Sewage floods waterways
More than a billion litres of sewage discharged into Niagara waterways last month
Niagara’s sewage treatment plants spilled more than one billion litres of diluted sewage into area waterways in the past month, as record rainfalls inundated the Region’s infrastructure.
The excessive rain this spring has forced Niagara Region to discharge a total of 1,094 megalitres (1.094 billion litres) of sewage during 35 sewage bypasses at Niagara’s wastewater treatment plants in May, said Jason Oatley, acting associate director of wastewater operations and laboratory services.
That’s more than 10 times the usual levels for the month, and about half the amount of sewage discharged during an entire typically rainy year.
“We’re way out of the normal. In a wet year, we may have had 14 days for the entire year … It’s been very different than usual,” Oatley said.
Sewage bypasses occur when large amounts of rainfall infiltrate the sewer system through combined sanitary and storm sewers in communities throughout Niagara.
And Niagara has had plenty of rain in the past month.
Oatley provided a Niagara Region report showing an average of 148.7 millimetres of rain fell on Niagara in May, compared to 21.23 mm in May 2016 and 68.50 mm in May 2015.
“It’s been very atypical I would say, just from the number of days of continuous rainfall that we had in May.”
Oakley said sewage bypasses sometimes occur in March and April due to heavy rainfalls and melting snow, but this year “almost all of it has fallen in May, in a very compressed time as well.”
Normally, the ground absorbs a lot of moisture, minimizing the impact on sewer systems. But this year, the ground was already too saturated to allow that to happen.
“The extra wet weather saturates the ground around the sewer pipes and can infiltrate the sewer system,” he said, adding downspouts and foundation drains that are tied into sanitary sewers also contributed to the excessive sewage flows wastewater treatment plants experienced during the month.
The Region has wastewater storage capacity for hundreds of millions of litres, designed to prevent overflows from occurring. But not enough to contend with the deluges that occurred during the past month.
Sewage entering Niagara’s wastewater treatment plants normally goes through several processes, including primary treatment which removes heavy solids and oily substances, secondary treatment that removes dissolved organic material and nutrients such as ammonia and phosphorus, and final treatment processes that remove solids. From there the fully treated sewage is disinfected and discharged.
But during the 35 bypasses that occurred in May, untreated sewage was discharged 14 times while sewage that received only primary treatment was discharged 21 times.
Oatley said even sewage that is considered untreated has had chlorine added and objects such as rags, sticks, trash, rocks and grit screened out.
“If it doesn’t get full treatment, it still gets disinfected to remove bacteria and things like that,” he said.
It’s also highly diluted by the time it’s discharged.
“Please keep in mind that when the flows are that high, the actual amount of sewage in the flow is lower since there is so much rainwater mixed in it,” Oatley said.
Although it’s still considered sewage, he said “it’s not the same sewage that we’d bypass if we didn’t have a treatment plant and just let everything go out into the lake.”
Most of the bypassed sewage — 302.44 megalitres — came from the Niagara Falls treatment plant, followed by 280.8 megalitres in Port Weller, 260.12 megalitres at the Welland plant, and 129.98 megalitres in Port Dalhousie. Queenston wastewater treatment plant: 0 Stevensville: 0 Crystal Beach: 0.84 Seaway: 42.06 Anger Avenue: 36.73 Baker Road: 41.15 Port Weller 280.8 Port Dalhousie: 129.98 Welland: 260.12 Niagara Falls: 302.44
All sewage bypasses are reported to the Ministry of Environment.
The excessive rain has contributed to elevated E. coli levels in Niagara waterways, said Anthony Habjan, an environmental health manager for Niagara Region’s health department.
Warnings have been posted at seven Niagara beaches due to high levels of E. coli, including Crescent and Waverly beaches in Fort Erie, Nelles Beach in Grimsby, Charles Daley Park east and west beaches in Lincoln, Lakeside Park beach in St. Catharines and Belleview Beach in Wainfleet.
When water samples taken at five locations on the same beach show E. coli levels in excess of 100 parts per million, warnings are posted.
Habjan said the health department monitors sewage bypasses to determine if they are occurring at treatment plants near public beaches.
Although the sewage could be contributing to the problem, he said it’s secondary to the impact the excessive rainfall and recordhigh lake levels are having on water quality.
“That would be the majority of the issue,” he said. “Because for example at Lakeside Park, (the water) was almost in the parking lot. What happens is, you have to think of all of the dirt and debris and animal feces — all of that is being drawn into the water. You can see the murkiness of it and the turbidity.”
Habjan said rainwater running off the land also causes elevated levels of E. coli for at least 24 to 48 hours.
“You take all the rain, plus the high water levels. That’s probably the main factor on why those beaches are being posted,” he said.
Albert Garofalo, a botanist and environmentalist working with the Bert Miller Nature Club, fears the additional bacteria due to the rainfall and sewage bypasses will contribute to larger algae blooms particularly on Lake Erie, when the hot temperatures arrive later in the summer.
“It will exasperate the problem, and already it was pretty bad,” he said. “No doubt it will be worse this year.”
It also demonstrates the importance of sewer separation projects, to prevent the flow of rainwater into sanitary sewers.
“It’s absolutely essential,” Garofalo said.
Meanwhile, Oatley said the extremely high water levels in Lake Ontario in particular have aggravated problems for wastewater treatment plants.
“At one station in Niagara-onthe-Lake, we’ve been fighting the river itself that wants to come into the storm sewer,” he said.
Normally, that station would overflow into the Niagara River, “but it can’t overflow because the water levels are so high.”
“It’s meant we’ve had to do a lot of bypass pumping at that location, which is very unusual for us,” he said.