Vancouver can't stop the rain, but it can control where it ends up

Globe and Mail

2 days ago

When the rainclouds burst over Vancouver one grey day this past winter, Lon LaClaire was delighted to see floodwater streaming into newly terraced pools on the side of a steep hill in an east-side neighbourhood.
Mr. LaClaire, Vancouver's chief engineer, is part of a team that has been working to ensure much of the city's abundant rain does not end up flooding through the sewer system, sweeping everything from road debris and toxic chemicals into surrounding waterways – False Creek, Burrard Inlet, the Fraser River – along with it.
On St. George Street, heavy rain occasionally meant closing the roadway after large amounts of rubble washed onto it. But not this time.
'We were all watching the water spill out of each of those weirs,' Mr. LaClaire said. 'Every drop of rain on St. George didn't go to the drain. It performed better than all of our other projects.'
The St. George Rainway is just one example of the new approach Vancouver and other Canadian cities are taking to stormwater management. Projects include tree trenches, permeable pavement, marsh-like areas built around sewer openings, plus rain gardens and bioswales. (The latter two are landscaped features that use vegetation to filter rainwater.) Montreal's 'sponge parks' have generated interest and praise, as have Toronto's efforts to encourage green roofs, which prevent rainwater from flowing down to the streets.
Vancouver's strategy is not just about protecting the environment. It's also a cost-saving measure, since the hope is that the city won't have to spend as much money expanding sewer lines. The St. George project cost about $1.6-million for the water-improvement part. But along with rainwater-capture requirements for new developments, it will save Vancouver $16.5-million in upgrades, according to city estimates.
'The tanks and green infrastructure are going to save us hundreds of millions in not needing larger pipes,' Mr. LaClaire said.
Vancouver's efforts have been going on for a few years, but were given a renewed push when council approved the city's Healthy Waters Plan earlier this year.
'We're super excited to see this kind of work happening,' said Emily Amon, the director of green infrastructure programs at Green Communities Canada.
'It is certainly among the leaders nationally in sustainable stormwater management. What you see in Vancouver is a more holistic approach. Often these issues elsewhere seem to be disjointed.'
As of March, the city had developed 400 infrastructure projects aimed at treating and detaining rainwater runoff from 321,000 square metres of street. These include tree trenches built alongside a downtown bike route that absorb water and allow for bigger canopy trees to grow on the street because of the extra moisture.
'The goal is to mimic the natural hydrology, the same filtering and sponge characteristic of rainforests,' said Robb Lukes, Vancouver's associate director for green infrastructure.
Mr. Lukes, who has worked in this field for 23 years, said other cities are taking similar steps. Seattle, Portland, Philadelphia and New York have been especially aggressive, with thousands of projects apiece.
But, he said, Vancouver is catching up with those American cities in terms of standardizing the approach.
'We're making it business as usual everywhere. Any big road project, we look at how to put in green infrastructure. We're a bit ahead of the curve in Canada.'
For example, any time the city installs a corner bulge – an improvement that extends the sidewalk out at intersections to make pedestrian crossings shorter – it builds in 'bioretention' instead of spending the same $20,000 to $30,000 to move the catch basin.
Even though the rainwater projects are a small part of the city's overall system so far – the 27 hectares they cover represent 1 per cent of total street area – officials are eyeing the potential financial benefits.
The council has budgeted $4-billion to spend in the next 50 years on its healthy-waters initiatives, in addition to its work to separate sanitary and storm sewers.
Larger buildings in Vancouver have been required to manage rainwater on-site for several years. The policy was expanded in January, 2024, with developers getting credit for landscaping, green roofs and water reuse systems. The recently built Deloitte office tower has a 230,000-litre holding tank in its underground parking, with the water used for flushing all of the toilets in the building.
As of July 1, all new homes require detention tanks, which will add $15,000 to $25,000 in construction costs – an expense that will likely make some people unhappy. (Detention tanks hold water temporarily. Retention tanks hold water on site so it never gets to the sewer system.)
In a first for Canada, Vancouver has also amended its building bylaw to allow people in private homes to install systems that recycle their greywater from showers, clothes washers and sinks.
Ultimately, Vancouver hopes to reduce the uncomfortably high number of sewer backups (1,242) and surface floods (2,653) it sees every year – issues that viscerally bother city engineers.
'If you look at a Metro Vancouver overflow map,' said Chris Radziminski, a city of Vancouver building-policy engineer, 'on a rainy day, it's a little bit sad.'