The HEW power plant was scheduled to have both its chimney and the boiler houses (seen on either side of the chimney) demolished. Fire crews sprayed the ground to dampen it in advance in an attempt to keep the dust under some control.
It can can take as little as a day to ready a chimney for demolition; but large buildings have taken as long as 6 months to prepare, with all non-load bearing walls removed and critical areas wrapped in fencing or cloth material.
Before we go on, we should note that the word that is used for this process, ‘implosion’, is a bit of a mis-characterization. The demolitionists aren’t blowing up the structure but rather using explosive charges in such a way that gravity itself brings the structure down.
In 1996, Stacy Loizeaux of demolition specialists NOVA, said: “The term “implosion” was coined by my grandmother back in, I guess, the ’60s. It’s a more descriptive way to explain what we do than “explosion.” There are a series of small explosions, but the building itself isn’t erupting outward. It’s actually being pulled in on top of itself. What we’re really doing is removing specific support columns within the structure and then cajoling the building in one direction or another, or straight down.”
In this case, the preparations to bring down HEW’s 15,000 tons of concrete included 300 kg of the explosive ‘gelamon’, 1,300 detonators, and 400 meters of ignition cord. You can see the beginning of the blast exploding dust and smoke sideways from the critical points.
There were three tiers of explosions, with the top two designed to separate or snap the chimney at those locations. The demolitionists had already bored holes into the smokestack and wrapped the top section in such a way that the pressure would make the chimney fall in the desired direction.
“With a plume of smoke appearing to escape from its flue, this falling stack seems to be exhaling its last breath as it crumples to earth,” says Chimney Liner Pro in an article on chimney demolitions. Actually, of course, it is a burst of soot that rose upwards due to the air pressure.
Building implosions are used because they can reduce a building or other structure to rubble in seconds when other means may take months. Just imagine using a crane at the top of a chimney to dismantle it manually. Using this slower method, there is also the danger that the structure itself becomes so unstable that it comes down, doing damage to surrounding buildings and harming people.
As noted, to demolish chimneys like this one, many small explosives are used throughout the chimney in critical support areas to weaken the structure. Once these supports have been removed, the collapse begins.
As you can see in this picture, the chimney is not falling completely in on itself – which might have been hard given its narrow footprint – but falling at an angle such that it misses the nearby building. Only a few explosives experts in the world will try a demolition where the structure falls right into its own footprint.
With an immense boom and emitting a cloud of dust, the chimney finally collapses in its own rubble. These images make the implosion seem slower than it actually was. Such demolition events take place at immense speed; seconds are all they take. Two hundred and fifty-six meters of smokestack taken down with no injuries.
The HEW-Kraftwerks implosion didn’t go quite without incident, though. As the chimney completed its fall, debris scattered and there was a loud crack as well as a burst of light from the power station next door.
Chimney Liner Pro describes the cause as this occurrence: “The massive force of the blast blew off the ventilation grill from one of the boiler houses, which flew into an adjacent building, causing a short circuit and a consequent blackout in parts of the city plus an emergency shutdown and loss of production for several days in nearby oil refineries.”
Most implosions happen with nothing more than perhaps a broken window nearby, but accidents can happen that actually injure people or cause the death of those nearby.
Yet, despite a certain level or risk, the power of implosions has made them spectator events when they do occur. You can see people in the background here, and as many 50,000 have attended other such implosions.