When Storm Sewers Can’t Cope, ‘Sponge Cities’ Help Absorb the Overflow

While it may not have been “feasible” to prevent 300 million litres of untreated water from flowing into the Ottawa River during a record rainstorm earlier this month, cities are still catching up with the natural protection systems that can make a difference when engineered infrastructure is overwhelmed by severe weather.

When sudden storms amped up by the climate emergency get severe enough, they can and will swamp the best local defences. But the highly-touted Combined Sewer Storage Tunnel in Ottawa that opened in 2020 and hit its limit earlier this month, leading to a “mayhem” of flooded basements and health risks, was just one of the tools in the city’s toolbox for keeping floodwaters under control. Read more