Kraftwerke Oberhasli have asked the Arge Grimsel consortium of Frutiger, Implenia and Ghelma to replace the Spitallamm dam. The existing Spitallamm dam was built in 1932. The new double-curvature arch dam is to be built directly in front of the old dam wall. The crown of the new structure is as high as the old arch-gravity dam, though if the Grimselsee reservoir is enlarged at a later stage, it will be possible to increase the height.
The wall will be 113m high without reservoir enlargement. The old dam will remain in place and will be filled on both sides.
A tunnel will be built to help maintain the hydraulic balance of the water level. Along with some further underground structures, the contract includes the processing of materials to produce more than 220,000m3 of concrete.
Work begins in summer 2019 and should be completed in 2025.