Subway service has resumed between Union and Bloor stations on Line 1 following an extended closure to investigate a leak found in the tunnel near College Station early Tuesday morning.

An unknown substance was found leaking into the tunnel from an expansion joint about 500 feet north of College Station shortly after midnight, prompting the closure.

Though TTC officials were initially concerned that the liquid may have been diesel fuel or another flammable substance, spokesperson Brad Ross tells CP24 that it was likely just “ground water with some latent oil that was sitting there” mixed in.

During the closure TTC CEO Andy Byford, Ross and a number of other senior executives were on hand to assist TTC workers in directing weary passengers at affected stations. Police were also called to the Yonge and Bloor streets area to assist with crowd control.

“I would just like to say to everyone ‘Thank you so much for your patience.’ We had to put safety first given the smell and the apparent nature of this liquid coming in and what we will now have to get to the bottom of is where the hell did this come from and what was it,” TTC CEO Andy Byford told CP24 on Tuesday afternoon. “Was it just contaminated ground water or was it in fact leaking from a facility in one of these buildings? All I know is it made an absolute mess of our morning peak.”

Source of leak a ‘complete mystery’

There was some construction work being completed in College Station on Monday, however Byford said that the leak is not believed to have been caused by the TTC and remains “a complete mystery” as to its source.

As part of its preliminary investigation, the TTC has contacted the city to determine whether there are any underground fuel tanks in the area and sent a team to the basement of a nearby hotel known to have fuel tanks.

About 70 shuttle buses were running between Rosedale and St Andrew stations during the closure.



Remember for instant breaking news follow @cp24 on Twitter.