State and federal officials are back at work inside the southeastern Kentucky mine where five men were killed last month.
Mine company workers finished repairing the ventilation system yesterday.
The investigation inside the mine was halted earlier this week after the U-S Mine Safety and Health Administration advised the air in Kentucky Darby Mine Number One was unfit to breathe.
The seals are designed to contain methane and other gases out of active mining areas. Three of the miners killed in the accident on May 20th survived the initial explosion but later died of carbon monoxide poisoning.