"To me that's just unconscionable on the operators' part," said Kevin Stricklin, of the federal Mine Safety and Health Administration. "They are not respecting methane gas."
On Saturday, investigators will inspect two methane monitors and a data recorder recovered from the mine in Montcoal to see if the monitors had been disabled before the April 5 explosion. They are expected to share the findings Tuesday with families of those killed.
Officials with Virginia-based Massey have repeatedly denied shutting the monitors off so crews could keep cutting coal when they encountered pockets of gas.
Records obtained by The Charleston Gazette show at least four of the 16 incidents cited by MSHA are part of an ongoing criminal investigation into the explosion, including two violations in September 2009.
At that time, MSHA also cited Massey's Performance Coal Co. for failing to properly train workers in how atmospheric monitoring systems should work. The inspector called it an "unwarrantable failure to comply with a mandatory standard."
Federal rules require methane monitors to be recalibrated every 31 days, but on the occasions cited, that was not done and the concentration readings were wrong.
After the Upper Big Branch explosion, a state mine safety panel proposed a rule requiring operators to check methane monitors on machines at the mine's face within every 15 days, recalibrating them as necessary.
Investigators suspect methane and highly explosive coal dust combined to give the April 5 explosion its power.
Massey claims a large crack in the floor could have allowed methane to suddenly surge into the mine, saying it experienced such surges in 2003 and 2004 without any injuries.
But Ron Wooten, director of the West Virginia's Office of Miners' Health Safety and Training, said a preliminary review of data does not indicate a sudden rush of methane. It does, however, indicate someone shut the longwall mining machine down about 90 seconds before the blast, he said.
Investigators have been unable to determine why; the miners who could have answered that question were all killed.