Canada

Tunnelling for Canada’s Largest Outfall Completed

On March 3, 2022, a 7.95 m diameter Robbins Single Shield TBM completed boring at the Ashbridges Bay Outfall Tunnel in Toronto, Ontario. The tunnel boring machine launched in March 2021 from an 85 m deep, 16 m diameter shaft and began its bore in predominantly shale, with limestone, siltstone and sandstone.

Robbins, construction company Southland, and other personnel celebrate the completion of tunnelling at the Ashbridges Bay Outfall Tunnel in early March 2022
Credit/Quelle: Robbins

Robbins, construction company Southland, and other personnel celebrate the completion of tunnelling at the Ashbridges Bay Outfall Tunnel in early March 2022
Credit/Quelle: Robbins

The completed wastewater outfall will connect to the 50 in-lake risers to enable efficient dispersion of treated effluent over a wide area of the lake, making it the largest outfall in the country. The project for the City of Toronto will improve the city’s shoreline and Lake Ontario’s water quality by replacing a 70-year-old existing outfall.

Daily Probe Drilling for Water

“This is a wonderful type of geology for our machines. During the entire excavation, a total of seven cutters were changed. The wear behavior is incredible, between 2 and 5 mm, and everyone is amazed by the cutter performance,” said Alfredo Garrido of Robbins Field Service.  “Every 25 machine cycles, it was necessary to stop the excavation to probe drill hole in front of the cutterhead to check for possible water. This drilling was done basically every day, stopping the machine for a few hours, but it was very necessary,” said Garrido. The last kilometer of tunnel, bored below a series of 50 risers under Lake Ontario, was challenging but ultimately successful.

All-Remote Machine Acceptance

The project won accolades from the Tunnelling Association of Canada (TAC) in late 2021 for its all-remote machine acceptance enacted due to the Covid-19 pandemic. The machine acceptance, the first of its kind, enabled communication and confirmation between the machine’s assembly location in Mexico, suppliers in the U.S. and those involved in Canada.

x

Related articles:

Issue 02/2023

Young Forum of the STUVA Conference: Three Winners Share Exciting Journey in Canada

In the last three years, however, travelling was not the easiest thing to do ... At the STUVA Conference 2019, Dr.-Ing. Ivan Popovic of ZPP Ingenieure received the STUVA Young Talent Award for his...

more
Issue 06/2013 Canada

Niagara Tunnel – providing renewable Power to Ontario for the next 100 Years

In March 2013, after eight years of tireless work, the largest hydroelectric project in Ontario in the past 50 years came to completion to the cheers of hundreds of onlookers. The new 10 km long...

more
Issue 07/2014 Young Forum

2013 Young Scientist Prize – A Trip to Toronto

Within the scope of the 2013 STUVA Conference, Mag. (FH) Susanne Fehleisen, ÖBB Infrastruktur AG, came out on top at the “Young Forum” competition winning the prize for her contribution “Koralm...

more
Issue 07/2016 USA

Veteran TBM is boring 28 km of Wastewater Tunnels in Indianapolis

In early September 2016, one of the longest-running Robbins TBMs embarked on its most extensive project yet. The Main Beam machine with a diameter of 6.2 m, owned by the Shea-Kiewit (S-K) JV, is...

more
Issue 06/2011 Canada

Massive Main Beam Machine Breaks Through at Niagara

May 13, 2011 marked the completion of the world’s largest hard rock TBM drive at Canada’s Niagara Tunnel Project. A well-attended ceremony celebrated the final breakthrough of the 14.4 m diameter...

more