Tunnel boring to Toronto Island far from boring, says contractor

Tunnel construction is a dangerous job, but having to bore one under Lake Ontario makes it even more difficult, according to a tunnel subcontractor.

The main drilling of the pedestrian tunnel at the Billy Bishop Airport in Toronto has begun, but not without the unique challenges that come with digging a hole underneath a large body of water, said Technicore Underground vice-president Gary Benner, the company contracted to excavate the tunnel that will connect pedestrians from the mainland to the airport terminal.

“As the excavation deepened and we got into the rock, there were quite numerous leaks,” Benner said.

The leaks had to be plugged and could’ve led to more hazardous safety issues, according to Noel Reilly, a representative from LIUNA Local 183 who trains individuals on tunnel safety and how to use the self-rescuer device.

“Our biggest concern with working in a tunnel was fire,” he said. “There’s a lot of voltage going on down there and it’s a wet and damp atmosphere.”

Toronto’s harsh winters also made for uncomfortable and unsafe working conditions as the water froze and ice began to form on the walls of the shaft.

“It would look like Niagara Falls with big chunks of ice falling down so we had to knock all the ice off,” said Benner.

He added that excessive rock movement in the rock wall was also an issue with the project after equipment was used to measure the movement on the rock wall.

“We added additional anchors and then there was still movement in the wall…a decision was made to put in another set of supports across the shaft,” added Benner.

Any individual who goes down into a tunnel is required to complete a tunnel rescue training course conducted by Local 183 on how to properly use the self-rescuer respirator. The device provides a source of oxygen in the event that oxygen levels are low and harmful gases are present.

“I know about 16 people who’ve put them on over the years,” said Reilly. “They put them on properly and everything was good. They do work and they will save your life.”

The device used at Technicore is a model produced by Drager, a German company that makes breathing and protection equipment that’s widely used by divers, firefighters and miners.

Costing approximately $950 per unit, the self rescuer takes in exhaled air, filters it with a potassium dioxide chemical and releases it into the breathing tube as usable oxygen.

Under “normal working conditions” such as walking, the device can last one hour, but its lifespan can be cut down to 15 minutes under more strenuous activity because the individual is breathing more aggressive.

“If I’m stressed out, I’m going to be breathing faster. If I’m breathing faster, I’m going to burn through the chemical faster,” said Reilly. “Once I burn through the chemical, that’s it. It’s finished and hopefully I’m at the top of the shaft by then.”

The 800-foot tunnel is on schedule to be completed and operational in the spring of 2014.