WATCH ABOVE: Spring is here! But where do all the puddles, rocks, salt, rain and debris go? On today’s Off Limits, Michel Boyer takes us down under, where few dare to venture.
Edmonton Off Limits is a special series that takes you behind closed doors to places that are usually forbidden or too dangerous for the general public.
EDMONTON — Once rain water goes into city sewers, few ever think of where it ends up. Does it get mixed in with the rest of our household waste? Does it get recycled back into our drinking water system?
Here in Edmonton, rain water doesn’t take either of those paths.
It goes from the sewers, through a long network of pipes, and eventually ends up in the North Saskatchewan River.
Even before it gets there, the city tries to remove as many solids as possible using a system seldom seen in other cities.
“This is a special chamber,” said Lynn Lebirk, drainage trainer with the City of Edmonton. “We filter heavy metals from the water before they get to the river, so it’s kind of a final stage of filtration.”
The chamber, a dozen feet below ground, is usually full of water flowing in from sewers.
At the bottom the chamber, the plastic filters are covered in mud. But inside there is a special substance called perlite.
“It allows the water to free flow through the filter, trapping in hard metals,” Lebirk said. “Then, the water goes to the river.”
The sewer water, which includes runoff and rain, travels through a completely separate network of pipes than waste that leaves your home’s plumbing system.
Few cities in the world have this type of system. It began as a pilot project in Edmonton.
After every major rain event, crews empty the chambers, go down and switch out all the filters with clean ones. That process can take a week. Meanwhile, a second chamber takes over.
Even though only runoff goes through the chamber, the dangers are still very real. Often, oil, gasoline and other substances end up in the drain system. That can create dangerous gases. The filtration system can’t stop those liquids from ending up in the river.
We would like to thank the City of Edmonton for its help with the Edmonton Off Limits series.
If you have any Off Limits story ideas for our next series, please email us at edmontonofflimits@globalnews.ca.
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