WC136 MayJune 2024 - Magazine - Page 22
STORMWATER
From science fiction to real world
When she first heard of Rotterdam’s watersquare from Haf and
his team, Mayor Maja Vodanovic of the Montreal borough
Lachine recalls that the concepts behind the water park “seemed
like science fiction,” vis-à-vis the otherworld idea of creating
public space that could also be used to divert heavy rainfall.
Deciding to make what seemed surreal real, “slowly we started
adopting” the installation of these new water catchment projects,
Vodanovic said, who in addition to her mayoral duties helps oversee Montreal’s water infrastructure initiatives. Fast forward to today
“and now we’re accelerating the process,” she added. “And (Haf )
has become like the superhero that started the whole process.”
Montreal’s recognition as one of the “spongiest” cities in the
world by Arup is attributable to the fact that in recent years it has
created seven sponge parks and 800 highly permeable sidewalk
installations. And looking ahead, one could argue that its fourthplace ranking will only get better thanks to plans to build another 30 parks and 400 more sponge sidewalk projects by 2025.
Projects critical to the city’s efforts to become more resilient in
the face of more frequent heavy rainfall events. Including the July
13, 2023, storm when some areas were hit with 100 millimetres
of rain within the span of a couple of hours, causing traffic chaos,
road closures and knocking out power for hundreds of thousands
of residents both in Montreal and other parts of the province.
Because of climate change and extreme weather events such as
the one last summer, Montreal, not unlike other cities around the
world, is planning for more frequent 100-year storms. And part
of their response is to build more water catchment installations
in flood prone parts of the city.
Vodanovich said six of their most recent parks have the capacity to store two million litres (2,000 cubic metres of water) “and
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WATER C AN ADA • M AY/JUNE 2024
the two (parks) we are building this year are
(both) going to be 2,500 (cubic metres).” There
are another 20 parks planned for construction
in the future that will absorb a combined
13,500 cubic metres.
The city has also studied just how effective
these parks are in terms of being able to quickly
absorb large volumes of water. One such study
was conducted with a bioretention pond in
Place des Fleur Macadam in Le Plateau.
Built on the site of a former gas station,
“the soil there was contaminated, so we had
to remove it and put in sand, which is very
good for infiltration,” Sophie Bérard, an urban
infrastructure design engineer with the city
who helped to oversee this work, said. As for
the outcome of the test, “we actually opened
the (nearby) fire hydrant and the bioretention
pond was able to infiltrate the (equivalent of a)
100-year rainstorm.”To funnel rainfall more effectively into these parks, “we are trying to redo
the slope of most of the streets directly around
the parks (and) we also have catch basins that
bring water into these parks,” Bérard added.
In the multipurpose spirit of Dutch projects,
these special parks include everything from
fountains and grassy areas where kids can
play, to picnic tables for sitting and eating, with basketball courts
among the amenities on the city’s radar for future sites.
As for their sidewalks, Vodanovich said the city has evolved from
just wanting to beautify them by bordering them with plants and
gardens to narrowing the road and using the additional space to accommodate more plantings, then redirecting water from the roads,
which in turns supports the vegetation. In the spirit of a multi-purpose park, at the same time they’re beautifying their sidewalks,
they’re also transforming them into draining infrastructure.
Coping with the Unlucky 13
Just as one of Montreal’s biggest storms landed on the number 13
(July 13), Calgary has also been slammed by disasters coinciding
with that unlucky number. In their case it was the flood of 2013,
which was the city’s largest since 1897, causing the loss of one life
and an estimated $6 billion in damages.
Calgary’s chaos in June of that year came about as a result of
heavy rainfall on the melting snowpack, causing rapid flooding
of the Bow River, which bisects the city, peaking at 2,400 cubic
metres of water per second, or eight times its normal flow.
The impact in terms of numbers included: the evacuation of
110,000 residents in 26 neighbourhoods; 20 bridge closures; the
cancellation of 50 bus routes; and 34,000 homes losing power.
It was a storm that amplified Calgary’s strengths and weaknesses. A city close to the great outdoors (just a 1.5-hour drive to
WAT E R C A N A D A . N E T
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urban environment with a water management system to bring
(the watersquare) into the cityscape,” van Peijpe said. That in contrast to much less creative, single department dominated technical
solutions used in the past for solving local flooding issues.
For the departments involved, “it was completely unknown
territory (including having) a sewage expert participate in (the
planning of ) a public space project,” van Peijpe recalled. And in
light of established department divides, “it took a lot of time to
link budgets together… for other purposes than what they would
normally do.”
Not surprising, there was pushback from various departments
as well as members of the general public they had to answer to as
well. “When you do something that has never been done before,
yes, you get questions about such things as public health… or
whether people might drown (when the square fills up with
water). So, all the problems were put at the table,” he said.
But ultimately those silos came down, the objections receded,
and the water park came to fruition, inspiring the construction
of similar projects in cities around the world, including, of
course, Montreal.
