Subway re-opens following mystery leak at College Station

CTV Toronto: Big leak closes TTC subway Fears of a flammable substance on Toronto's main subway line prompted a closure that lasted several hours. Natalie Johnson has the latest.

A section of the Yonge subway line has finally re-opened after being shut down for most of the day because of a leak on the tracks near College Station.

TTC officials announced the re-opening around 1:30 p.m. ET in a tweet:

The leak of an "oily substance" was discovered shortly after midnight Tuesday.

TTC CEO Andy Byford went down to the track level and reported that the liquid was not just dripping from the ceiling; it was pouring through.

Transit officials were forced to shut down the subway between Bloor and Union stations while firefighters and city crews scrambled to find the source of the spill.

At first, it was thought that the leak was gasoline, kerosene or oil, based on its odour. But Byford told CTV Toronto the leak appeared to be a hydrocarbon substance coming from a boiler room or basement tank of a nearby building.

The shutdown led to morning rush hour commuter chaos, as subway users were forced to shift over to the University-Spadina line, walk, or take one of 70 shuttle buses.

TTC workers, meanwhile, spent most of Tuesday working to pump the liquid off the tracks and to stop any more water from coming through the ceiling.

Byford said crews applied 300 litres of grout to the expansion joint, from where the substance was leaking, and were finally able to seal it off.

With files from CTV Toronto's Natalie Johnson and Zuraidah Alman

Oil-like substance leaking into the tunnel north of College Station (Brad Ross / TTC) 

North of College, 'oil-like leak' at track-level (Brad Ross / TTC)