Grid project Pradella – La Punt

The Pradella – La Punt line is essential for the power transit and security of supply in the Canton of Grisons. The line between Pradella and La Punt needs to be expanded in order to fully transport the energy generated from hydropower.

Your contact for this grid project

Alessandro Cameroni
Alessandro Cameroni

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 constitutes a bottleneck in the Swiss and European transmission system. The expansion programme will increase the import capacity of power from the north, strengthen networking on the international grid (towards Austria and Italy) and improve the transportation of energy from hydropower in the Canton of Grisons. The project will also boost security of supply. The priority grid expansion programme in Engadin includes the expansion of the 380-kilovolt line between Pradella and La Punt as well as the expansion of the Pradella switching substation. 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. The construction work for the new overhead line commenced in the summer of 2017.

Improvement upon the current situation

  • The structural bottleneck between Pradella and La Punt will be eliminated, allowing more power to be transported
  • The transportation of hydropower energy in the Canton of Grisons will be improved
  • Networking on the international grid will increase towards Austria and Italy
  • It will be possible for the Engadin to have a more reliable electricity supply
  • The doubling of the 380-kilovolt circuits and the use of double and triple conductors will reduce transmission losses and minimise electromagnetic and noise emissions

Project

A second 380-kilovolt circuit will be laid along the entire length of the approximately 50-kilometre line. To enable this, the 220-kilovolt energy transmission line from the Ova Spin power plant, which is carried on the existing overhead line between Zernez and Pradella, will have to be dismantled. In future, the energy from the Ova Spin power plant will be transported via a planned 110-kilovolt valley grid.

Facts and figures

Line layout The line route will be retained with the exception of a minor adjustment where the line enters the Pradella substation
Pylons Raising and strengthening of 19 pylons
Strengthening of 55 supporting structures
Addition of tips to 13 pylons
Conductors Between Pradella and Zernez, the three phases of the existing 220-kilovolt circuit will be upgraded with an additional conductor.
Between Zernez and La Punt, an additional circuit will be added. Both circuits are comprised of three phases with twin conductors.
Ground conductor The existing steel ground conductor will be replaced over the entire length of the line with an Aldrey rope with integrated fibre-optic cables
Insulator strings The latest 380-kilovolt plastic insulator strings will be used over the entire length of the line

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.

Compensatory measures

The owners of the Engadin distribution grid, Engadiner Kraftwerke (EKW) and Repower (RE), intend to replace the existing 60-kilovolt grid with a new 110-kilovolt grid. The 60-kilovolt Pradella–Zernez–Bever line, which is to be converted to 110 kilovolts, will be laid in the form of an underground cable; this is in part a compensatory measure for the scheduled upgrade of the 380-kilovolt Pradella – La Punt line. The 220-kilovolt circuit that is also carried on the line between Pradella and Zernez will be removed.

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 progress and milestones

Construction work began in the Upper Engadine in 2017 and continued in the Lower Engadine in the summer of 2018. During this time, the pylon foundations were reinforced and the concrete bases renovated at each pylon location.

The assembly work will be carried out in the coming years. The project comprises a total of 126 pylons to be refurbished and reinforced.

Existing 380 kV overhead line Pradella – La Punt
1/5: Existing 380 kV overhead line Pradella – La Punt
Civil engineering works: foundation reinforcement
2/5: Civil engineering works: foundation reinforcement
Civil engineering works: foundation reinforcement
3/5: Civil engineering works: foundation reinforcement
Drilling a micropile
4/5: Drilling a micropile
Construction site Pradella – La Punt
5/5: Construction site Pradella – La Punt

110 kV overhead line

As part of the Pradella – La Punt project, EKW replaces the current 60 kV line with a 110 kV underground cable. The 60 kV overhead line will be dismantled after the new underground line is commissioned. This will relieve the Engadine landscape by dismantling around 1,000 pylons. The work will be completed by November 2019.

Visualisation of the project
Visualisation of the project

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

Marshes and protected areas will be spanned. Ten pylons for which foundation reinforcement measures are planned are positioned in or on the edge of dry meadows and grassland. The impact is minimal. The construction work will be conducted under hydrogeological supervision in order to prevent groundwater contamination. The soil will be affected by the construction work almost exclusively in areas that are already polluted.

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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