In December 2000, the steel tunnel lining of Cleuson Dixence burst. After detailed investigations to discover the cause of the damage, a general rehabilitation concept was designed, and in 2003 Energie Ouest Suisse and Grande Dixence founded Cleuson Dixence Construction to conduct the rehabilitation.
In the course of the rehabilitation the entire pressure tunnel will be provided with an additional steel lining on a length of 4km, at a total weight of 12,600 tons. The design pressure of 200 bar is presently the highest design pressure for a penstock of a hydro power plant worldwide. In order to secure the high quality requirements of the new steel lining an extensive qualification programme for the material and the weldings is to be accomplished before the start of manufacture.
Erection works for the contract will commence in mid 2007, with start-up of commercial operation planned for the end of 2009.
