It sounds like one of those cheesy kid jokes. Name the tunnel deep under Ottawa’s downtown core that is longer than the LRT but no one really knows about?   

“We get confused with the LRT all the time,” laughs one of the project managers Steve Courtland.

“It’s the big project that’s right in front of everybody but nobody really knows what’s going on.”

Courtland’s colleague and co-manager of the project, Jenn Carreirra says the tunnel, under construction for the last three years, is equally as important as the LRT and has a very lofty goal. 

“It’ means a healthier river,” says Carreirra.

The pair is heading up the city of Ottawa’s Combined Sewage Storage Tunnel (CSST) project.  It’s a $232 million state-of-the-art sewage tunnel network, eight storeys underground, with the aim of stopping sewage spills into the Ottawa River.

“The goal really is to reduce our combined sewer overflows to the river,” says Carreira.

When heavy rains hit the capital, it can put a lot of pressure on the city’s current aging sewer system.

“Showers, sinks, laundry all of that goes into the same pipe as rainfall,” says Courtland,

“So when we have a very large rainfall event that system gets overwhelmed.”

It means that the massive amounts of dirty, stinky water have nowhere else to go but into homeowner basements or the Ottawa River.  Each swimming season the city of Ottawa estimates an average 25 of those sewer overflows into the Ottawa River.  The goal of the CSST network is to bring those overflows down to one.

“We’ll be putting cleaner water back into the river for sure,” adds Courtland.

The underground CSST is a total of 6.2-kilometres long and runs from Lebreton Flats to New Edinburgh Park and from Kent Street to Chamberlain Avenue.  Carreira says it won’t just help keep the river clean but will keep basements dry as well,

“That tunnel will help solve a historic flooding problem in the Centretown area and the north end of the Glebe, something that could affect about 7,000 residents.”

The CSST will work by acting more like a large holding tank, equivalent to 18 Olympic-sized swimming pools, the tunnels will hold on to the water until the treatment system is freed up.  Once the system is ready, that sewage will then get treated and cleaned as well before heading back out into the river.

“The project has an aim of protecting our precious Ottawa River,” says Carreira.

The CSST is about 85-percent complete, with a rollout date of fall 2020.