More than 75 firefighters responded to a blaze that cast thick, black smoke above a Dickerson power plant Saturday afternoon, a fire official said.
The fire started at the Mirant power plant on Martinsburg Road shortly before 2 p.m., according to Pete Piringer, spokesman for the Montgomery County Fire and Rescue Services.
Mirant spokesman Steve Arabia said there was a fire in the rubber lining of ductwork that transports exhaust from a coal unit to pollution control equipment.
The "scrubbed" exhaust eventually leaves the plant through a 700-foot smokestack, Piringer said.
The duct that caught fire affects one of the three coal units at Mirant, Arabia said. That unit will operate at half capacity until the completion of repairs. On Saturday, contractors had been repairing the unit, which already was operating at half capacity, he added.
Investigators determined that the fire was accidental, Piringer said, adding that the contractors could have caused the fire inadvertently. Residual debris from the scrubbing process also caught fire, Piringer said.
Arabia said Mirant has ideas of how the fire began, but he declined to discuss them. "We're still trying to nail it down."
No cost estimate has been established for the damage, he said. "We're assessing the damage and what it's going to take to repair it."
The fire did not affect the plant's ability to provide power to customers, he said.
Piringer said four firefighters received minor injuries while extinguishing the blaze. The firefighters were treated and released from Shady Grove Adventist Hospital.
"They essentially got some debris in their eyes."
Mirant evacuated 10 people in the plant, who were not injured, Arabia said.
Fire and rescue personnel from Montgomery, Frederick, Carroll and Loudoun counties spent several hours at the scene, Piringer said. They used catwalks and ladders to reach the blaze located about 60 feet above ground.
"It was challenging because it was elevated," Piringer said. "It's not your typical house where you can go in the house and up the front steps. The weather also was a factor because it was very hot."
The damage does not affect the plant's ability to comply with air quality regulations, Arabia said.
Arabia said residents should be assured that the fire was an isolated incident. "It certainly produced a lot of smoke, and people may have seen and wondered what it was," he said. "It was an unusual event at the station."
Mirant reached an agreement last week with the Sugarloaf Citizens Association to provide financial backing for a new environmental foundation. In exchange, the association will withdraw its opposition to a planned expansion of the plant that nearly doubles the station's electricity generating capacity.