Federal report says firefighting tactics at Maine lumber mill explosion aided the blast

PORTLAND, Maine (AP) — Firefighters who responded to a fire at a Maine lumber mill used tactics that inadvertently contributed to a massive explosion that killed three people, according to a report from federal investigators.

The fire companies tried to extinguish the May 15 fire inside a silo at the Robbins Lumber mill in rural Searsmont, Maine, by injecting it with water — unaware of warnings from the manufacturer that doing so would be dangerous.

The silo then blasted skyward like a rocket as flames and a shock wave from the explosion hurled workers and firefighters away.

The firefighters didn’t know, the National Institute for Occupational Safety and Health wrote this month, that the silo was oxygen-limiting, a type of sealed structure that can become pressurized with combustible gases during a fire.

That kind of buildup is a known hazard in oxygen-limited silos, and both the manufacturer and fire safety organizations put out firefighting guidance warning against putting water or foam into such chambers.

“The document warns against spraying water or foam into the oxygen-limiting silo as it will force air in and may create a potentially explosive mixture,” the report states. “The application of water into the silo in this incident likely entrained oxygen into the silo headspace, stirred up dust within the contents, and caused it to become suspended in an explosive concentration.”

The report recommends that fire departments make sure firefighters choose appropriate tactics for silo fires and never direct water or foam into oxygen-limiting silos. It also states that more training is needed for fire departments about the hazards associated with different types of silos.

The blast also injured at least 13 people and the toppling of the silo engulfed the surrounding area in fire, investigators have said. The explosion took place in the small town about 95 miles (150 kilometers) northeast of Portland and triggered a response of 299 firefighters from 46 departments across a four-county area. It took them hours to contain the fire.

Representatives for Searsmont Fire & Rescue did not return phone calls seeking comment Tuesday. The department’s assistant fire chief, Wayne Woodbury, 76, died from injuries suffered in the explosion. Andrew Cross, 27, of the Morrill Volunteer Fire Department, also died. Alden Robbins, the co-owner of the mill, died from injuries weeks later.

Robbins Lumber representatives said on the company’s website that “no report can fully capture the heartbreak experienced by our community, nor can it lessen the tremendous loss suffered by so many.” The company is working with industry experts to rebuild its facilities, the statement said.

“Our objective is not simply to meet current industry standards, but to exceed them. We are committed to learning from this event and to doing everything we can to help prevent anything like this from happening again,” the statement said.

The National Fire Protection Association declined to comment on the report beyond saying it encourages firefighters to participate in the National Institute for Occupational Safety and Health’s work to improve safety investigations. The Maine Department of Public Safety also declined to comment.

Officials with the town of Searsmont said in a statement that a final investigation into the explosion is still ongoing.

“As investigations move forward, we should allow the facts to guide any conclusions. It is neither fair nor constructive to rush to judgment or to diminish the dedication of the firefighters who responded or the company that suffered such a devastating loss,” the statement said.

The Maine State Fire Marshal’s Office said in late May that rapid ignition of particulate material resulted in the silo explosion, which caused it to lift from its concrete base and release large amounts of sawdust and other materials. It said the fire and explosion were accidental.

The mill is a part of the historic lumber and wood products industry in Maine. The company has said it is a high tech lumber manufacturer that has been in existence since the 19th century.