Winnipeg’s ongoing wastewater treatment woes led to the discharge of 1.6 billion litres of partially treated sewage into the Red River in one incident last month.
The previously undisclosed discharge, which left the North End sewage treatment plant between April 21 and 25, was almost 20 times the size of the 78 million litres of diluted sewage released into the Assiniboine River in March, and is the equivalent of 650 Olympic-sized swimming pools.
Chris Carroll, the city’s manager of wastewater services, blamed the situation on that weekend’s torrential rain.
"I’ve never seen these kinds of flows coming in," he said. "We measured 20 year-high flows to the plants April 23 to 25."
The plant exceeded capacity, he said.
The facility automatically diverted some wastewater to bypass some steps of the treatment process, then blend back in with fully treated effluent to leave the plant.
"Everything has a capacity: a bathtub, a bridge can only handle so much weight," he said. "Sewage facilities are the same. They have a capacity that they are designed to treat to and once you hit that capacity, you have to go around it or you risk damaging it."
The city did not provide exact data on the extent of treatment the 1.6 billion litres received, but Carroll estimated the sewage that hadn’t been fully treated would have gone through 30 to 60 per cent of the process.
“Everything has a capacity: a bathtub, a bridge can only handle so much weight. Sewage facilities are the same. They have a capacity that they are designed to treat to and once you hit that capacity, you have to go around it or you risk damaging it.” — Chris Carroll, Winnipeg's manager of wastewater services
The situation differs from a sewage spill, since it is linked to the expected operations of the treatment plant, he said.
If some of the flow hadn’t been diverted, the plant could have been flooded, potentially leaving most of Winnipeg without a working sewage plant for an extended period, he said.
"Depending on the extent of the flooding, it’s not inconceivable the facility would not operate for weeks or longer.… In that instance, you are getting no treatment at all," he said.
"Seventy per cent of Winnipeg would not be serviced by a treatment plant at that time.… That would have drastic consequences on the customers (and) on the environment."
Those consequences could include sewage backup into basements, he said.
Older areas of the city are serviced by combined sewers that collect precipitation and wastewater in a single pipe. The problem occurs when that system is overwhelmed by heavy rain or snow runoff and there are overflows into the rivers. But unlike those overflows, April’s partially treated discharge isn’t subject to immediate public reports, Carroll said. It is noted in monthly reports to the province.
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City officials could not provide data comparing April’s discharge to previous similar events.
The incident is, once again, raising concerns about health risks and environmental damage.
A local water-protection activist said even diluted and partially treated sewage can contain high levels of E.coli and fecal coliform that can make people quite sick, along with high phosphorus levels that promote algae growth on Lake Winnipeg.
"We need to address this urgently…. This is a failure of our wastewater treatment system in Winnipeg," said Alexis Kanu, an environmental scientist and executive director of the Lake Winnipeg Foundation.
Kanu noted $1.85 billion in long-delayed upgrades to the 85-year-old North End treatment plant would increase capacity. However, she said governments have been far too slow to get that work done.
"We needed to have urgency on this 20 years ago, because we’re already hitting our capacity limits and now the latest projection… on upgrading (capacity limits) is 10 years from now. We can’t go through 10 more years of springs like this," she said.
The massive April discharge followed two other significant spring spills into Winnipeg’s rivers. Approximately 60 million litres of diluted and untreated sewage was dumped into the Red about a month after a construction-related spill poured an estimated 78 million litres of untreated wastewater into the Assiniboine.
The problems must be addressed, Kanu said.
"(After) a spill like this (with) only partially treated wastewater, or a spill like the one (in late April), which was untreated sewage, I think we need to say, ‘No, this is unacceptable at any level,’" she said.
"We live in a city where the official line is, ‘Don’t touch the river water.’ That’s just embarrassing.… It shouldn’t be that way."
A Manitoba Indigenous organization added its concerned voice to the conversation Wednesday.
"Our citizens have expressed concern about the impacts of vast amounts of raw sewage making its way from the City of Winnipeg into Lake Winnipeg and into the north basin and the Nelson River," Grand Chief Garrison Settee of the Manitoba Keewatinowi Okimakanak said in a statement Wednesday.
The spills cause environmental and health concerns for those living downstream, he said, urging the province and city to review the impact of the problem.
Born and raised in Winnipeg, Joyanne loves to tell the stories of this city, especially when politics is involved. Joyanne became the city hall reporter for the Winnipeg Free Press in early 2020.