The Valais is rich in hydropower. But the existing lines will not have sufficient capacity to transport all of this energy once the Nant de Drance pumped storage power plant starts operation. A new 380 kilovolt line is required.
Construction of a new 30 km overhead line between Chamoson and Chippis built on the hillside on the left bank of the Rhône. Four voltages are combined on the same line: 380 kV, 220 kV, 65 kV (between Chamoson and Aproz) and 132 kV CFF (between Chamoson and St-Léonard). Removal of nearly 89 kilometers of line on the Rhône valley floor.
The new overhead line between Chamoson and Chippis is absolutely necessary. It serves not only to connect the large Valais hydroelectric plants, but also it links Valais to the Swiss and European UHV grids.
As early as 1986, the former EOS, which later became Alpiq, announced its intention to build a UHV line linking Romanel to Chippis in three sections including Chamoson-Chippis. In January 1997, a public enquiry into a first project was undertaken by the Federal Inspectorate for Heavy Current Installations (ESTI). This project, having prompted numerous complaints as well as negative initial assessments from certain federal and cantonal authorities, was suspended and then restarted with the agreement of ESTI at the stage of a detailed project without the need for a preliminary study.
In June of 2002, Alpiq presented a new project and submitted an approval request for technical plans to ESTI, followed by a second request in 2006 to cover changes requested during the approval process, which specify the construction of a 380-kV line between Chamoson and Chippis and, amongst other things, combining the lines of the Force Motrices Valaisannes (FMV) and SBB on the same tower support. On 11 June 2007, ESTI forwarded the file to the Swiss Federal Office of Energy (SFOE) for the next steps of the authorization process.
In June of 2010, the SFOE approved the plans submitted by Alpiq in 2002 along with the changes that were later requested, and authorized Alpiq to build the section between Chamoson and Chippis in the form of an overhead line. Many appeals were then filed with the Federal Administrative Court (FAC), and then with the Federal Tribunal, which confirmed the urgency of the line, of the overhead line corridor, and the request of the FAC to study the possibility of further reducing nuisance noise from the 380 kV line.
On 19 January 2015, the SFOE granted permission to build the line. The Swiss Federal Administrative Court rejected the appeal in December 2016. With its ruling on 1st September 2017, the Federal Court has provided ultimate confirmation of the Swiss Federal Office of Energy's planning approval decision made on 19 January 2015. The construction work on the overhead line between Chamoson and Chippis in the canton of Wallis began. The line was put into service on 30 September 2022.
The commissioning of the new line does not mean the end of the project. The construction permit for the line requires Swissgrid to dismantle 322 pylons and 90 km of existing overhead lines on the Rhône plain. Priority will be given to the dismantling of the old 220 kV Chamoson – Chippis line, which crosses a number of residential areas. Dismantling work will begin in 2023 and is expected to be completed by 2027.
| Length | 30 km of line corridor with 77 metal pylons |
| Height of the pylons | between 60 and 90 m, four pylons between 90 and 100 m |
| Lines | 2 x 380 kV 1 x 220 kV 1 x 65 kV 2 x 132 kV |
Substation Chandoline
Swissgrid has built a new 220 kV substation at Chandoline to feed two 220/125 kV transformers belonging to Grande Dixence SA. These facilities were commissioned and connected to the existing Chamoson-Chippis 220 kV overhead line in June 2017. The substation will subsequently be connected to the Chamoson-Chippis 380/220 kV overhead line after it is commissioned. The Chandoline substation ensures supply security for the pumped power facilities operated by Grande Dixence SA in Arolla and Ferpècle.
The connection to the substation implied the construction of two pylons supporting two 220 kV lines.
Almost 90 km of overhead lines will be removed once the future Chamoson–Chippis overhead line is brought into service, allowing the removal of 322 masts and pylons in the Rhone valley and freeing up the villages through which these lines currently pass. A specification in the building permit issued by the Swiss Federal Office of Energy in 2010 requires Swissgrid to dismantle these lines following the commissioning of the new line. Once they are dismantled, there will be 60 km less of electrical overhead lines between Sierre and Martigny.
Once the existing 220 kV line is dismantled, the Poutafontanna nature reserve will be entirely free of electrical lines.
At the request of the Federal Administrative Court, Swissgrid has suggested measures to reduce sound pollution using the latest technology. The installation of three bundled conductors (cables) with a diameter exceeding the initial plan for the 380 kV line will allow sound pollution to be reduced. The noise emitted by the 380 kV overhead line will be less than that of the initial plan and below the federal limits set in this connection.
The future Chamoson–Chippis overhead line is in compliance with the Federal Ordinance on Protection against Non-Ionising Radiation, and the limit of one microtesla will be respected throughout the transmission route in sensitive utilisation locations:
