WOLFF luffing cranes in operation at a hydroelectric
The Valais Alps is home to one of the most powerful pumped storage power plants in Europe. The current underground facility uses the downward slope between the existing reservoirs of Vieux Emosson (2,205 m above sea level) and Emosson (1,930 m above sea level) to generate energy. One of the objectives of the project is to double the storage volume of the higher reservoir, Vieux Emosson, which means that the height of the dam has to be increased. The responsible contracting companies, Groupement Marti Implenia (GMI), commissioned premium manufacturer WOLFFKRAN with this job, who had already been involved in the construction of the original dam wall of the Vieux Emosson in the 50s. The new challenges on the high alpine construction site are now being tackled by the luffing cranes Big WOLFF 1250 B and WOLFF 500 B.
Work already began in 2008 with the expansion of the access tunnels and the development of the construction sites. The WOLFF 1250 B came into operation in the spring of 2012 for the demolition work on the crest of the wall. The WOLFF 500 B was put to use last year with the start of the concreting work to extend the height of the wall. By fall of 2014, the wall will be increased by 21.5 m to a final height of 65 m. As a result the storage volume of the Vieux Emosson will be doubled to 25 million m3.
High load capacities required for the demolition work
Impressive assembly concept
WOLFFKRAN stands head and shoulders above the competition with its sophisticated assembly concept," says Christian Maillet, site manager at GMI. "Due to their long jibs, the tower heights of the luffing cranes, at 30 and 45 m, could be selected significantly lower than would have been possible with a saddle jib crane. This meant that both WOLFFs could be erected to end height with a mobile crane and did not have to be climbed afterwards," explains Maillet. "Assembling tower cranes at this level represents a major challenge," says Philippe Gremaud, area manager at WOLFFKRAN. "Heavy snowfall and severe cold weather added further complications to the assembly. But we were able to draw on our experience with such complex assembly conditions, and managed to erect the 1250 B in seven days and the 500 B in just three."
Ideal when space is limited
The WOLFFs are in hibernation, so to speak, since November 2013, because work cannot proceed at these altitudes due to the large amount of snow and high wind speeds. To avoid any danger, the jibs of the two cranes were dismantled and stored safely. The red giants will be able to resume their work in the spring. To complete the dam, they will be on higher towers of 50 and 60 m respectively.
New energy for Switzerland
© InfraStructures - Tous droits réservés - All rights reserved