The Montreal company that supplied the stage that collapsed at Bluesfest Sunday began dismantling the remains of the structure late Tuesday afternoon, after getting Ontario government approval.

Inspectors from Ontario's Ministry of Labour had been combing the wreckage for clues as to why the stage fell.

The ministry had requested that all work be stopped on the stage until the area had been secured. No work was allowed until the ministry gave its approval.

It also instructed the company to draft a plan on how to safely dismantle what's left of the stage. The plan was also required to be approved by a certified engineer in the province of Ontario and with that reviewed by the ministry and approved, they can now take it down.

Stephane Berger, the owner of the stage company Groupe Berger, said it will take up to a week to finish the job.

"It could take three to five days, up to a week," he said. "It's not something that we do every day. We will see how things go." 

Ministry officials have ordered festival organizers to provide copies of any videos taken by their contractors of the collapse of the stage and also engineering documentation for the stage, said ministry spokesman Matt Blajer.

The band Cheap Trick took the stage at about 7 p.m. Sunday and played for 20 minutes when the storm clouds rolled in. The band hastily left the stage and, moments later, high winds caused the structure to collapse.

Some 10,000 people in attendance took shelter, many at the nearby Canadian War Museum. Three people were injured but released from hospital on Monday.

Cheap Trick manager Dave Frey told CBC News the wind hit the stage "so hard that it just kind of creaked and groaned and then you heard rivets popping."

The specifications of the Mark III stage that collapsed say it can withstand gusts of wind as high as 120 kilometres an hour.

Ticket holders to get refunds

Cisco Ottawa Bluesfest executive director Mark Monahan said holders of day passes to Sunday's shows would have three options for their tickets:

  • Exchange the ticket for a day pass to next year's Bluesfest, once the lineups have been announced.
  • Exchange the ticket next week (July 25 - 30) for a day pass at the Ottawa Folk Festival, which runs from Aug. 25 to 28.
  • Get a full refund of the ticket next week (July 25 - 30)

Winds at the Ottawa Airport were recorded at 96 km/h, but Environment Canada said a downburst — a strong downdraft of air from a thunderstorm that spreads out in all directions when it hits the ground at much faster speeds — was likely the trigger for the collapse of the main stage.

Downbursts can potentially cause as much damage as a tornado.

Berger said it was "freakish weather" and not a structural defect that caused the collapse.

"Our explanation is that the wind was too strong. We got a report from the Weather Network stating wind gusts up to 140 km/h and obviously we were right in the middle of the storm," he said.

Four smaller stages at the site — built by L'Assomption, Que.,-based Stageline — remained standing during the storm. Yvan Miron, the CEO of Stageline, said his stages come delivered in a semi-trailer and then use a hydraulic system to take shape, eliminating the need for much of the screwing and bolting involved in other stages.

"Any inspector will approve the information but they don't necessarily have all it takes to really understand how it should be installed," said Miron.

Bluesfest executive director Mark Monahan said the stage was inspected daily by Bluesfest staff. Monahan said the storm was a "freak situation" and said he thought onsite staff did a good job of handling the situation.

He said festival organizers would consider making changes to how it co-ordinated with weather officials but said they would await the findings of the ministry.

The death of a woman and injuries to over a dozen others after the collapse of a stage at the 2009 Big Valley Jamboree in Camrose, Alta., led to changes in how the organizers prepared for future events.

The following year, organizers used the same type of structure they had used in 2009 — made by a different company than the Bluesfest stage — but added extra weight and braces as precautionary measures.

Larry Werner, the producer of the Big Valley Jamboree, said organizers are now more cautious when it comes to weather.

"The big thing is to monitor the weather and really don't trust it," said Werner. "We shut our stage down last year on a Friday night ... we had clouds roll in and the wind picked up and we probably could have played through it but we chose not to."

"We shut the stage down. Peace of mind for everybody in the concert bowl and on that stage was huge, so I think we made the right decision," he said.