How hydro workers got our power back on in 52 hours

After three tornadoes ripped through the Ottawa region Friday, leaving 180,000 homes in the city without power, Hydro Ottawa boss Bryce Conrad had a grim phone conversation with his provincial counterpart.

"Our call was fairly devastating," said Darlene Bradley, acting chief operating officer for Hydro One.

• Power coming on in 'dribs and drabs' but could take a day or two

The Merivale transformer station sitsnear the Greenbank and Hunt Club area, where one of the tornadoes touched down. Roofs were ripped off buildings, the porcelain insulation that protects power cables was smashed, and debris was everywhere. Not a single piece of equipment was working.

"I've worked at Hydro One for 30 years, and I've never seen anything like that," Bradley said. "There was nothing that was usable."

And yet, a little more than 48 hours later, the number of homes without power was down to just fewer than4,000.

How did they do it?

Disaster and recovery in Ottawa-Gatineau

6 years ago

Duration 2:47

Residents are combing through the wreckage of their homes and reaching out to help neighbours after tornadoes ripped through Ottawa-Gatineau on Sept. 21.

Rejigging the system

In addition to the damage at the Merivale station, 90 hydro poles had fallen, pulling wires down with them. Transmission towers were folded in half.

So late Friday, Hydro Ottawa crews mostly workers who had finished their shift Friday afternoon and stayed on when the weather warning arrived began working on the poles and clearing debris. Crews laboured tirelessly around the clock.

Getting those wires up would give some people their power back, or at the very least, get the network ready for the flow of power.

In the meantime, Hydro Oneinvestigatedhow to divert power from the Hawthorne transformerstation to the dark areas of the city.

"It's like running an extension cord to your neighbour's house so you can have power while you fix your own house,"Bradley said.

• Praise for hydro workers as power returns

Normallythe city's electricity network works at 60 or 70 per cent capacity, leavingroom to add load to other parts of the system. That strategyworked to an extent.

By Saturday morning, the combination of rerouting power and repairing poles had restored electricity to 30,000 customers. Hydro workers continued to have success through the day and night on Saturday. By Sunday morning, power had been restored to a total of more than 100,000 homes.

Why does my neighbour have light?

But the workaround wasn't perfect.

Rerouting didn't always allow Hydro Ottawa to bring power to whole communities. In some cases, just a few small neighbourhood distribution systems, or circuits, received power. That meantsome residents were burning candles while their neighboursacross the street had the lights on.

It was confusing and frustrating for many.

Worse, hydro officials always knewthe rerouting wouldn't bring power to every home. At some point, they needed to flow power through that Merivale station, which seemed impossible at the start of the weekend.

Like a puzzle

But Hydro One engineers and technicians had been thinking about the problemas their crews handled the dangerous work of cleaning the station.

Merivale acts as a sort of bridge between the provincial and municipal hydro networks. High-voltage power comes into the Hydro One station, gets transformed into lower-voltage power, and goes out through multiple wires to about 20 Hydro Ottawa substations, which in turn feed power into communities and, eventually, into every single home in Ottawa.

If the rest of the city was going to get power, the brains at Hydro One were going to have to build a different kind of bridge between the Hydro One and Hydro Ottawa networks.

"We needed to find a way to use the infrastructure that was there to accept power, and get it back out again," Bradley said. There wasn't exactly a single "Ah ha!" moment, she said it was more like a puzzle that different people worked on.

The solution was to repair a piece of equipment that conducts electricity, called a busway, and MacGyver it to allow power tocome in from other sources, do a sort of loop-de-loop around the busway, and then get shot out of Merivaletoward Hydro Ottawa's substations.

There was no guarantee it would work. And this sort of workaround is unusual at the best of times, let alone given the Merivale station's sorry state.

3rd time's the charm

By Sunday morning, Hydro One thought they could do it and told Hydro Ottawa to expect a power-up around noon.

But Hydro One kept running into snags, finding morerepairs to do. Noon turned into 4 p.m., which turned into 7 p.m.

"It doesn't come, it doesn't come, it's excruciating," recalled Conrad of Hydro Ottawa. "It's causing a certain amount of grief we still have 77,000 customers without power."

Then, around 8:30 p.m., the power startedto flow into Hydro Ottawa's system. They decided to flip the switch for Longfields station,and it worked, at least according to the command centre controls. Theimmediate responses on Twitter told them it worked forcustomers, too.

"It's borderline euphoria at that point," Conrad said.

Then, one by one, power flowed to another dozen substations to the south and west, with Twitter announcing the lights coming onfrom Rideau Heights to Woodroffe. By 11 p.m. Sunday, most homes had power.

What's next

There were still about 3,900 homes without power as of Monday evening. Those may be among the most difficult to repair, with work needed on individual lines into homes damaged by fallen trees and high winds.

The system is working at full capacity, which isn't ideal. Conrad pointedout it's lucky we're not experiencinga heat wave, because thesystem couldn'thandleair conditioners. And another severe weather incident in the coming days could wreakhavoc onthe system.

Hydro One won't know for a while what it will take to fully restore the Merivale station,Bradley said, but it'staking steps "to make it more resilient every day."

Still, the short-term fix forthe pastweekend's worst-case-scenario event is nothing short of a feat of engineering under pressure.

"On Saturday morning, what I was being told was, 'This is bad this is really, really bad,'" said Conrad. "So to be in a position a little more than 48 hours later where we can light up most ofthe city is a pretty good feeling."