Existing 380 kV overhead line Pradella – La Punt

Grid project Pradella – La Punt

The Pradella - La Punt line is essential for the transit of electricity and the security of supply in the canton of the Grisons. To enable the energy from hydropower to be transported in full, the route between Pradella and La Punt, which spans some 50 kilometres, needs to be extended along its full length to two 380 kV lines. Swissgrid began construction in 2017. Commissioning is planned for 2022.

Your contact for this grid project

Joshu Jullier
Joshu Jullier

Phone +41 58 580 21 11
info@swissgrid.ch

380 kV line
380 kV line
Dismantling
Dismantling
Existing line
Existing line
Substation
Substation

Overview

The existing extra high-voltage line between Pradella and La Punt represents a bottleneck in the Swiss and European transmission grid. The expansion of the route to two continuous 380-kV lines will increase the import capacity from the north, strengthen the connection with the international grid (Austria, Italy) and improve the transportation of energy from hydropower in the canton of the Grisons. The project will also improve security of supply.

Improvement upon the current situation

  • Elimination of the structural bottleneck between Pradella and La Punt so that more electricity can be transported
  • Improvement of the transport of energy from hydropower in the canton of the Grisons
  • Strengthening of the connection to the international grid towards Austria and Italy
  • Increased reliability in supply of electricity to the Engadin
  • Reduction in transmission losses as well as electromagnetic fields and noise generation through the expansion to two 380-kV lines along the entire route and the use of double or triple conductors.

Project

Normally, a pylon is fitted with one cable on each side. Between La Punt and Zernez, however, the pylons are currently only fitted with one line on one side. The reason for this is that transport requirements were lower when the line was built in the 1960s. Swissgrid is now adding a second 380 kV line to the entire 50 km route between Pradella and La Punt. In future, the pylons will therefore carry one line on each side. This will have a positive effect on emissions as it will be possible to operate the line in such a way that the electric and magnetic fields of the two lines cancel each other out partially, thus reducing overall emissions.

Between La Punt and Zernez, the pylons currently carry a line on only one side.
Between La Punt and Zernez, the pylons currently carry a line on only one side.

Facts and figures

Length of line 50 km
Number of pylons 127
Height of the pylons Between 50 and 80 m
Lines Two 380 kV lines

Dismantling of 1,100 pylons due to the fact that the 110 kV line is being laid underground

As an alternative measure for the Pradella – La Punt grid project, Engadiner Kraftwerke (EKW) is replacing the 60 kV overhead line between Pradella and Bever with a 110 kV underground cable. This new line will be used to transport power from the Ova Spin power plant. The first section between Pradella and Zernez was put into operation in summer 2019. The second section between Zernez and Bever was completed at the end of 2019, while the dismantling of the 1,100 pylons has already started and is expected to be completed by mid-2021. This will significantly improve the natural scenery. The project will also enable the cabling of the 16 kV line and the hook-up of the municipalities to the broadband Internet.

Construction of the 110 kV earth cable between Bever and Pradella (video of Brugg Cables, in German)
Construction of the 110 kV earth cable between Bever and Pradella (video of Brugg Cables, in German)

Comparison with an underground cable solution

The planned project approach was compared with the use of a new 380-kilovolt underground cable over the length of both the whole route and the four sections. The comparison was made in accordance with the assessment scheme for transmission lines set out by the Swiss Federal Office of Energy (SFOE). The comparison indicated that the additional costs for full or partial underground cabling were disproportionately high and only partially lessened the impact on the landscape.

Project history

The Pradella – La Punt project was launched in the 1990s with a preliminary environmental impact assessment (EIA) process. In January 2000, the planning work was suspended as a result of the impending market liberalisation, the delays in cross-border line construction projects and the requirements arising from the preliminary EIA process.

In 2007, the project work was restarted with the development of the detailed project and the report on the environmental impact. A year later, the SPTL check, based on the Sectoral Plan for Transmission Lines (SPTL), was carried out at the request of the Swiss Federal Office of Energy (SFOE), the responsible planning authority. In December 2008, the SFOE decreed that, on the basis of the SPTL check already carried out, it was not necessary to conduct an SPTL process. However, an EIA check did have to be carried out.

