Q&A: Climate change is directing how the city looks at stormwater
Engineers are planning future infrastructure for the possibility of more intense weather events
As Heavy rain continues to be one of the defining features of summer in London this year, CBC London Morning spoke to an engineer with the city to learn more about how wastewater is managed and how climate change is impacting future infrastructure planning.
Ashley Rammeloo, the director of water, wastewater, and stormwater at the City of London, spoke with guest host Matt Allen about where rainwater goes, and how they're preparing for the future.
The following has been edited for length and clarity.
Matt Allen: So you're the one who's responsible for keeping us dry when heavy rain falls. Where is all that water going?
Ashley Rammeloo: Well, eventually it'll make its way back into the environment, whether that's soaking into the ground or making its way into creeks and/or the river directly. So what we do is we're trying to make sure that water gets there while causing as little impact to the residents as possible, but also protecting the environment.
MA: So are you guys pulling your hair out when you think about things like climate change and increasing amounts of water and precipitation?
AR: It's definitely a concern. The biggest impact we've seen is the intensity of the storms. We'll get a storm where we get a month's worth of rain overnight, and although our infrastructure can take the total volume, it can't move it away as fast as it's coming. That's when you tend to get those streets flooding. It goes away fairly quickly, but there is a time period when it's sitting on the road.
Part of our consideration is how to get that water away quickly enough, but also we have to balance that on the other end because when it goes into those creeks and the river, you have to be managing those flows too so that you don't get a lot of erosion along the banks.
MA: How is infrastructure adjusting to that? How is the design of storm drains or culverts being adjusted over the years?
AR: We design those according to what's called a 'whatever year storm.' So, for instance, the highest-rated storms are the one-in-100-year and the one-in-250-year, like a hurricane. Not all of the sewers underneath the road are sized to those because they would be massive and we can't really construct it realistically from a financial or a space perspective. So we have to look for a middle ground.
When it comes to things that are for flood protection specifically, we're now looking at designing for that 250-year storm, whereas we used to design them for 100-year storms.
WATCH | How climate change is impacting future infrastructure planning in London:
MA: So you're having to plan for even more extreme events more often now?
AR: We do, yeah. Also, with those higher-intensity rainfalls, we're looking at ways we can actually infiltrate water more in the areas where it falls. For example, LIDs, or low-impact developments, like rain gardens that people can put in on their property to help absorb some of that water so it doesn't run off and cause so much flooding.
MA: What are some of the things that homeowners can do to prepare for these extreme events?
AR: So if you have a sump pump, if you have a backwater valve, make sure those are functioning. Always make sure your downspouts are pointed well away from your foundation.
Longer term, if you're doing projects in the yard or you're changing the grade of your yard, make sure you're still keeping that water flowing away from the house, and that you're not flooding out yourself or a neighbour.
If you have a home built prior to 1985, make sure your weeping tiles have been disconnected from the sanitary sewer. We used to allow those foundation drains to drain the stormwater and it would then overwhelm the sanitary sewer and then you get sanitary sewage backup into your basement as a result of the large rain. It's nasty. You don't wanna deal with it.
LISTEN | Ashley Rameloo on CBC London Morning on stormwater and city infrastructure: