Floods: sewers may not be the answer
CBC asks what the city can do to mitigate flood damage and finds an expert who makes a case for sewers not being the answer.
An SPVM officer is said to have saved the life of an 80-year-old driver whose vehicle got stuck under an overpass during Sunday’s downpour.
Ephraim 19:56 on 2025-07-16 Permalink
In some countries they are using asphalt with no sand, so it’s porous. Others, like Germany are going back to using bricks on the roads, not only does it allow water to go through, but you don’t have to repave everything to fix it. You just pull out a few blocks and put in a few blocks. Costs more initially.
Nicholas 20:48 on 2025-07-16 Permalink
Ephraim, I’ve been told bricks here are just way more expensive because of our trucks. Over there you can have a few layers of soil/sand/crushed stone underneath and then lay bricks on, very cheap. As you say it’s easy to repair infrastructure underneath. The problem is heavy trucks. There they don’t have as many heavy trucks, or as heavy trucks, or those are limited to highways and industrial access roads. So they only put brick on local streets, where you can bring a box truck but not a 53′ one (tractor trailer/semi/big rig/18 wheeler). Here in North America it’s every truck’s god given right to go anywhere, and even if they’re banned from local streets they’re still allowed for deliveries (there you have to transfer everything into box trucks). And that is too heavy for the subsurface, so it sags and sinks, and it gets bumpy super fast. So here you have to put in a concrete base under the brick, defeating the cheap infrastructure repair benefit, and raising the cost significantly. You need to absolutely ban those large trucks for all purposes, no matter what, MEME POUR LIVRAISON/DEMENAGEMENT and fine them massively if they break the rules. And people just aren’t willing to do that. Maybe for alleys, that’s our best bet, and some pedestrian streets with alleys.
mare 23:24 on 2025-07-16 Permalink
@Nicolas I agree with you. Snow removal should also be done with cargo bikes and not those big ass semis. /s
Snow and ice are a big issue for brick streets. If bricks aren’t cemented in here they won’t survive many winters because of the violence unleashed upon them by snow plows and snow scrapers and also frost heaving (a virtually unknown phenomenon in Europe). It’s a whole street of potholes, ready to be released one by one.
DeWolf 00:56 on 2025-07-17 Permalink
Unfortunately the answer to many questions about why we can’t have certain nice things in public space here is snow clearance. It’s an incredibly brutal process. Even granite curbs and other stone surfaces are heavily damaged after just a few years when they’d last relatively unscathed for decades in other places.
I’m convinced there is a way to reform snow clearance so that it isn’t so destructive and wasteful (and expensive), but it would require a real paradigm shift in how we manage our public spaces.
DeWolf 01:01 on 2025-07-17 Permalink
But to expand on my thought, there’s still a lot of low-hanging fruit even without changing the way we deal with snow. There is no snow removal in most alleys so there’s no reason they should be paved in asphalt. My alley is an absolute sea of asphalt even though technically it is a ruelle verte (thanks to some very vocal residents who were militantly opposed to more greenery, for reasons I can’t fathom).
Jonathan 09:23 on 2025-07-17 Permalink
I just don’t understand why they still allow the draining from flat roofs to go directly in the sewer. There should be updated building and municipal codes that require the roofs be disconnected and funneled into permeable surface. Most boroughs already require a certain percentage of a lot be permeable, so these areas that can take water already exist in theory.
When you imagine every rain drop that falls on a road or a roof goes into a drain which then passes through the treatment plant in the east end… It’s just a crazy amount of water and no sewage system can handle it ever. That’s what giant rivers like the st Lawrence River can only handle.
Kevin 10:58 on 2025-07-17 Permalink
@DeWolf
Do they have garages or parking in their backyards? My back alley is mostly unpaved, but at my end it’s paved because 6 houses have back alley driveways and garages, and for some places (like mine) the only way to access the furnace room or install a hot water tank is through the back alley.
@Jonathan
That may theoretically be possible for new construction, but it’s not even remotely possible for existing homes.
I have a flat roof and I can’t even conceive of how I’d divert the roof drain – which is in the centre of my building and ties into the main stack – to an outside wall for less than $100,000. I’d have to rip out a wall or two, jackhammer through a chimney-like-structure, then run a drain pipe under a floor and since going through 15 or 20 joists would be structurally unsound, lower the ceiling for several rooms by about 30 cms.
That’s never ever going to happen.
DeWolf 11:19 on 2025-07-17 Permalink
@Kevin Yes, but this wasn’t a plan to close the alley to cars, or to completely de-pave it. Just to add some trees and other greenery along the sides. The comité managed to do that along most of the alley and in those sections, it’s still wide enough to accommodate not just cars but even giant construction vehicles. It’s just that there was a group of residents who were militantly opposed to any sort of intervention whatsoever. Not coincidentally, the same people have hard-paved backyards with (at most) a few ornamental shrubs, and they make a point of dousing the sidewalks in herbicide every summer so there are absolutely no weeks poking up through the cracks. It’s ideological more than anything else.
Chris 15:21 on 2025-07-17 Permalink
My roof is also flat, and the pipe goes down the centre of the home to the basement. The building has neighbours attached on two sides. To make the pipe go outside, and be only gravity powered, would be a crazy impossible/expensive reno.
One possibility though would be to store such water in a tank in the basement and use it as grey water to flush toilets, or release to the sewer system slowly, on dry days.
Andrew 16:16 on 2025-07-17 Permalink
It doesn’t apply to individual homes, but bigger buildings have flow limiters where their drain connects to the city storm drain. So if you have a crazy rainfall over 5 minutes, they retain water on the roof or in the parking lot that drains slower over a long period to avoid overwhelming the system.
Jonathan 19:58 on 2025-07-17 Permalink
Re: my comment on the flat roof drain, I have a flat roof and recently replaced it, including the trusses and all. The roof originally had a space of 3’9″. The new roof design, with a less dramatic slope allowed the new roof space to only be 2’10”. I think a diverted drain pipe with an overflow gasket that drains into the main stack could fit in a space of 11 inches no problem. If there was a subsidy for this, I probably would have considered it and would likely not have increased the overall cost of replacing the roof by a high amount.
Ephraim 21:45 on 2025-07-17 Permalink
Just out of curiosity, Duluth is paved with bricks from St Lawrence to St. Denis. So, there must be a way to do it, no?
Kate 09:54 on 2025-07-18 Permalink
Ephraim, I used to live near Duluth, and the local lore was that the city had paved it with driveway quality pavers, not meant to be driven over heavily. By the time I left the neighbourhood, there were asphalt patches all over the place to replace the broken bricks.
The story may be true, because I’ve also heard that it was initially the plan to make Duluth into a pedestrian passageway all the way from Jeanne‑Mance Park to Lafontaine Park, so they were not expecting it to carry much motor traffic – maybe only delivery vans and emergency vehicles. But as we know, that didn’t happen.
Ian 18:09 on 2025-07-18 Permalink
Last year there was dead squirrel that ended up in one of the potholes on my street, the crows dragged it there for safekeeping after it had been initially picked over. When the city came by to fill potholes thay just filled in the hole with the squirrel in it – which I thought lazy at the time – but perhaps they are experimenting with squirrel-based water absorption.