Cause of collapse identified in Muskrat Falls

An investigation into an industrial accident at Muskrat Falls last year suggests a deficient shoring system and possible use of poor material is to blame.

Nalcor Energy released a report completed by Vancouver-based aDB Structural Engineering on Monday.

Last May, near the end of a concrete pour into a powerhouse draft tube, the support structure failed, spilling more than 500 cubic metres of concrete. The collapse resulted in seven workers — concrete finishers, labourers and a foreman — falling directly into the concrete, with one fully submerged.

“The worker that was submerged by concrete was able to remove himself from the concrete with the help of a nearby coworker. The rest of the workers were able to walk away from the scene of the collapse,” reads the report.

In a news release, the Crown corporation says it has completed work to avoid a similar incident.

“Nalcor’s number one priority is the safety of workers and the public. We encourage all workers and contractors to report any safety issues or concerns to us,” Nalcor president and CEO Stan Marshall stated. “Nalcor remains committed to providing a worksite where everyone chooses to follow our safety protocols and live our values.”

Witnesses interviewed say they heard cracks and pops before a quick collapse resulted in them falling into the debris.

“Everything went extremely fast, we all went down in seconds,” stated one worker.

“Heard a pop, then crashing sounds, and was sucked into a big hole,” another noted.

The speed at which the collapse occurred, aDB stated, is indicative “that each section of the shoring was at or near ultimate capacity” causing a domino effect of failures within the formwork.