A methane-containing tank that caught fire at the Billings wastewater treatment facility early Tuesday was extinguished by the Billings Fire Department about two hours later.
Reported at 1:31 a.m., the fire prompted officials to close surrounding areas to public access, including a portion of Bench Boulevard, due to initial concerns that the methane-fueled fire could cause a larger explosion.
The fire caused about $15,000 in damage, Deputy Billings Fire Marshal Jeff McCullough stated in a press release later Tuesday, and the cause remains under investigation. Billings Public Works Director Dave Mumford said Tuesday morning that the methane in the tank may have been ignited by the electrical system.
The tank that ignited is a secondary digester, a holding tank in which microbes break down sewage and release methane during the process.
The methane is then either used to run a generator that powers the plant or is flared off. No flaring was taking place when the fire began, Mumford said.
Firefighters originally planned to close a pipe valve near the fire that delivers methane from the digester tank that had ignited, Assistant Billings Fire Chief Pepper Valdez said shortly after it was extinguished.
"We sent the suppression team in to suppress the fire and close those valves," Valdez said. "The valves didn't want to close, so 'Plan B' was to go further down the line."
A safety team from the water treatment plant was eventually able to enter the building and close a different valve, Valdez said.
"We actually train for this, so it was pretty straightforward," he added.
Officials at the scene initially believed that a methane storage tank had ignited. Mumford later clarified that no methane is stored on the plant property and that he isn't aware of any possibility of such a fire causing an explosion.
"I'm sure they err on the side of caution and safety while they're trying to figure things out," he said, adding that volatile chemicals associated with the treatment plant's operations are stored in a separate building from where the fire broke out. "The fire would have to spread quite a bit to get to the chemical buildings."
Nonetheless, the area near MetraPark was cleared and Bench Boulevard to Hilltop Road in the Heights were closed to the public while firefighting operations were underway. Billings fire and emergency management officials used an entrance to the plant just west of the Dick Johnson Bridge as a staging area for their incident-command operations while the tank burned about a half-mile away.
Two engines, a fire truck and a battalion chief were staged closer to the fire, inside the plant property, Valdez said.
Fire officials did not immediately have an estimate of the amount of damage caused by the fire. Mumford declined to guess at any dollar amounts, but said there was "significant damage" to the tank's lid and some other components.
The fire burned so hot, he added, that he's uncertain whether enough evidence remains to deduce the cause of the fire.
Despite the damage, Mumford said there will be no disruption to wastewater treatment services.
"The whole process is still working, so we are able to bypass the damaged area," he said.
The ongoing construction at the plant is not affected by the fire, Mumford added.
Yellowstone County Disaster Emergency Services, along with the sheriff's office, fire department, Billings Police Department and the Montana Highway Patrol responded to the fire.