Construction is to commence at the Grimsel site in the Bernese Oberland at the beginning of June 2019. The Spitallamm dam, one of two walls damming the Grimselsee, is to be rebuilt.

The Supervisory Board of Kraftwerke Oberhasli AG recently passed the resolution approving the construction. The KWO estimates the replacement construction of the Spitallamm wall to cost 125 million Swiss Francs. The old 114 metre high Spitallamm dam on the Grimsel was built between 1925 and 1932. The Spitallamm dam wall has however shown irreversible deformation for quite some time. Detailed investigations by the KWO have determined that new construction is the most economically and technically sensible solution, better than partial demolition and renovation of the existing wall. The current Spitallamm dam is to remain in place and later submerged. A tunnel next to the old wall ensures hydraulic compensation of the water level. It is of central importance for the Oberhasli power plants that it is possible to use the water from Lake Grimsel, at the heart of the power plant system, for electricity production without restriction for the entire duration of the construction work. The construction work is expected to take six years.