A roof collapse that killed a West Coast coal miner last September could not have been foreseen, a Labour Department investigation has concluded.
Former Kiwis rugby league player Bernard Green, 47, died after a shaft collapsed 800m underground at the Roa Mine near Blackball.
Nine other miners escapeduninjured after the accident 30km from Greymouth on September 8.
Labour Department workplace services manager for Canterbury and the West Coast, Margaret Radford, announced today the department would take no further action after "thorough investigations".
Mrs Radford said the investigation found that the roof collapse that caused Mr Green's death was not something the mining company "could reasonably have known about or prepared for".
Mrs Radford said the fatality was caused by a "number of complex factors acting in unison".
Mr Green's death was the result of a sudden and unpredictable collapse of the roof. A wide excavation had put tension on the mine roof and pillars, and along with "corresponding geological factors" the rock fall entered the level where he was standing.
The mining method used by the company had been successfully employed for decades before the September 8 incident.
"It is our conclusion that this tragic incident was not reasonably foreseeable and no one can be held responsible," Mrs Radford said.
The mine operating company, Roa Mine Ltd, had health and safety systems in place, and competent and experienced managers and employers, she said.
A check by an elected health and safety representative on the work site just hours before the collapse had raised no concerns about the stability of the area.
Mrs Radford said after the roof collapse, the company undertook extensive research to study ways to prevent a recurrence.
Mr Green's family, union representatives and the mining company had reviewed the department's investigation report, which would now be provided for a coroner's inquest.
Roa is the largest privately-owned coal mine on the West Coast and is the country's only private coal exporter.
It is a century-old mine reopened over the last decade, digging back into old workings that tapped two major coal seams.
