The baptism of the mini-tunneller

Grid project Connection Nant de Drance

An extra-high-voltage line delivered ready for use

Interview with Nicolas Pagani, Head of the Large-Scale Construction sector at CSC costruzioni SA

Author: Marie-Claude Debons


For the first time in the company’s history, Swissgrid has awarded a general contractor mandate for the construction of an extra-high-voltage line: the Vertiaz consortium has been commissioned to design and build the entire underground cable link between La Bâtiaz substation and Le Verney in Martigny, Valais. Work is currently in full swing and the final tranche of this 380 kilovolt line, which connects the Nant de Drance pumped storage power plant to the electricity transmission grid, will be put into service in 2022. But who is the Vertiaz consortium and what does this general contractor mandate entail?

Mini-tunneller Giorgia
Giorgia, the mini-tunneller in the colours of Valais and the logos of the companies working on this project

Nicolas Pagani, Head of the Large-Scale Construction sector at CSC costruzioni SA (Webuild group), provides further details in this interview.


Who is the Vertiaz consortium?
Nicolas Pagani: The Vertiaz consortium is made up of the companies Webuild S.p.A. and CSC costruzioni SA. Webuild is a multinational company listed on the Milan stock exchange and active in 50 countries. It has over 70,000 employees worldwide. This group owns 100% of CSC, which operates autonomously throughout Switzerland. CSC is a construction company founded in Lugano in 1960, specialising in large-scale construction and civil engineering. Among other things, CSC has contributed to the construction of large dams, motorways and railways, including the Gotthard base tunnel, with its parent company Webuild. In fact, CSC and Webuild, in partnership with other Swiss companies, have completed two of the main sections of the Gotthard tunnel. This historic structure is the longest railway tunnel in the world at present. In a few years’ time, however, it will be overtaken by the Brenner base railway tunnel between Italy and Austria, for which Webuild is currently working on three major sections.

What is the advantage of bringing together several companies with different areas of expertise in a consortium?
This consortium is an excellent combination of a capable Swiss company, boasting a long history and perfect knowledge of the context in which it operates, and a multinational company that brings its extensive know-how in relation to complex projects.

The mandate awarded by Swissgrid is almost unprecedented in Switzerland

Nicolas Pagani, CSC costruzioni SA

 
What mandate has Swissgrid awarded to the Vertiaz consortium in Martigny?
The mandate awarded by Swissgrid is almost unprecedented in Switzerland; it is very rare for major construction projects to be tendered under a general contracting agreement. Swissgrid took an innovative approach: it awarded the Vertiaz consortium the contract for the design and construction of a passage three metres in diameter over a distance of 1.2 km between La Bâtiaz and Le Verney. The extra-high-voltage cables that will connect the La Bâtiaz substation to the 380 kV Chamoson – Romanel overhead line at Le Verney in Martigny will be installed in this underground passage, built by a slurry TBM pipe-jacking machine at a depth of 10 and 20 metres.

The baptism of the mini-tunneller
The project managers of the various companies at the baptism of the mini-tunneller in October 2020

What is your personal role in this consortium and in the company that employs you?
I have been working at CSC for ten years as Vice Director and as a Member of the Board of Directors. I am Head of the Large-scale Construction sector for the whole of Switzerland and, in this capacity, I am responsible to Swissgrid for the La Bâtiaz – Le Verney underground cable link construction project.

We are confident that we will be able to meet this challenge, in close cooperation with the Swissgrid team.

Nicolas Pagani, CSC costruzioni SA

 
The mini-tunneller Giorgia is currently drilling the underground passage. Can you give us details about this work?
The mini-tunneller is currently about 20 metres below the surface, in the water table. Giorgia has already dug the passage under the motorway and under the Dranse river, both without any problems. The geology of the subsoil is complex and variable, but we are managing to master the difficulties we encounter. The construction deadlines are short and the work to be carried out before the underground cable link is put into service requires perfect coordination between all of the participants. We are confident that we will be able to meet this challenge, in close cooperation with the Swissgrid team.

After almost a year of work, what is your personal experience of this exceptional project?
Nothing is simple in this project; each step is a challenge in itself. The technical expertise and excellent work team, consisting of Swissgrid, the project owner; BG Ingénieurs Conseils SA, the project manager; the Vertiaz consortium, the general contractor; and Pini Swiss Engineers, the planner, is enabling us to make progress on the passage. Difficulties and surprises are usually unavoidable in this kind of major underground work. This general contracting collaboration for such a complex job is, however, one of the best experiences I have had in my entire career because the approach is innovative in Switzerland. We work according to a «problem, consultation, risk analysis, solution, execution» process that is very effective thanks, among other things, to the participation and proactive approach of all the companies working on the project.


In the interview


Author

Marie-Claude Debons
Marie-Claude Debons

Communication Manager

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