Airborne demolition

The chimney at VFI in Wels is a hundred years old. Until now it has been needed to heat the machine halls. Now that the premises have been fitted with a gas supply, the anticipated transition from crude oil to natural gas is able to take place. According to company management, this will make production with far lower emissions possible. The chimney, visible from miles around, had to give way. But how? Detonation was not possible due to the space constraints. The company also didn’t want to bother its neighbours with the resulting dust pollutants.

Adventurous solution
The Felbermayr team found a solution using a seemingly adventurous method: »We thought about lifting the excavator while suspended from a crane hook, and then demolishing the chimney from the top down,« said site manager Bernhard Radler as he talked about the procedure, which was later carried out using a modified lifting plateau. However, before this, they had to convince the TÜV about the unorthodox procedure between sky and earth. No mean feat if you remember how the main aim of this organisation is to promote technical safety! »Our TÜV contact was very cooperative, « remarks Radler about the co-operation, which did have a positive outcome. It was even possible to agree on a practical solution taking all the safety-relevant issues into account.

Suction excavator on hand
However, before the demolition work could be started, the inside of the chimney had to be cleared of soot. »This was necessary in order to prevent the demolition material from mixing with contaminated substances. Otherwise, the debris could not have been recycled,« reports Radler. To extract this material, the suction excavator from the Felbermayr Waste Management division was used. With an operating pressure of up to eight bars, the excavator extracted the soot from the inside wall of the over 100-year old chimney in just a few hours. Using this method, around twenty cubic metres of contaminated material was removed, which was later analysed and disposed of correctly.

Safety first
The employees also played it safe when protecting the surrounding properties. Their roofs were reinforced with beams and ceiling supports and covered with layers of building fleece and bales of straw to shield against splinters. After these measures were approved by the construction co-ordinator, the actual demolition work could begin with mobile cranes and excavators. »If the excavator operator had not turned up, I would have had to get in myself,« says the foreman with a trace of humour as he concentrates on observing the lifting of the excavator. Suspended from the hook and fixed to the chimney with two I-supports, the excavator operator began the demolition work. An employee remarked how it is normally safer up than down during demolitions. But everyone was sure of one thing: this was no normal job and the operator had everyone’s utmost respect. By late afternoon, the chimney had been demolished to a height of eight metres, and the excavator had been let down from its mission above the rooftops of Wels. The remains of the chimney were removed from the ground up with demolition equipment. »Even if it is not as safe, I prefer it,« says the excavator operator, smiling to himself, pleased to have his feet firmly on solid ground again.

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