The company said alterations to its ventilation plan have been approved by the Mine Safety & Health Administration (MSHA) and the West Virginia Office of Miners’ Health, Safety and Training. Air quality measurements are in compliance with the company’s approved ventilation plan.

Explosive levels of methane were found in sealed parts of the mine after a foreman admitted he falsified a safety examination of the sealed area, according to The Charelston Gazette

The foreman reportedly said he was forced to fake such records and is cooperating in a broader criminal investigation in which five other mine officials have been named. Patriot Coal said it was cooperating with the investigation. It disclosed information to the proper authority and will take appropriate action as the facts become more clear.