On November 18th, CAFES and a group of dedicated tree advocates from our network met with city staff for a "show and tell" of Ottawa's first Stormwater Tree Trench pilot project! The pilot is taking place at the intersection of Glebe Avenue and Bank Street and includes two Honey Locust trees planted in a connected tree trench with soil cells.
While the City has previously installed soil cells, this is the first pilot to incorporate stormwater infrastructure. The stormwater engineering involves inlets, pipes and catchment basins (called "Litta Traps") that direct stormwater runoff from the street into the trench. The catchment basins filter out solids, the rain water is absorbed by the soil (which also filters out metals and pollutants from the runoff), and the water gets diverted from the city drain pipes. This process allows the trees to receive adequate water meaning they won't need to be watered manually.
The pilot's location is an optimal spot given the existing Glebe Avenue Integrated Renewal project, few utility services running underground, and no overhead hydro wires to interfere with the growing trees. The effectiveness of the pilot will be determined though regular assessments of soil moisture, soil nutrients and tree health.
Many of us were surprised to see the hard landscaped asphalt and concrete that covered the underground tree trenches. According to the project manager, it was important for the site to return to its previous state, with hard surfaces for bike racks, parking meters and mailboxes, and that the hard landscaping will not impede on the rainwater being drained and absorbed into the trench.
CAFES 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. For more information, see our post about stormwater and tree trenches HERE.
The photos below show construction process before the trees were planted. The bottom three photos in the collage are from our site visit, with the last photo showing the prepared tree pit just before planting.
The following photos show the Honey Locust trees now planted in their new homes!
