December 14, 2017 by Saul Chernos
With scientists forecasting increasingly turbulent weather, builders developers and governments can expect heightened pressure in 2018 to green their infrastructure.
The Ontario Ministry of Environment and Climate Change, for instance, is developing new measures for stormwater run-off volume control.
“It will require that in any new construction or redevelopment work all projects will have to manage on-site the 90th percentile of rainfall events,” said Clara Blakelock of Green Communities Canada. That translates into about the first 25 millimetres of rain, depending on exactly where you are in the province, she explained.
The problem is twofold. Water carried off-site doesn’t recharge local water tables, and heavy rains sweep debris, residues and other waste into waterways.
Ontario’s rules date to the 1990s and acknowledge the importance of managing rain on-site. But the province has still been approving catch basins and storm sewers. “Now they’re coming back and saying people really need to change the way they’re doing things,” Blakelock said. “There’s pretty strong language about what’s going to be required for new developments.”
British Columbia is also promoting stormwater management on-site, and municipalities are also getting on-board. Vancouver has just come out with a strategy to manage 90 per cent of its rainfall close to where it falls, Toronto has a green roof bylaw and other guidelines, and Halifax and Kitchener, Ont. charge stormwater fees based on a property’s impervious area.
“A lot of communities get their drinking water from groundwater aquifers, so if these aren’t being recharged through infiltration then they can start to dry up,” Blakelock said. “And the pollution from runoff closes beaches and affects fishing, tourism and drinking water.”
Tangible measures include permeable pavement and trees as well as landscaping such as rain gardens and bioswales. “Underground infiltration galleries can be completely invisible underneath a parking lot,” Blakelock said.
Green infrastructure can increase property values, make streets more walkable, improve air quality, provide habitat for pollinators, reduce the urban heat island effect and help mitigate huge costs arising from storm damage.
“Cities across the country are seeing increased flooding and other impacts,” Blakelock said. “These are ways of building resiliency into our cities.”