PenPly stack postmortem: 'Remember: Blasting is not a spectator sport'
PenPly stack bluff cam -- A view of the abortive attempt to topple the smokestack with explosives at the former Peninsula Plywood mill in Port Angeles, Wash., on April 8, 2013. Videography by Dave Logan for the Peninsula Daily News
Keith Thorpe/Peninsula Daily News
The remains of the Peninsula Plywood smokestack lie in wreckage Tuesday after it was taken down with a combination of explosives and brute force Monday evening in Port Angeles.
By Jeremy Schwartz
Peninsula Daily News
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Case in point: The concrete at the base of the Peninsula Plywood smokestack, after being weakened with carefully placed explosive charges, was supposed to collapse in a certain way, sending the 72-year-old stack to its ruin on the site of the former mill at 3:30 p.m. Monday.
The charges, laid by Woodland-based Wallace Technical Blasting Inc., went off as expected, company owner Jerry Wallace said, though the first blast did not weaken the concrete in the direction that was planned.
That kept the stack from collapsing on time.
Instead, the stack fell to the ground on the now-leveled mill site with a chest-thumping thud at 6:13 p.m., 2 hours and 43 minutes after the explosive charges planted at the base of the structure went off.
Wallace said the placement of the charges was based on a standard design he's used on the demolition of similar stacks, such as those that once towered over a former Georgia-Pacific-run paper plant in Bellingham.
He added that such design “rules of thumb” do not always work as expected.
“Had we put the hole where [this] design said we didn't need one, it would have come right down,” Wallace said Tuesday.
The force behind the charges was not the issue, Wallace said.
He estimated that concrete chunks would have flown twice as far as the nearest onlookers had protective rubber mats not been placed at the base of the stack.
“There's no doubt we had plenty of power to make the concrete fly,” Wallace said.
Thousands of onlookers had flocked to bluffs overlooking the site to watch the stack fall at the appointed time.
Many ended their vigils early as minutes of waiting for the stack to topple turned into hours.
Wallace admitted the stack withstanding the blast was embarrassing but said demolitions don't always live up to expectations.
“The spectators were probably pretty unhappy,” Wallace said.
“But one of the first blasting instructors I ever had [told me], 'Remember: Blasting is not a spectator sport.'”
All that remains of the stack is shattered concrete chunks, broken brick and splintered fiberglass, the latter two of which must still be tested for potentially toxic dioxins before the debris is removed.
Chris Hartman, the director of engineering for the Port of Port Angeles, which owns the 19-acre site, said the test results should be in Thursday.
The tests for dioxins, potentially toxic compounds typically left over from industrial processes, in the concrete outer casing of the stack came back clean, Hartman said, though demolition crews with Rhine Demolition LLC will wait to remove all the debris until the other test results are delivered.
“They'll cover it up and wait until we get the test results back,” Hartman said Tuesday.
Hartman said any such substances would have been contained within the structure of the stack and not spread by its demolition.
How Rhine disposes of the debris depends on whether dioxins are found in the brick or fiberglass, Hartman said.
Once removal work begins, Hartman said, Rhine crews should not take more than a week to haul all the material off-site.
The demolition work, which Rhine is completing under a $1.6 million contract with the Port of Port Angeles, is expected to be done by May 3.
After the explosions did not take down the stack as planned Monday, crews moved in to survey what had happened and determined the reinforced steel running up and down the structure needed to be cut.
Crews then began shearing into the steel with cutting torches and massive electrical saws as a steel cable running from the stack to a nearby excavator was pulled taut, Hartman said.
Once enough steel was cut, a 70-ton jack donated by local contractor Hermann Bros. Logging and Construction was wedged into the hole blown into the south side of the stack and used to lift the structure to the north until it fell, Hartman said.
“The hydraulic jack was the straw that broke the stack's back,” Hartman said.
Despite the delay, Hartman said, port officials and the contractors on the demolition are glad the stack fell safely and where it was supposed to.
Last modified: April 09. 2013 6:43PM