How much sewage is going into the Thames? A city website could soon answer that question

London, Ont. residents and downstream communities may soon be able to see in near real-time when wastewater is being dumped into the Thames River during high rainfall events.

Untreated and treated wastewater going into the river has been an issue in London and other cities for decades thanks to outdated infrastructure where sewage, including what's flushed down toilets, flows through the same piping as stormwater collected from street storm drains.

During heavy rainfall events, the combination piping can become overwhelmed, forcing an overflow, where all of it — sewage and stormwater — is diverted untreated into the river to prevent residential basements and streets from becoming flooded by wastewater.

The city tries to get as much overflow as possible to pass through its wastewater treatment system, but bypasses — when partially-treated wastewater is released — can occur in order to prevent permanent equipment damage.

The city says there are plans for a website that will make it easier for the public to access and make use of data collected during such overflow and bypass events. It's hoped the website will be online early next year.

"[It] just provides that extra level of visibility. Currently, we do monitor these things, but the notification process can actually occur well after the actual event," said Kirby Oudekerk, London's division manager of wastewater treatment operations.

"It's felt that being able to provide real-time notification gives people more information to make informed decisions about what they're doing and how they're interacting with the environment."

Roughly 12 kilometres of combined piping remains in the city, or about eight per cent of London's overall sanitary sewer network, a number that shrinks every year. Oudekerk notes, however, that even with separate piping, stormwater still finds a way into the system.

Nearly 141,100 cubic metres, or roughly 141,100,000 litres, of raw, untreated overflow has been released into the Thames River so far this year. Of that, nearly 42,000m³ were released over a 45-hour period on March 31 when the city was inundated with rain.

Overflow and bypass data is already available on the city's website, but only after the fact and in the form of a spreadsheet. Oudekerk says the planned website would allow users to see the data in near real-time, with a map showing the locations where they're happening.

On Tuesday, the Civic Works Committee voted in favour of a single-source procurement, providing roughly $60,000 to Blue Siren Inc. to implement and host an online overflow monitoring and notification system. The vote goes before full council later this month.

The city's existing sewer monitoring equipment is from Blue Siren, and the city will be reimbursed by the province through a grant program that expires in March. 

The intent is to purchase enough equipment to complement the existing monitoring system, and potentially extend the system to additional locations, according to a city staff report.

Among those who would benefit from such a website are communities downstream, including Oneida Nation of the Thames.

The First Nation, located southwest of London, sources its drinking water from an aquifer under the Thames using a GUDI system, or groundwater under the direct influence of surface water. 

The community has been under a long-term drinking water advisory since September 2019, while the neighbouring Chippewas of the Thames First Nation has had an advisory in place since December 2021.

"I think this is a really good step forward for the City of London, and many of the downstream users of the Thames River," said Brandon Doxtator, an Oneida councillor and its former environmental co-ordinator.

"For quite a while, the City of London was not releasing that information, and we had to push them on that."

Work is underway to hook up Oneida to the Lake Huron Primary Water Supply System, which supplies water to London and other non-Indigenous communities. Construction on the connection is set to get underway in the spring of 2024.

"There is a lot of perceived risk… A lot of them don't drink the water still, through their taps. A lot of them are using bottled water, basically for all necessities right now, for cooking, for brushing teeth," Doxtator said of Oneida residents.

He added he was hopeful the city would use the opportunity to "engage with all downstream users of the Thames River," and use the data to better understand the impacts of overflows.