The cause of the deadly fire and explosion at Robbins Lumber Mill in Searsmont on May 15 has been ruled accidental by the Office of the State Fire Marshal following an initial investigation.
In a Tuesday update posted to social media, officials said they believe the fire originated in the area of the unloader mechanism at the base of the silo.
Before firefighters fully contained the smoldering fire, a buildup of suspended particulate material ignited, causing an explosion inside the silo, according to officials. The blast lifted the silo off its concrete base and released large amounts of sawdust and other debris.
The silo then toppled, and the fire quickly engulfed the surrounding area. It spread rapidly to nearby buildings and structures within the mill, causing extensive damage across the complex.
Investigators from the Office of the State Fire Marshal and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives worked at the scene through the Memorial Day weekend, pausing to honor fallen military members and Morrill Firefighter Andrew Cross, who died in the blaze.
Several people were injured in the blast at the family-owned business, located in the heart of the Waldo County town at 506 Main St.
Investigators found that the facility’s fire suppression system, located near the top of the silo, did not activate because temperatures at that elevation did not reach the activation threshold after the fire started at the base.
“Based on the information obtained to date, the cause of the fire is considered accidental,” the Maine State Fire Marshal said in its Facebook post.
Over the weekend, crane operations were used to move the silo structure, allowing investigators access to key areas for evidence recovery.
Next steps
In the coming months, investigators plan to return to the facility for a more detailed examination of the unloader systems.
That work may include additional testing in coordination with insurance representatives and other technical experts to further determine a cause, according to the Fire Marshall.
The investigation is expected to continue with follow-up analysis, testing, report writing and coordination among agencies. The Fire Marshall will coordinate with the National Institute for Occupational Safety and Health regarding firefighter safety.
