Swimming in sewage: Ottawa River’s wastewater problem
Ottawa Riverkeeper is monitoring actions that the city of Ottawa and the City of Gatineau are putting in place to manage and control sewage overflows into the Ottawa River.
In their October report, “Brewery Creek and Beyond: The Problem with Combined Sewer Overflows in Ottawa and Gatineau,” the local charity examined five years of water quality data collected at Brewery Creek in Gatineau.
Using the results of the study, they hope to press for positive change for the Ottawa River by continuing to make improvements to sewer systems.
Flushing out combined sewers
During heavy rainstorms or spring snowmelt, untreated sewage often flows directly into the river from combined sewers. This is because of the networks of combined sewers in Ottawa and Gatineau.
Combined sewers collect wastewater and stormwater in one pipe and transfer it to the wastewater treatment facility. But when there is more water than the pipes can handle, for example during heavy rains, the combined wastewater and sewage overflows straight into the Ottawa River.
Emma Konrad of the Ottawa Riverkeeper says this is a threat to both our health and the environment.
“Not only are we talking human excrements, but we are also talking anything that people flush down the toilets, so tampons or prescription medicine, really anything that would have been filtered out at the water station gets bypassed and goes right into the river,” says Konrad.
The wastewater also contains nutrients such as ammonia, nitrogen and phosphorus, all of which promote plant growth and, in turn, deplete oxygen levels for the aquatic organisms in our ecosystems.
There are currently 102km of combined sewers still in Ottawa, as well as 18 combined sewer outlets where untreated wastewater and stormwater can overflow into the environment.
Scott Laberge, the city’s program manager of wastewater collection, says the system was designed to protect older areas of the city.
“During heavy rainstorms, once pipes are full, some of the rain and wastewater mixture is diverted as overflow into the river in order to prevent flooding and sewer backups into homes or businesses,” said Laberge in an email.
According to the Ottawa Riverkeeper report, there were 28 combined sewer overflows from the Ottawa side of the river in all of 2016, releasing about 540 million litres of untreated waste and storm water into the river.
This is equivalent to the amount of water in approximately 217 Olympic swimming pools.
Six of these overflows happened in July and five in August, when recreational use of the Ottawa River is at its peak.
As of early September, there have been 33 events in 2017, which released a total of 1,460 million litres of untreated waste and stormwater into the river.
Although Gatineau does not publicly report their overflows, Ottawa Riverkeeper submitted a request for information and were provided with raw data on the number of overflows for 2016 and 2017.
Using the data, it is estimated that there were 1,350 overflows in 2016 and, as of this year, 1,327 overflows.
The record-setting rainfall in the Ottawa area likely contributed to the large number of overflows in both Ottawa and Gatineau in 2017.
Gatineau’s media office says that while Ottawa has a few large overflows measured at the main sewage treatment plant, Gatineau’s many spills are much smaller, in sewers scattered throughout the city.
However, Ottawa Riverkeeper is concerned that the Quebec government does not require Gatineau to alert the public to an overflow.
Since the beginning of May, Ottawa Riverkeeper has been spearheading a letter-writing campaign, encouraging people from Ottawa and Gatineau to ask their mayors for real-time reporting of sewage overflows.
As part of Ottawa Riverkeeper’s ‘We Want to Know’ campaign, more than 3,000 concerned citizens of have written saying they want to know immediately when raw sewage is released into their river.
The City of Ottawa does report sewage overflows but the information is not released for up to 48 hours.
According to Konrad, this defeats the purpose of a warning system.
“There were times when people could have been choosing to swim in the river without knowing there has been a sewage overflow,” says Konrad.
“They were putting their health at risk without even knowing these overflows had occurred.”
Ottawa’s Combined Sewage Storage Tunnel in progress
In 2010, the City of Ottawa approved the Ottawa River Action Plan.
As a major part of the plan, the construction of an underground combined sewage storage tunnel (CSST) is currently underway and is expected to be completed in 2020.
The CSST will help reduce the amount of raw sewage flowing into the river and is expected to cost the city approximately $232 million.
The federal government and the provincial government have agreed to each contribute $62.09 million to the project. The remainder, an estimated $108 million, will come from the City of Ottawa.
“The combined sewage storage tunnel… will greatly reduce the frequency of sewage overflows during storms from entering the Ottawa River, and will help protect the river,” says Laberge.
The tunnel will hold up to 43 million litres of sewer overflow during major rainfalls. Once the rainfall has subsided, this water will then be treated and returned to the Ottawa River.
“This is a huge move for the City of Ottawa,” says Konrad. “We absolutely commend them because it will be an enormous step towards addressing this issue.”
On the other side of the river, the Gatineau media office says it is working to separate the old storm sewers that are combined with sanitary sewers.
“Ultimately, this will have an impact on the quantity and frequency of overruns; at the conclusion of rehabilitation projects, only rainwater is discharged directly into watercourses, sanitary water being conveyed to the treatment plant even in case of rain or heavy melt,” said the media office in an email.
An overflow management plan is currently being prepared and will be presented to Gatineau City Council in 2018.
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