A plume of smoke from the Penobscot McCrum factory is visible for miles.

When the Penobscot McCrum potato processing plant on the Passagassawakeag River in Belfast caught fire early Thursday morning, officials —- concerned about dangerous chemicals in the building —- had to quickly make decisions intended to keep the community safe.  

Those chemicals included 12,000 pounds of ammonia, tanks of propane and a couple of hundred pounds of sulphuric acid, according to Dale Rowley, director of the Waldo County Emergency Management Agency. Under the right — or wrong — circumstances, all of those chemicals are potentially deadly, he said.

“It’s probably one of the worst incidents we’ve had in quite some time,” Rowley said.

The potential for a mass casualty event in the heart of the city’s downtown led to far-reaching actions, including the cancellation of school for Regional School Unit 71, a district that includes the communities of Belfast, Belmont, Morrill, Searsmont and Swanville.

Fears of toxic fumes drifting across the river also led to the evacuation of the patients and residents of Harbor Hill, an assisted living facility located on the east side of Belfast. The U.S. Route 1 bridge, which carries thousands of cars a day across the river, was also closed for a period of time during the busy morning rush hour.

Ultimately, no mass casualty event happened, something that Rowley attributes in part to the thoughtful actions of Belfast Fire Chief Patrick Richards and the other firefighters and first responders.

Factory owner Jay McCrum had brought them the plans of the building, and so they were able to concentrate significant efforts on the portion of the factory where the ammonia was kept. They also were able to move some propane tanks out of harm’s way and pop the relief valves on other tanks so that the propane could burn off.

“If they’re burning off, they can’t explode,” Rowley said. “There was no pressure building up. The only ones who would have been in danger were the firefighters.”

Although unexpected, the firefighters were prepared for this type of scenario, Rowley said.

“We actually did a big field exercise down there [at Penobscot McCrum]. It was mostly for ammonia release,” he said. “Our worst-case scenario was for the [ammonia] tank to completely rupture all at once.”

Ammonia, which has a distinct, pungent odor, is highly toxic and an inhalation hazard. At extremely high concentrations, it can be fatal. Such high concentrations likely wouldn’t happen, even if the tanks had ruptured, Rowley said, because the ammonia would have dissipated fairly quickly in the fresh air. It’s not highly flammable, but containers of it may explode when exposed to high temperatures.

Still, an ammonia release could have caused distress to humans, depending on where the winds were blowing, he said.

“Probably not enough to kill anybody. But it could have sent some folks to the hospital,” he said.  

That didn’t happen either. A shelter in place was quickly ordered.

Still, it seemed better to some officials to have students at Belfast Area High School — located less than a mile from the burning factory — keep a safe distance from school. At 7:38 a.m., just after students began to arrive at school for the day, an alert was sent to parents telling them that the high school needed to evacuate and that bus drivers would bring the students home. Other district schools would have a two-hour delay.

But Mary Alice McLean, the superintendent of RSU 71, said it wasn’t long before administrators heard something ominous that changed the plan.

“When we learned about the possibility of toxic fumes, and that the bus garage was in the line of fire, it became apparent that we had to cancel everything,” she said.

The lack of transportation was the deciding factor, and all schools were canceled at 8:02 a.m.

That left Troy Howard Middle School available for those who couldn’t stay where they were. Residents from Harbor Hill began arriving at the middle school just before 8 a.m., according to McLean.

During the evacuation, residents gathered in the middle school gymnasium, where breakfast food and games were quickly made available to them.

The morning was “a little chaotic,” according to Doug MacWilliams, 64, who originally is from Thomaston. He heard about the fire on the news, and when he learned Harbor Hill would be evacuated, he immediately headed out the door.

“I was kind of shocked,” he said. “I just did what I was asked to do. I didn’t question anything … as far as I know, we’ll be here until it is safe for us to go back to our facility.”

But even before all the residents had been evacuated, the facility received word that it was safe to return.

“The health and safety of our patients and residents is always our number one priority,” Mayer said.

Rowley said that in the coming days, he hopes to be able to sit down with other officials and go over what happened Thursday. Something on his mind is that some people evacuated their homes, businesses and facilities, including Harbor Hill, even though that is not what was advised.  

“The best thing you can do for ammonia is shelter in place,” he said. “You’ll be perfectly fine inside your house. It will act like a protective suit.”

In the end, the long day of firefighting and emergency decisions will hopefully lead to a better understanding of how local systems work, and how they can be improved, he said.

“It doesn’t matter how good or how bad the incident goes,” Rowley said. “There’s always something that can be learned.”