October 1, 2012 by David Godkin
It’s a moment Ryan Priestly dreads every time he does a job like this. Peering down through the windshield of his high reach excavator, carefully leaning into the controls and inching the collapsed concrete slab below him upward—the sight of a pant leg or a dress comes into view. It almost always ends this way and is something the owner of Priestly Demolition Inc. of Kettleby, Ont. says demolition equipment operators never get used to.
“That’s the part that sticks out, when you actually find somebody. It gives you a lot of respect for the people who do it all the time like the fire department and the police department. But you know it’s tough for everybody.”
Here in Elliot Lake, people are still traumatized by the collapse of the Algo Centre Mall roof parking lot on June 23 of this year, which left two mall employees dead. After receiving the emergency call at 1:45 a.m. that morning, Priestly’s crews spent 15 hours hauling a 90-tonne demolition excavator—piece by piece—up the TransCanada Highway to the collapse site. For the next 30 hours, fuelled mostly by adrenalin and the thought of someone alive beneath the wreckage, Priestly applied everything he knew about collapsed buildings, a task complicated by the fact that this collapse hadn’t happened at the edge of the building.
“It happened inward of the building. And of course it wasn’t just the building that collapsed; it was a parking garage, so the problem is the slabs of the parking garage were big thick concrete. And then we had to lift these precast concrete slabs off the people in the collapsed area.”
Priestly’s first task, once the excavator’s counter weight and boom were assembled and hydraulic shear attached, was to tear down a section of building approximately 80-ft. high by 90-ft. long and 30-ft. wide outside the collapse. At the very centre of the collapse, an area about 60 ft. by 30 ft., the real work began; delicately lifting each slab and piece of debris. Priestly said his crew couldn’t just go in there and start ripping it apart. He had the voice of the search and rescue expert crackling in his head phones.
“‘You keep moving, but trying to keep moving at a safe pace. There’s members of the police and fire rescue teams all around you so the last thing you want to do is have an accident.’”
Concern about safety naturally extends to his own crews whether at Elliot Lake or in the scores of heavy industrial projects at mine sites, paper mills, car, steel and cement plants that Priestly Demolition has taken on. Engineer-stamped demolition plans, proper equipment maintenance and training all play a role in keeping people safe in demolition. The key, says Priestly, is showing every structure immense respect.
“Don’t get greedy. Otherwise you can bite off more than you can chew and the next thing you know you have an uncontrolled collapse.”
Preparation is everything…
Richard Wayper doesn’t pull his punches. “Planning, the up-front piece [in any demolition] is a very delicate balance and it’s usually the reason why projects are wildly successful or wildly unsuccessful,” says the vice-president of Northwest Demolition and Dismantling of Tigard, Ore.
Wayper has overseen demolition and environmental cleanup on high-risk sites such as: chemical and chemical weapons facilities; nuclear power plants and airport control towers in Canada and the U.S. He says a common mistake owners make is not involving everyone—engineers, site supervisors, local contractors—in early stage planning, i.e. long before a high reach excavator takes its first bite out of a plant building or bridge.
“Six months later you find out that if you’d had the people around the table who actually do demolition every day for a living they’d be able to say, ‘You know what, we can’t do that because there’s a big bin of hazardous waste in the corner’…The best run projects are the ones where there’s a suitable amount of planning up front,” says Wayper.
In February, Northwest Demolition began taking down an aluminum smelter in Kitimat, B.C.—Rio Tinto plans to replace it later this year with a new state-of-the-art smelter. “[It is] a very significant project,” says Wayper.
It will employ a fleet of excavators fitted with a variety of shears, hammers, grapples and buckets to demolish the elevated bulk conveyors as well as thousands of tonnes of concrete and structural steel within 50 different buildings (some of them 120-ft. high).
“It’s a big structure, a complex project, with a close to $3-billion capital project coming right on its heels,” adds Wayper. “So it’s a very aggressive schedule.”