In 2009 and 2010, the planning submission and the report on the environmental impact were revised in accordance with the requirements of the SFOE. At the end of October 2010, the environmental impact assessment (EIA) report was submitted to the Federal Inspectorate for Heavy Current Installations (ESTI) for preliminary checking and approval of the specifications. In February 2011, a visual inspection took place with the cantonal and national authorities under the leadership of the Swiss Federal Office of the Environment (FOEN). The EIA was revised on the basis of this inspection.

In January 2012, information events took place in Zernez in order to provide information to the municipalities, environmental organisations, public and press. Between April 2012 and November 2013, the application documents were fundamentally revised in the light of the SFOE's new assessment scheme for transmission lines as well as various court judgements. Upon submission of the planning dossier to the Federal Inspectorate for Heavy Current Installations on 9 December 2013, the planning approval procedure (PAP) was initiated. In May 2016, the Federal Inspectorate for Heavy Current Installations gave its approval to the expansion of the 380-kilovolt line between Pradella and La Punt.

Project changes: Replacement rather than reinforcement of 50 pylons

During the preparations for the construction work, Swissgrid checked the pylon statics and determined that some pylons were too weak for the planned expansion of the route to two 380 kV lines. Based on these findings, Swissgrid decided to replace 50 pylons instead of reinforcing them. This change to the project will not result in any changes to the route. As a result, the commissioning of the upgraded line will be delayed by at least one year and is now scheduled for 2022. The project amendment was published by the municipalities between 19 September and 21 October 2019. The Federal Inspectorate for Heavy Current Installations (ESTI) issued the construction permit for this project change on 7 July 2020.

Project progress and project planning

Swissgrid carried out the civil engineering work from 2017 to autumn 2019. During this time, the pylon foundations were reinforced and the concrete bases renovated at each pylon location. The next step involves reinforcing or replacing the pylons where necessary. Swissgrid is planning to undertake the first stage of the construction work (from Pradella to Zernez) in 2021, and the second stage (from Zernez to La Punt) will follow in 2022. All pylons will receive a green protective coating. The grid project is expected to be completed by the end of 2022.

Existing 380 kV overhead line Pradella – La Punt
1/7: Existing 380 kV overhead line Pradella – La Punt
Construction of the new 110 kV line between Pradella and Bever (source: EKW)
2/7: Construction of the new 110 kV line between Pradella and Bever (source: EKW)
Repair of the pylon foundations
3/7: Repair of the pylon foundations
Civil engineering works: foundation reinforcement
4/7: Civil engineering works: foundation reinforcement
Civil engineering works: foundation reinforcement
5/7: Civil engineering works: foundation reinforcement
Drilling a micropile
6/7: Drilling a micropile
Construction site Pradella – La Punt
7/7: Construction site Pradella – La Punt

People & environment

Landscape

The 19 increases in pylon height, 13 new pylon tips and the use of dual instead of single conductors only has a minimal impact on the landscape in certain places. The Pradella – La Punt line has been part of the landscape for decades. Around 60% of the line runs through the forest, so it has hardly any effect on the landscape.

Fauna

Mortality among birds as a result of electrocution on the transmission grid is low. With the use of bundle conductors and a thicker ground conductor, the risk of collision for birds is reduced between Pradella and Zernez. The planned removal of distribution system lines will eliminate a major potential risk for bird life. For the remaining fauna (game animals, amphibians, reptiles) only minor effects, if any, are to be expected.

Flora, groundwater, soil

The lines will traverse marshes and protected areas. Ten pylons, whose foundations were reinforced, stand in or at the edge of dry meadows and pastures. The impact is minimal. The construction work will be supervised by a hydrogeologist in order to prevent groundwater contamination. The soil will be affected by the construction work almost exclusively in areas which are already impacted.

Forests

For the forest there will be minimal additional pollution resulting from temporary and permanent clearances, which are necessary at pylon sites and installation areas. The existing suppression of tree growth will be retained.

Electromagnetic fields

Between Pradella and La Punt there are a total of eleven locations with sensitive use. Separate calculations have been made for all the locations, which confirm compliance with the limits everywhere. The legal provisions will be complied with.

Noise

There are a total of ten buildings with noise-sensitive rooms in the vicinity of the line. Thicker conductors or triple conductors will be used to comply with the legal limits.


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