Implenia and Risa AS win complex Infrastructure job in Norway

Dietlikon, 22 December 2017 - Implenia, in partnership with Risa AS, has won a contract from energy company Agder Energi. The consortium will build a dam and a new transfer tunnel. The contract for this complex infrastructure project is worth approximately NOK 600 million (CHF 70 million).

At 210 metres long and 40 metres high at its highest point, the new dam will double the reservoir's capacity to 46 million m3. The old dam will be demolished. The transfer tunnel that takes water from Lake Langevatn to Lake Nåvatn is vulnerable to rock collapses. Implenia and its partner are therefore rebuilding a 7-kilometre section of the tunnel, which is 13 kilometres long in total, in parallel with the existing tunnel. The four current tunnel inflows will be redirected to the new tunnel or rebuilt. Apart from during certain clearly defined times, the reservoir and the existing tunnel will continue to operate throughout the entire construction period of around three years. The project is scheduled for completion at the end of 2020.

The job presents various technical challenges. Despite the reduced water level in the Langevatn, there is likely to be water throughout the construction site. The new inflows for the transfer tunnel will also have to be built in flowing water, so the team will have to cope with constantly changing water levels. "We are very pleased to have won this order. It shows that Implenia can combine a high level of specialist expertise with a competitive offer," says Tone H. Bachke, CEO of Implenia Norge. "This is an exciting project, which fits well with our strategic aim in the hydroelectric power sector. Dialogue with Implenia and the customer Agder Energi has been very good, as has the trust shown by all sides; we look forward to working together with Implenia," says Trond V. Tvedt, CEO of Risa AS.

The Langevatn reservoir is located in the Norwegian municipality of Åseral in Vest-Agder. Implenia, in partnership with Risa AS, is building a new dam and a tunnel. (Picture: Anders Martinsen / Agder Energi)