001-43_EJQR9_SUMMER26_PT - Flipbook - Page 23
Getting greener in support of grey
Sandwiched between the Rocky Mountains and the Paci昀椀c Ocean, urban
sprawl has never been an option for the City of Vancouver. And as a result,
has one of the most intense densi昀椀cation pushes of any Canadian city.
The Broadway Plan alone envisions adding up to 30,000 new homes with
approximately 150 tower projects already in the pipeline.
It’s a plan that potentially translates into less impervious surfaces for rainwater to in昀椀ltrate… and a challenge that hasn’t gone unnoticed by Angela
Steward, the city’s Associate Director of Sewers and Drainage Planning.
Faced with the increased prospect of combined sewer over昀氀ows (CSOs),
Steward says the city has gone through a “change management exercise
of dealing with how things were done in the past and shifting to a new
way of looking at rainwater,” tied to the Healthy Waters Plan.
Building on the city’s highly successful Rain City Strategy that
involved investing tens of millions of dollars into above ground green
infrastructure to help curb rainwater runo昀昀 and promote urban cooling,
Healthy Waters takes a more holistic grey/green approach. With an
aggressive, $665 million budget over four years, the primary focus of this new
program is to help mitigate CSOs and as its name suggests, reduce water pollution.
On that basis, the city’s new approach when dealing with 昀氀ood prone neighbourhoods where existing sewer infrastructure is no longer adequate is “instead of
committing to upsize those pipes, we’re using rainways to capture enough water,”
shares Steward. And consequently, “we don’t actually have to replace that pipe (and)
we can use that piece of infrastructure for its lifespan instead of prematurely digging
it up and making it bigger.”
Examples she cites includes “what we call a blue-green system along a roadway,
such as a series of bioswales and rain gardens that capture the water and convey it
and it looks really great when it’s raining.”
As part of ongoing e昀昀orts to reduce CSOs, she says there are two ways they’re
looking at nature-based systems; the 昀椀rst being a standard design with some road
improvements and installing green rainwater infrastructure.
With that 昀椀rst approach, they’re then taking the additional step of analyzing
“what those typical designs do for us in terms of how much it reduces the peak
昀氀ows going to our system so that we can then kind of then take that into account.
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