In 2015, the cantonal geologist of the Valais requested an additional «natural hazards» study within the framework of the Chamoson – Chippis extra-high-voltage transmission line project, more specifically between pylons 121 and 173, pursuant to the new cantonal directive on the establishment of danger zones and the related building permits. BEG was therefore commissioned to carry out the study.
In 2016, Swissgrid presented the results of this study to the Valais cantonal geologist.
This study supplements the previous studies listed in the planning approval file by the Swiss Federal Office of Energy (SFOE). It does not provide any new facts, as the siting of pylons in areas with ground instability is the subject of a building permit granted by the SFOE which, among other things, requires Swissgrid to determine the measures to be applied in collaboration with the cantonal geologist.
Specific measures are being studied and will be defined and implemented in agreement with the cantonal geologist for each pylon sited in a natural risk zone. Various measures are possible, such as installing ground movement monitoring devices, strengthening pylon foundations or reinforcing foundations using reinforced concrete beams.
Swissgrid manages 6,700 km of UHV lines in Switzerland, and many lines are installed in mountain areas characterised by steep, rocky and rough terrain. Potential ground instability areas have been identified and are being monitored. Swissgrid is aware of the situation and has it under control.
Work on the Chamoson – Chippis 380 kV overhead line is in progress and the line will be put into operation in 2021.