BONNER - For 34 winters, the buzz and roar of the immense indoor plywood plant at Bonner defined a culture, a lifestyle and even its own climate on the banks of the Blackfoot River.
For the past three winters, the 11-acre building sat empty after Stimson Lumber Co. shut it down.
Late last week, nearly a third of it went tumbling down, a victim of this winter's exceptional snowfall. There was no one and nothing inside when the roof fell, said Jeff Webber, Stimson's vice president of manufacturing in Portland, Ore.
"We had a pretty big snow load and it kicked a portion of the plant down," Webber said. "The building's almost 500,000 square feet and we lost 140,000 square feet of the roof, which is a pretty good chunk."
Witnesses at nearby Bonner School heard a loud crack late Thursday morning, the first of at least two collapses. A broken water line began spewing water into the air.
"I was driving through Milltown when I saw a huge brown cloud billowing up over the buildings," said Chuck Erickson, who lives in the area. "At first I thought it was smoke, but the closer I got I realized it was sawdust."
When the dust cleared, Erickson said, "you could see that the roof was gone and a fire main was spewing water into the big hole."
The plant, built by Champion International's U.S. Plywood in 1973, is under a series of five long rounded roofs. The two longest extensions are - or were - some 1,400 feet long. When it was built, the half-million square feet of floor space made it the largest plywood plant in North America.
"There were people who had worked there 20 years and had never been on the other end," Otis Seal, the long-time maintenance supervisor of the plywood plant, said Tuesday.
Champion sold to Stimson in 1993. Stimson closed down the plywood plant in July 2007 and the rest of its operations in Bonner the following year. The mill has been up for sale ever since.
Webber said Thursday's initial collapse came above what used to be the dryer, glue room and presses, which occupied most of the southwestern-most section of the plant.
"It's different without a heat load in there," he said. "Above the dryers and the presses there would never be any snows accumulating because there was so much heat in the building with it operating."
Webber said there had been some snow removal operations prior to the collapse.
The lone business, Northwest Paint Inc., leased space last year in the side of the plant closest to the Blackfoot River. It was not damaged.
By Tuesday, work crews and heavy equipment were busy assessing the damage, tearing down compromised sections of the plant, and cleaning up the mess.
"We haven't decided what we're going to put back," Webber said. "As you know, we have the property for sale, and our intention is to make it as attractive a property as possible for sale."
The plywood plant and the rest of the former Stimson mill site - some 173 acres - is priced at $16 million, according to the website of C.B. Richard Ellis, the Washington-based real estate firm that's selling the mill for Stimson.
"Those buildings were kind of a selling feature for that property," observed Erickson, who serves on two boards in the Bonner-Milltown community. "They were already there, and it was pretty unlimited potential as to what could go into them. That's a big loss for Stimson - and the community really."
Meanwhile, a cleanup operation that has grown in scope continues upstream from the plywood plant. Envirocon is nearing the end of the removal of a PCB-contaminated cooling pond in the Blackfoot River, but more poisoned soil was discovered last fall adjacent to the pond under the old stud mill.
Keith Large, project officer for the Montana Department of Environmental Quality, estimated 20-25 of the total volume remains to be cleaned up. Stimson hasn't finalized a plan to retrieve it, but Large said it looks like the stud mill, already empty and deteriorating, will have to be dismantled to get at it.
Large said that there is no known contamination on the plywood plant end.
"It seemed like that end of the property was shaping up for something that could take off in the future," he said. "It's not clean enough for residential use, but for manufacturing property it seems to be in pretty good shape."