When Storm Sewers Can’t Cope, ‘Sponge Cities’ Help Absorb the Overflow
Sourced from The Energy Mix
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.
Stormwater management expert Jenn Drake, an associate professor in the Carleton University school of engineering, told CBC the system has reduced the volume of sewage flushed into the river “by orders of magnitude”, but it would cost billions and take decades to rebuild that infrastructure to account for extreme storms—if the system could be rebuilt at all.
“When you think of the environmental implications of that polluted water that was just going directly into one of the most important rivers in Canada,” Drake said, “we’ve achieved something quite significant.” But in many cities, “it is not feasible, affordable, practical” to engineer a stormwater system so big that no storm will push it beyond its capacity.
From the Living Architecture Monitor
