Vault at centre of blasts was just inspected in the fall: Toronto Hydro

The vault at the centre of a series of blasts that sent plumes of smoke billowing into the Financial District on Monday had just been inspected in the fall.

The cause of the explosions is not yet known, Toronto Hydro spokeswoman Tori Gass told CityNews on Tuesday, adding that’s it too early to say if flooding is to blame.

“That is the number one question that is on everyone’s mind right now but unfortunately we don’t know,” Gass said.

Fire and smoke caused extensive damage to the 17-year-old vault. The fire also burned existing equipment.

Gass said that everything was in working order during the fall inspection.

“This is not something that happens often,” she said.

“This is an extremely rare occurrence. We want to make sure everyone knows this isn’t something that’s going to happen all the time. It’s just we don’t know what exactly has happened just yet.”

Until the most recent blast, there had been no fires in Toronto’s 1,100 underground vaults last year or this year.

Monday’s blasts shut down the area of Yonge and King streets, and forced streetcars and drivers to divert around the area.

The first explosion was heard shortly after 5 p.m. Heavy black smoke was seen billowing from a set of grates outside a Royal Bank office building. The chaotic scene continued with sounds of underground blasts as officers herded crowds away from the scene.

“Did you hear those sounds? Those are explosions,” an officer was heard yelling to bystanders.

No one was injured, Toronto Fire Services said.

Police cruisers blocked off streets in the area and officers were seen wearing surgical masks as smoke hung in the air.

The incident shut down King subway station and caused several streetcars to take detours.

The Royal Bank office building and parts of an underground shopping concourse were evacuated due to heavy smoke, fire officials said.

By Tuesday morning, hydro crews were on scene to repair the vault. However, they were forced out when heavy smoke was seen around 1:30 a.m. Toronto fire crews were called in and had to secure the area, delaying the repair work.

King reopened late Tuesday night.

Gass said in addition to replacing the damaged transformers, Toronto Hydro would also be switching out a second transformer soon.

On Monday, Toronto Fire Platoon Chief Kevin Shaw said firefighters were able to contain the blaze within an hour. He added that once hydro workers were able to cut the power to the vault, firefighters would be able to go in and douse any remaining hot spots.

“It’s energized electrical equipment that’s in the vault, it overheats, starts melting down … so that’s where you’re hearing the crackle and the popping,” Shaw told reporters Monday night. “There (were) visible flames out of there probably a half hour ago, but we feel that it’s definitely under control now.”

Shaw said the fire’s cause would likely be determined once hydro crews could get access to the vault.

“It could be dampness, water or an aging hydro vault, or all of the above,” Shaw said. “It all leads up to one of these fires.”

He said he has seen worse hydro vault fires downtown, but added that crews had to take precautions because it happened during rush hour.