry invited residents to learn about the project on Glebe Avenue at Bank Street. It turns out that this location was optimal because there were few services running underground through the site and no overhead wires to interfere with the growth of the two native trees that will eventually be planted there. In addition, the work could be added to the ongoing Glebe Avenue Integrated Renewal to limit costs to taxpayers since the expertise and equipment were already in place.
While the City has installed tree trenches with soil cells, this pilot is the first to incorporate stormwater infrastructure. The plan involves planting two drought- and salt-tolerant Honey Locust trees in soil cells with stormwater engineering (pipes, inlets, catchment basins) to direct road run-off into the trench to be absorbed by the soil, thereby absorbing rainwater where it falls, filtering pollutants from run-off and diverting water from storm drains, all while watering the trees. The catchment basins can handle rainfalls of up to 27 millimetres before releasing excess water into the drain system.
The water from the road runoff and the soil cell’s 60 cubic metres of organic-rich soil will allow the trees to grow to full height and clean our air for up to 100 years or more, even in this dense urban environment. The trees won’t need additional water – the road runoff will give them everything they need. Soil nutrients can be replenished by the road runoff or by natural organics or fertilizer at the open soil area around each tree. The plastic supports inside the soil cell will keep the soil from being compacted and allow the tree roots to happily spread out.
The meeting was organized by the Community Associations for Environmental Sustainability (CAFES) which has been a long-term advocate for the installation of stormwater tree trenches and for overall stronger linkages between green infrastructure and stormwater management in Ottawa.
I was imagining a system designed to absorb stormwater to be more like a garden bed, so I was surprised by the non-permeable asphalt and concrete slabs. I learned that all the magic happens below the surface inside the soil cell. The project manager, Jeff DeLoyde, explained that the site was being returned to its original state, which included space for public art, three bike racks, a post box, a parking ticket dispenser and, most importantly, a Glebe Report newspaper box.
Contact us at environment@glebeca.ca. Follow us on Instagram @gcaenviro175.
Della Wilkinson is chair of the Glebe Community Association Environment Committee.