Decommissioning of the wind farm in Fleetmark: What happens to the foundations
The tower, nacelle and rotor blades have already been dismantled and disposed of – now the foundation underneath must also be removed. Each of the eleven old wind turbines in the Fleetmark wind farm stood on a massive concrete block measuring 13.5 x 13.5 metres and weighing around 640 tonnes. These foundations are now being dismantled one by one. In civil engineering jargon, this is called “demolition”.
Two excavators are being used for the job, one of them fitted with a large chisel. It takes three to four days to remove the last remaining reinforced concrete from the 2.5-metre-deep base. The foundation pit is then properly filled in with earth and restored to its original condition in line with the local soil management requirements.
Recycling during repowering in the Fleetmark wind farm
Prokon is using the broken concrete from the old installations to expand the access roads to the new wind turbines. The entire road network in the Fleetmark wind farm covers just over 6.5 kilometres. Many sections have to be newly laid and widened so that construction vehicles, including large heavy-load transporters, have enough space.
“For this purpose, we can recycle the rubble close to the site and at the same time avoid long transport routes to landfill sites,” says June Lim, construction manager for project development at Prokon. Strict legal requirements also apply to the second use: “Samples of the concrete residues were first sent to a laboratory for pollutant analysis in order to guarantee environmental compatibility,” Lim says.
New foundations for more powerful wind turbines
In parallel, the first excavation pits for the repowering are already being dug. As the eight new wind turbines, at around 170 metres high, are significantly larger and heavier, they also require larger foundations. The circular bases have a diameter of 27.5 metres. Including excavation, filling and curing, it takes a good five to six weeks before they are complete.
After that, tower construction for the new installation can begin. The concrete is delivered from a nearby ready-mix concrete plant. The new foundations meet all environmental standards and can later also be recycled.
For now, though, the eight new, significantly more powerful wind turbines will produce clean electricity from windy heights for at least 25 years – and three times as much as the eleven old turbines.
