01/09/2014 02:30 EST | Updated 03/11/2014 05:59 EDT

Toronto ice storm timeline: From the lead-up to the clean-up

Executives from Toronto Hydro briefed reporters Thursday on the process that unfolded as the ice storm struck the city ahead of Christmas and how they worked to get power restored for 300,000 customers.

Wednesday, Dec. 18 to Friday, Dec. 20, 2013

Ben LaPianta, the executive vice president of grid operations, said that Toronto Hydro began tracking the storm on the Wednesday before it struck the city four days later.

"We knew the storm was coming out of the central U.S., it was a warm air mass and we knew that it was going to collide somewhere in Ontario," LaPianta told reporters.

But LaPianta said there were many questions about when the storm would arrive, precisely where it would cause problems and what the precipitation mix was going to look like.

"By Friday, we knew the storm was going to collide somewhere over the Greater Toronto Area, but again the freeze-line was undetermined and of course, the volume of precipitation was undetermined."

Toronto Hydro began to "mobilize," by ensuring that key staff had the information they needed to stay in touch once the storm hit, LaPianta said.

Saturday, Dec. 21, 2013

The forecasts were suggesting that Toronto was going to see 30 to 40 millimetres of freezing rain. And the predictions were accurate, with the city being hit with 33 millimetres, according to LaPianta.

"We knew by Saturday morning that it was a certainty," LaPianta said.

The rain started falling and there was "some disturbances" on the system late on Saturday night, LaPianta said, though the utility was then not receiving more calls than they would expect during a typical summer-season storm.

Toronto Hydro declared a Level 2 emergency, which allowed them to bring in extra crews to deal with some of those initial problems.

"The ice had just started to build and what we were seeing was some flashing over, some short-circuiting of our equipment," he said.

Sunday, Dec. 22, 2013

Things started to get worse in the early hours of Sunday.

"By 2 a.m., it was evident that this was going to be a catastrophic event," LaPianta said.

LaPianta said that the city was getting about 2.5 mm of ice each hour, with about 10 millimetres of ice already on power lines by 3 a.m.

That was causing "considerable short circuiting of the equipment" and led to a number of fires.

"The horizon was orange with colour, there was a lot of burning going on and branches were starting to come down, the equipment was failing," said LaPianta, who was then driving into work and observing what was going on.

Toronto Hydro declared a Level 3 emergency at 3 a.m. that day. That allowed the utility to suspend normal work hours, as well as to open its emergency operation centre, as well as so-called local incident command centres.

The utility had its first conference call with Toronto’s Office of Emergency Management at 6 a.m., LaPianta said.

LaPianta said the full magnitude of the storm’s damage was beginning to become known:

- More than 300,000 customers without power at the height of the storm.

- Toronto Hydro was dealing with 100 times the number of incoming calls that it would normally receive.

- Eight hundred traffic lights were out.

- Five hundred wires were down across the city. In 160 cases, police were having to guard over downed wires.

"Live wires were found, the system didn’t always remove a circuit from energization — that’s the nature of an ice storm," said LaPianta.

That Sunday, LaPianta said there was critical infrastructure that needed to have power restored.

Some hospitals, including Sunnybrook, had to go on backup power, as a result of the storm. Several water pumping stations also were without power.

LaPianta said Toronto Hydro made its first "mutual aid" calls on Sunday morning, which was the start of an effort to bring in crews from other municipalities — including some from the United States and from other provinces. Eventually, hundreds of additional workers came to Toronto to help.

Tuesday, Dec. 24 to Wednesday, Dec. 25, 2013

Anthony Haines, the president and chief executive officer of Toronto Hydro, said the utility was able to restore power to about 75 per cent of affected customers within about 48 hours.

Haines said that was only possible through the hard work of hydro crews and the rest of the utility staff involved in responding to the emergency.