The City of Toronto says it has begun construction of a new storm sewer system to help reduce the risk of basement flooding with the launch of a tunnel boring machine.

The project involves the building of a new storm sewer system in the Fairbank and Silverthorn neighbourhoods. Fairbank is in the area of Dufferin Street and Eglinton Avenue West, while Silverthorn is in the area of Black Creek Drive and Eglinton Avenue West.

"The end goal is to reduce sewers from backing up and to ensure we are protecting basements from flooding...with the frequency of major storm events on the rise and our city continuing to grow projects like this are more important now than before," said Deputy Mayor Jennifer McKelvie in a press conference on Monday.

"Anyone who's experienced basement flooding knows it can result in costly repairs and damage to cherished belongings...it is a terrible experience no one wants to go through," she added.

McKelvie said once the project is completed, the new system will help reduce basement flooding and sewer backups for 12,500 people living in 4,600 homes.

According to the city, the first section of the 270-tonne tunnel boring machine will be lowered Monday into a 40-metre-deep shaft inside Fairbank Memorial Park, located on Dufferin Street south of Eglinton Avenue West.

"There, the tunnel boring machine will begin constructing a three-kilometre long, 4.5-diameter storm sewer," the city said in a news release Monday.

According to the city, the completed project will also help reduce 40 million litres of annual combined sewer overflows into Black Creek and other local waterways.

In 2019, CBC reported that the federal government contributed $73.2 million to the project and the city contributed $133.49 million.

The Fairbank Silverthorn Storm Trunk Sewer System will be completed in 2026.