Nickel mining giant Vale has wrapped up an investigation into the deaths of two miners last year.

Last June, Jason Chenier and Jordan Fram were killed underground while working at Stobie Mine.

The two were overtaken by a run of rock material or 'muck,' when they opened a gate and the material overflowed into the area in which they were working.

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Kelly Strong, vice president for Vale's North Atlantic Mining and Milling Operation. (CBC)

Kelly Strong, vice president for Vale's North Atlantic Mining and Milling Operation, said six factors were at work in that incident, including water management, ore mixing and operational controls.

"And when you look at those … one of those, in itself, wouldn't have caused the incident to occur," Strong said. "It's really the aggregate or the combination of all of those things coming together that really [caused] ... the run of muck to occur."

Strong said the company has a plan of action, including more than 30 recommendations to put control measures in place.

""These recommendations address things such as improved practice around water management, ore mixing, ore pass management, roles and responsibilities, training and awareness, hazard recognition and risk assessment, [as well as] auditing to validate the effect of risk controls."

The Ministry of Labour and the United Steelworkers union are conducting their own investigations. Both of those are still on-going.