The 48-hour rule all beachgoers must know about sewage

Wednesday, July 5, 2017, 3:34 PM - As a result of the recent record-breaking rainfall in southern Ontario, Toronto officials dumped over 1.3 million cubic metres of partially treated sewage into Lake Ontario in May.

Krystyn Tully, a co-founder at Lake Ontario Waterkeeper, has been trying for years to bring sewage bypass alerts to the people of Toronto. While the city notifies the Ministry of Environment every time a wastewater treatment plant bypass occurs, there was a time the alerts were never made public.

However, all this changed in June, when the city started to send out public notifications via Twitter.

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"Reporting when bypasses occur should be automatic anywhere that it's happening, so all across Ontario and Canada," Tully told The Weather Network. "The City of Toronto absolutely should be doing it because we have more frequent overflows here than any other city in Ontario."

According to a Tweet published by Toronto's 311 Contact Centre, the last bypass at the Humber Wastewater Treatment Plant took place on June 30, 2017.

In the Tweet, the centre explains a "bypass occurs when heavy rain causes the volume of combined rainwater and sewage reaching a plant to exceed what can be treated and processed."

During heavy rain events the increased amount of rainwater and sewage can be fully treated for a period of time. However, if the rain continues some of the wastewater can be diverted through what is known as a bypass.

In total, there are four wastewater treatment plants in Toronto, but only two perform bypasses: Ashbridges Bay and Humber.

Humber conducted three sewage bypasses in the month of May, one of which that released over 512,000 cubic metres of partially treated sewage. The entire process took 32.5 hours to complete.

According to Tully, a bypass rarely lasts for more than 24 hours.

"As the city gets bigger, our infrastructure gets older and wet weather comes more often, this is going to happen more and more frequently," she said. "We need to make sure we are investing in the right infrastructure at the right scale, so that we can outpace the impacts of climate change."

Every time it rains, a Lake Ontario Waterkeeper contacts each plant to ask if there has been a bypass and when the last one occurred to ensure there are no gaps in their records.

Tully hopes that with the new social media alerting program in place they will no longer have to contact the plants to seek information. Instead, the public will get the alert directly from the city.

Know the 48-Hour Rule

In any event, Tully recommends residents wait 48 hours after it rains to go into the lake. Those at greater risk, including children, elderly or people with compromised immune systems, should wait a bit longer.

"Bacteria which is the main indicator of sewage pollution only lives in the natural environment typically for 48 to 72 hours, so you're waiting for that bacteria to die before going back into the water," Tully said.

"There is always a concern that there are things like viruses that live for a lot longer than bacteria, so it doesn't mean it's going to be exactly clean after 48 hours, but it means that the risk of contracting a water-borne illness drops significantly."

What occurs in a bypass?

According to the city of Toronto, all wastewater released from Toronto's wastewater treatment plants operate as per strict provincial and federal regulatory requirements.

What occurs in a bypass is dependent on the age and capacity of the plant. In the case of a severe rainstorm in Toronto, some of the incoming flow to the wastewater treatment plant is diverted around what is known as the aeration system (where oxygen is added) and rejoins the rest of the flow prior to the disinfection process.

Due to bypassing the aeration process during storm events, the liquid is mostly rain water, which is often times comprised of a ratio of four or five parts rain to one part sewage, according to the city.

The storm-related flow eventually joins the fully treated flow, and then both are disinfected.

Tully explained there are two concerns when it comes to dumping partially treated sewage into Lake Ontario: human health impact and the effect on aquatic life.

It's not clear that everything that affects human health is being filtered out during a bypass, Tully highlighted.

"So at the very least the people who are surfing or paddling where the bypasses are taking place should be given enough information that they can make a decision for themselves whether they want to be out there or not," she said.

When it comes to aquatic life, animals and plants don't have a choice, Tully added.

"Just because the bacteria may have been treated with chlorine, it doesn't mean the pharmaceuticals and other plastics, metals, oils and greases that can be presented in partially treated sewage are not going to have an impact on quality of water, sediment, birds, or anything that is trying to live out on that lake."

Learning from other cities in Ontario

When it comes to improving water quality and proper treatment of wastewater, Lake Ontario Waterkeeper believes Toronto should take notes from Kingston.

About fifteen years ago Kingston experienced a lot of problems with their sewage collection and treatment, and experts at Lake Ontario Waterkeeper were very critical of the city's process, explained Tully.

The water charity brought a legal application challenging the city's licenses in 2005, noting that they needed to start reporting to the public and cleaning up after spill events. The sewage treatment upgrade as well as the combined sewer replacements have been happening since then, with improvements accelerating in recent years, according to Tully.

"Kingston realized that a lot of its sewage pollution was affecting nearby municipalities like Wolfe Island, and so they needed to do a better job sharing what they knew with other people," she said. "As a result they have gone from the worst to by the time they are done their upgrades, one of the best municipalities in the province, if not the country when it comes to capturing, monitoring and reporting."

Tully believes Toronto should adopt a similar overflow map like Kingston's that includes real-time updates.

"Failing that technology, the next best thing would be to more proactively alert the public," she said. "So, a standardized press release that could go out to the media, so the media could help spread the word much like a hot or cold weather advisory."

In order to protect and restore local waterways, including Lake Ontario, Toronto city council has adopted the Wet Weather Flow Master Plan in 2003. This includes controlling debris and pollution that enters Toronto's stormwater system with street sweeping, catch basin cleaning and standard maintenance procedures, according to the city's website.

Officials have also implemented a city-wide mandatory downspout disconnection program, the construction of stormwater ponds and a basement flooding protection program.

"We are trying to build one of the greatest cities and places in the world to live and part of that means having a waterfront that is unparalleled," Tully said. "The city should be looking at how people are using the waterfront and figuring out how to keep them safe and feeling connected to the waterfront, and taking responsibility for the state of our infrastructure and sewage problems is part of that process."

SOURCE: City of Toronto | Ashbridges Bay Wastewater Treatment Plant | Humber Wastewater Treatment Plant