One piece of equipment that has historically been used to meet aggressive demolition schedules is the wrecking ball. And while Wayper says the rumoured death of the wrecking ball is grossly exaggerated (his company continues to use them on high buildings), another approach to demolition is fast disappearing. Companies are less inclined to undermine a building at its base because of how tricky it is to control the manner and direction in which it falls.
“There have been several recent fatalities in our industry and they’ve been predominantly through people undermining buildings and having them behave in an unexpected way,” he says.
Instead, demolition firms prefer demolishing a building from the top down, in smaller manageable pieces, says Wayper. His company also spends a lot of time and effort ensuring its people have the right skill sets to operate the high reach excavators necessary for this work. “You’ve got this big lever up in the air and it doesn’t take a lot for them to fall over, but if handled correctly they really improve the safety on a project,” he says.
You supplement good operator skills by making sure the equipment you purchase has the necessary power and safety built in, Wayper adds.
It’s never “smash and dash”…
Pulling down a four-storey department store may not be as dramatic as the rescue operation in Elliot Lake or tackling a nuclear power plant, but commercial demolition comes with its own sets of problems. Particular care must be taken to protect the public from falling debris and dust for one thing. For another, no one wants a 90-tonne demolition excavator punching holes in their wall in the middle of a business day. It’s a scenario that is particularly worrisome to commercial mall owners with a bevy of businesses to protect.
A case in point: Charlottetown’s Holman Department Store built in 1924 and demolished in 2009 to make way for the new 10-storey Holman Grand Hotel. Richard McGuigan calls the demolition a “strategic” job that required his company, Bulldog Demolition, to very precisely “unhook” the older building from the adjacent mall structures,notably the Bank of Nova Scotia building. The problem, McGuigan says, started with the original building methods for the mall.
“In those days, all they did was put some trusses across into the brick that belonged to the guy next door and then put another wall on the next one—and in one case, they didn’t even do that: they just put studs across from one building to the other.”
In this instance, Bulldog cut away the store’s walls from the buildings surrounding it. On jobs like this McGuigan is also careful to position spotters at the perimeter to watch for any sign that the wall is falling outward instead of inward and for any unexpected movement of adjoining walls. It’s a tricky job, in tight quarters, requiring enormous precision and patience on the part of the equipment operator.
It’s because commercial demolition operators work in such small spaces that many advocate the use of equipment with zero-tail swing. One of them is Jamie Wright, product manager for Terex. He says zero-tail swing machines cause less damage to both the peripheral structures and the machine, because the machine’s movements are contained within its tracks.
“With tighter, more-restrictive housing developments preventing the use of traditional compact excavators, the zero-tail swing models work well with contractors’ other equipment for more productive overall job site performance,” says Wright.
Tom Connor is not so sure. The product specialist for Bobcat questions whether the access you gain employing zero-tail swing excavators is worth the lift capacity you give up. He also says many manufacturers claim their new machines have zero tail swing, when in fact, up to five inches of tail swing are plainly visible. It’s a distinction, Connor says is not fully understood or appreciated by all customers.“Most of them are not zero tail swing, especially when you get into these four- and five-tonne machines. The majority are minimal or compact tail swing.”
Every bit as important as the machines you use on a job site is job site clean-up, something Wayper tells us is not done indiscriminately. Gone are the days when what remained of a demolished building ended up in a landfill. “More and more today the emphasis both environmentally and commercially is separating the G-rock from the piping and the steel from the concrete for re-use later on,” he says.
Not the most exciting part of demolition, Priestly agrees, but necessary and lucrative.
“You go to one of our demolition sites and it’s like a mini-scrap yard or mini-concrete recycling yard. It’s a very important part of the job.”
However you cut it, everyone agrees that operating a demolition business today is a multi-faceted proposition, from the salvage provisions built into your demolition contract to the power and access capacity of your machines. And the truth is, says Priestly, we often learn as much from taking structures down as we do putting them up.
David Godkin is a B.C.-based freelance writer. Send comments to firstname.lastname@example.org.