The US House Education and Labor Committee released the results of its investigation last week and referred the review to the US Department of Justice.

US representative George Miller of California said the committee reached several conclusions in its examination, including operator oversight.

“The findings of this investigation demonstrate that the Crandall Canyon tragedy might have been avoided at several key moments,” Miller said.

“They suggest that the mine operator did not act in the interests of the safety of its employees and that the Mine Safety and Health Administration failed these miners and their families.”

Working in tandem with a geoengineering consultancy, the staff of the committee found that it was "likely" that the events at Crandall Canyon were related to a "flawed plan" of retreat mining in the area of the mine where the deaths occurred – a plan that should never have been submitted by its co-owner, UtahAmerican Energy, and should not have gained MSHA approval.

Additionally, the committee found that the operator may have "wilfully misled" federal regulators on information that could have impacted its decision whether or not to approve the mine's retreat mining plans.

“Nevertheless, had MSHA done its due diligence, it likely should have recognised the flaws in the plan and refused to approve it," Miller said, adding that his decision to refer the case was in "full recognition" of the fact that nine workers died.

“The fact that UtahAmerican Energy may have misled MSHA in no way absolves the agency of its decision to approve the deadly retreat mining plan amendments.

“MSHA officials must not sit on their hands and wait for mine operators to bring information to them."

Crandall Canyon's co-owner, UtahAmerican Energy, is a Murray Energy subsidiary. The operation, also co-owned by Intermountain Power, has since been closed.

UMWA responds in support

Following the report's release, United Mine Workers of America international president Cecil Roberts said the findings are a confirmation of the union's stance – the submitted plan was flawed and should not have been submitted, and MSHA should not have approved it.

“The committee has referred some of its findings to the Justice Department for further investigation,” Roberts said.

“We believe it is now incumbent upon the Justice Department to fully and completely investigate these matters, without regard to where that investigation may lead.”

Roberts added that despite the many analyses and reviews of the accident, the fact remained that nine miners lost their lives.

“Our nation and its leaders can no longer watch these tragedies unfold, wring our hands and say, 'how horrible' – then stand aside and do little to prevent them,” he said.

“Further congressional action to prevent tragedies like Crandall Canyon from happening is needed, and needed now.

“Rep Miller and others in the House have taken the first step by passing the Supplemental MINER – or S-MINER – Act. I urge the Senate to take up this critical legislation without delay, so that America’s miners will at least have some sense that their government does, in fact, care about whether they live or die."