The sponges parks are good. But a sponge city would be better. Water infrastructure specialists estimate that to reduce the number of floods, Montreal will have to go further than moving draining parks and streets capable of absorbing rainwater. In their eyes, the metropolis must now start a 180 degree turn in terms of water management.
What is wrong with the sewer network?
It is not so much infrastructure as logic, which does not hold, according to Scott McKay, specialist in water and environmental sciences. “In town, we have always got rid of wastewater by sending them as far as possible, as quickly as possible. But with climate change, which increases the frequency and intensity of rains, we can no longer think like that “, summarizes this ex-head of the Green Party of Quebec from 2006 to 2008 and former deputy of the Parti Québécois from 2008 to 2014.” We cannot think of being able to harvest all this water and get rid of it as we have done in the past “, adds the one that signed a book sewers, The adventure of the poopin 2020.
How to attack the problem?
By changing our ways of doing things now, said Mr. McKay. “What the city does with the sponges parks is a good start, but you have to go beyond that. Montreal must become a sponge city, ”he says. “It means stopping mineralizing surfaces. I remain in Ahuntsic and I still see people who quipped large parts of their land. It’s so many places that cannot capture water, ”says the expert. According to him, there are many examples of immediate measures. “The sidewalk protrusions must all be draining, then you have to use the parking lots, the large roofs of the buildings to recover the waters. Even the alleys, which represent a lot of space, it would be necessary as soon as possible to tear off the asphalt, break the concrete and fill it with greenery, ”adds the old elected official.
Photo Édouard Desroches, Archives La Presse
Pierre-Dansereau park in Outremont, is a sponge park including a “river” that fills up during heavy rains.
How is a “sponge city” built?
By many small gestures, says Sophie Duchesne, researcher at the Earth Earth Earth Center of the National Institute of Scientific Research. “The citizen, for example, if he has a sloping roof with a gutter, he can direct it towards a permeable surface like grass, rather than asphalt. We should also stop building garages in a sloping basement, but in the meantime, we must multiply the waterproof doors or the bumps which redirect water to the street, ”she notes. More global, adds the expert, “we must also reprofile the streets and redevelop our neighborhoods to send water surpluses somewhere where it does not bother everyday life. It can certainly be a sponge park, but also all the less used sectors in rainy weather ”.
How long can such a transition take?
Establishing a schedule is difficult, since it depends on political will, but it will certainly take decades, says Mr.me DUCHESNE. In the meantime, “we can encourage things like a tax for impermeability in the city”, according to her. “People have to understand what it is for, that we have social acceptability, but that means that a field owner with a large asphalt and concrete courtyard would pay more than someone who has only green facilities. We do not have the choice to go to that, with the extreme events that intensify, ”says the researcher. The important thing, in his eyes, will be to “prioritize interventions without disturbing the traffic and daily life of people”. “You have to support citizens in there, then make sure that the private environment actively participates. »»
Photo Marco Campanozzi, Archives La Presse
Demineralizing the alleys is one of the changes that promote the infiltration of rainwater in the ground.
Are there comparables in the world?
Absolutely, says Scott McKay, who quotes the case of New York. “They targeted a sector around the port where there was a very common overflow problem of the sewer network. And by fittings, they managed to reduce the flows, ”he notes. According to him, the long -term solution is not simply to build larger sewers. “It will not be viable. We already have an infrastructure maintenance deficit in Quebec which is in the order of billions of dollars. We are already not able to maintain the network as it is, so it would be color to think that he can take all the torrential rains in the coming years. We have no choice, politically, to change the city, ”concludes Mr. McKay.
