HELENA, Mont. (AP) -- Federal health and safety regulators have opened an investigation into an explosion and fire at an eastern Montana oil recycling facility that injured three workers and was still burning five days after the blast.
Two investigators from the Occupational Safety and Health Administration arrived at the Custom Carbon Processing salt water disposal and oil reclamation facility near Wibaux this week, said Department of Labor spokeswoman Deanne Amaden.
The explosion and fire happened Saturday as the contents of a tanker truck were being pumped into the facility while the three workers were installing insulation.
The OSHA investigators are looking into whether the company was following safety procedures and whether the explosion could have been prevented, Amaden said.
"It doesn't necessarily mean the company had a violation," she said.
An OSHA investigation is thorough and typically takes up to six months, Amaden said.
Green Oasis Environmental Inc., the Alberta, Canada-based parent company of Custom Carbon Processing, has not made any public statements on the explosion and fire. Company officials did not return a call for comment Wednesday.
The tanker was still on fire Wednesday, with flames shooting out of two vents, preventing the state fire marshal from determining a cause and hindering the OSHA investigation.
After keeping a safe distance until the threat of the fire spreading had passed, firefighters on Tuesday sprayed foam into the burning tanker but failed to extinguish the flames.
Wibaux Fire Chief Brian Nelson said Wednesday he is not sure what is in the tanker to keep it burning for five days, and there will be no further attempts to put it out because of the uncertainty.
Fire officials will monitor the fire around the clock until it burns itself out, he said.
Custom Carbon Processing converts waste called slop oil from the oil producing process that would otherwise be discarded and turns it into pipeline-grade oil the company sells to oil buyers.
The facility eight miles outside Wibaux, at the western end of the Bakken oil boom, was a former oil well and then a disposal well. It opened in September as Michels Salt Water Disposal and Oil Reclamation Facility capable of reclaiming slop oil.