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 with the international grid (Austria, 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. The construction work for the new overhead line commenced in the summer of 2017.
A second 380-kilovolt circuit will be laid along the entire length of the approximately 50-kilometre line. To do so, 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. The energy from the Ova Spin power plant will in future be transported via a planned 110-kilovolt valley grid.
| Line layout | 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 | Latest 380-kilovolt plastic insulator strings over the entire length of the line |
The project was compared with a new 380-kilovolt underground cable over the whole route and in 4 sections. The comparison was made following the assessment scheme for transmission lines of the Swiss Federal Office of Energy (SFOE). The comparison indicated that the additional costs for full or partial underground cabling were disproportionately high and resulted in only partial relief of the effect on the landscape.
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 an alternative measure for the scheduled upgrade of the 380-kilovolt Pradella – La Punt line. The 220-kilovolt circuit also carried on the line between Pradella and Zernez will be removed.
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, on the basis of the Sectoral Plan for Transmission Lines (SPTL), the SPTL check 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 on the basis of the SFOE's new assessment scheme for transmission lines and because of 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.
Before the dismantling of the 220 kilovolt circuit, the 110 kilovolt line between Zernez and Pradella must be built and put into operation. The 60 kilovolt line will be dismantled after completion and commissioning of the 110 kilovolt underground cable line. This means that around 1,000 pylons and wooden posts can be removed in the Engadin.
| May 2016 | The Federal Inspectorate for Heavy Current Installations approved the expansion of the 380 kilovolt line between Pradella and La Punt |
| Summer 2017 | Initial engineering work (foundations and cable pipe conduit) commenced |
| 2021 | All work is completed |
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.
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.
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.
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.
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.
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.
