State officials offered a sort of combination of other theories about where the methane that fueled the initial ignition came from.
The McAteer team said the methane came from the mined-out area behind the longwall, while MSHA said it flowed from a gas reservoir under the Upper Big Branch floor.
State investigators said the methane was "mostly liberated" from cracks in the mine floor that were located in areas behind the longwall. But they also rejected the theory put forth by Massey Energy officials that the blast was caused by a huge flood of methane from those floor cracks.
"Rather than a dramatic outburst, it is more reasonable to believe that methane was liberated along the face in increased amounts caused by the breaks in the floor and from the gob, and that this increased liberation caused an undetected buildup against the gob," the state report said.
And like previous reports, the state's review found that poor planning of Upper Big Branch's ventilation system - meant to flow fresh air through the mine to sweep away methane and coal dust - contributed to the disaster. The report said West Virginia regulators need more authority over mine ventilation, but also called on the industry to take the lead in dealing with such issues.
"Coal operators must take a more proactive approach to the ventilation of each coal mine under their authority and responsibility," the state report said. "The industry has taken a step back over the years in proper planning and preparation as long-term plans are developed. The operator must once again lead the way in doing the hard work and extensive work necessary to properly ventilate each mine."
The key difference in the state's new report, though, was in its tone and style.
McAteer's teams blasted Massey Energy's management of Upper Big Branch as "profoundly reckless." The UMW's report was titled, "Industrial Homicide." MSHA said Massey "routinely ignored obvious safety hazards" that led to "the tragic death of 29 miners."
State investigators included no such condemnations of the mine's safety practices or denunciations of its corporate management in their report.
The state report includes extensive discussion of the interplay between coal seams, sandstone and accumulations of plant fossils. Investigators attached two detailed appendices describing local geology.
But the state's report includes only a few paragraphs that vaguely summarize the violations inspectors found, with no specific discussion of what role those violations played in the disaster.
And when outlining general problems that inspectors found at Upper Big Branch after the explosion, state officials used much more measured language.
For example, the state report concurred with other investigations that found one contributing factor was the failure to spread adequate amounts of crushed limestone, or "rock dust," to keep coal dust from exploding.
But state investigators explained that, "Based on the available information and records, it is believed that some areas would be rock-dust deficient at any given time. Mines should be pro-active in the rock-dust program instead of waiting until rock-dust deficient locations have been identified."
The state report also agreed with previous reviews that found mine managers at Upper Big Branch frequently did not ensure that safety hazards were documented in required record books and promptly fixed.
In its report, the state agency explained such problems by saying, "during the investigation, testimony varied as to how workers performed their fireboss and supervisory duties. It is impossible to draw solid conclusions other than that additional training should have been given to assist firebosses and supervisors in their understanding of the plans and importance of following all approved plans relating to their specific areas of responsibility."
State inspectors issued individual citations to mine foremen Terry Moore and Ricky Foster, alleging that they neglected to ensure coal-dust accumulations were cleaned up. They face potential fines of up to $250, officials said.
The state's report said inspectors have moved to revoke the mining license of a third Upper Big Branch employee, but declined to identify that person because he hadn't been served with the revocation notice yet.
West Virginia inspectors also issued an individual citation to an MSHA employee, Ted Farrish, alleging that he took a cigarette lighter underground in July 2010 during the Upper Big Branch probe. State and federal laws prohibit all smoking materials in underground mines.
The state's report did recommend that the coal industry consider moving toward the use of containers of water or crushed stone in strategic locations inside underground tunnels, to help keep small gas or dust ignitions from turning into major disasters.
These so-called "passive barriers" are widely used in other mining countries, and have been recommended for years by safety experts, but are not required in West Virginia or elsewhere in the United States.
"Additional defenses are needed to prevent propagation of a methane explosion into a coal dust explosion," the state report said. "Explosion barriers have been studied for years and have been found to be effective in stopping an explosion."
McAteer, whose independent team faulted the state agency's inspections of Upper Big Branch prior to the disaster, credited the state for "being honest about its own failings" in the new report. He cited a detailed description of how parts of the mine's longwall section were not "rock dusted" for months, a problem state inspectors should certainly have seen.
"But the bigger problem is that the state simply doesn't address the systematic failures of the company at all," McAteer said after reviewing the new report. "It's all well and good to say, 'We need more training for company mine examiners.' But there was training. There was just a failure to do the work properly.
"I think the report does not go far enough in addressing the problems that exist in the state political system and how to regulate large industries," McAteer said.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.