Why is it taking so long to open that last stretch of the Rideau Canal Skateway?
Most of the 7.8-kilometre skating rink opened this week, but one section remains closed
After two disappointing seasons, skaters have been flocking to Ottawa's Rideau Canal since one section opened on Saturday, followed by a second stretch on Tuesday.
But one perennially stubborn section of the 7.8-kilometre skateway remains off limits: that final 400 metres between Laurier Avenue W. and the National Arts Centre.
"That section is the most challenging one because it combines all the worst conditions we can have on the canal," said Patrick Laliberté, the National Capital Commission's (NCC) director of Ontario urban lands and Greenbelt.
"It's narrow, we have bridges, there's a lot of concrete in the environment, we have stormwater drains, so we have to adjust to that."
That northernmost section has failed to open for three of the last five seasons, including 2022-23 when poor weather conditions prevented the skateway from opening at all — a first in its history.
Warm runoff 'the main issue'
According to Shawn Kenny, a civil and environmental engineering professor at Carleton University who has been working with the NCC to mitigate the effects of climate change on the skateway, the main culprit preventing that final section from opening is a stormwater drain between the Laurier and Mackenzie King bridges, adjacent to Confederation Park.
"That's the main issue there," Kenny confirmed.
While he's not entirely sure about the source of the runoff, Kenny said the temperature of the water flowing into the canal at that location is about five to 10 C. He said the NCC attempted several years ago to mitigate the effect on the ice surface by siphoning the runoff through a series of pipes toward the middle of the canal, but with limited success.
The result is a thinner ice surface that's much more difficult to prepare and maintain than other sections of the skateway.
"It's not an easy problem for them to solve," Kenny said.
He said a similar stormwater drain near Somerset Street W. is less problematic, but an area near that drain remains fenced off most winters.
Other factors
There are other factors, including a concentration of bridge infrastructure and other concrete objects that can cause a "natural heat island-type effect," which can be witnessed early in the season when ice is slow to form in those areas, Kenny said.
The runoff flowing into the canal may also contain higher levels of salt, though Kenny said that's unlikely to pose a significant problem when it comes to the ice surface.
On its website, the NCC says the skateway faces several "urban pressures" including surface water runoff, salt intrusion, heat from underground pipes and variations in the canal's depth. All of these factors can influence "the heat and energy balance from the mudline to the ice cover."
The NCC says it's working with Kenny and his team at Carleton on a number of innovative solutions to address the effects of climate change including slush cannons, thermosyphons and "enhanced snow management."