After proceedings ended with the dismissal of appeals by the Federal Court on 1 September 2017, preparatory field work for the construction of the 380-kilovolt (kV) Chamoson – Chippis line will begin in January 2018. Swissgrid will begin the construction of the pylons in August 2018.
The new 29.2 km long, 380 kV overhead lines will link the Chamoson and Chippis substations. The line has been divided into five sections in order to complete the work as quickly as possible and to optimise the construction plan as much as possible:
- Section 1 - municipalities of Chalais, Chippis and Sierre
- Section 2 - municipalities of Sion and Vex
- Section 3 - municipalities of Sion and Grône
- Section 4 - municipalities of Nendaz and Sion
- Section 5 - municipalities of Chamoson, Ardon, Vétroz, Conthey and Sion.
Site layout surveys and forestry work will be carried out on sections 1 and 2 in January 2018. Construction of the line in these sections will begin in August 2018. In addition, geotechnical investigations will be carried out on section 4 during 2018. The construction of sections 3, 4 and 5 will begin in 2019. The construction of this type of power line generally takes two to three years.
Removal of 90 kilometres of overhead lines
The commissioning of the 380 kV Chamoson – Chippis overhead line will prompt the removal of nearly 90 kilometres of overhead lines and 322 pylons in the Rhone valley. A specification in the building permit issued by the Swiss Federal Office of Energy in 2010 requires Swissgrid to dismantle this 90 km of power lines immediately following the commissioning of the new line.
The completion of the Chamoson – Chippis 380 kV overhead line is essential for the transmission of energy produced by the Valais power plants – in particular the pumped-storage power station Nant de Drance – to the consumption centres in the Lake Geneva region and on the Swiss plateau. It will eliminate one of the biggest congestion points of the Swiss electricity transmission network. The modernisation of the transmission network is a key factor in moving towards the sustainable energy future required by the Confederation and the Swiss people through the Energy Strategy 2050. Other projects to reinforce and extend the extra-high-voltage grid in the Canton of Valais are in the pipeline, notably the voltage increase of the Chippis – Bickigen overhead line from 220 kV to 380 kV, as well as the Chippis – Mörel and Mörel – Ulrichen lines (Gommerleitung).
Initiative of the State Council of the Canton of Valais
In November 2018 the State Council of the Canton of Valais has taken the initiative of carrying out further analyses in order to investigate the feasibility of burying a part of the extra-high-voltage line along the transmission line between Chamoson and Ulrichen. A steering committee has been installed to draft an agreement in principle. Swissgrid will participate to provide its technical expertise for the studies, while at the same time building the new 380-kilovolt (kV) Chamoson – Chippis overhead line.