The blasting of a demolition charge marked the official start of the construction work for the new Spitallamm replacement dam at Lake Grimsel on 20 June 2019. The CEO of Kraftwerke Oberhasli AG, Daniel Fischlin, opened the celebrations on the construction site with a speech that referenced and praised the pioneering work carried out by the engineers and construction workers who built the first dam wall over 90 years ago. “Lake Grimsel and Lake Gelmer are the source of the KWO plant complex and – with around half the reservoir volume – also the heart and identity of KWO,” continued Fischlin. Martin Eschle, Vice-Chairman of the Board of Directors of KWO and a member of the Executive Committee of the Basel-based energy supplier IWB, put the construction of the dam wall into perspective: “The replacement of the Spitallamm dam wall is not only essential for KWO, but also for providing electricity for the whole of Switzerland.” Other speakers included Luc Frutiger, Co-Owner and Delegate of the Board of Directors of the Frutiger Group, who was in attendance as a representative of the Grimsel Joint Venture, which has been commissioned by KWO to build the dam wall, as well as Ralf Grand, Head Foreman at KWO. The kick-off celebrations were attended by some 60 guests, including representatives from the KWO Board of Directors, the Grimsel Joint Venture, the municipality of Guttannen, and KWO stakeholders.
The celebrations were heralded by a loud bang 
Daniel Fischlin, CEO KWO 
Martin Eschle, Vice-Chairman of the Board of Directors 
The old Spitallamm dam wall at Lake Grimsel
Luc Frutiger, Co-Owner of the Frutiger Group and representative of the Grimsel Joint Venture
Around 60 guests watching the fireworks display on the Spitallamm dam 
Member of the KWO Board of Directors Andreas Stettler and KWO CEO Daniel Fischlin 
Ralf Grand, Head Foreman at KWO, provides information about the upcoming work 
Applause for the fireworks display 
Thomas Huber, moderator and Head of Communications at KWO 
Member of the KWO Board of Directors, the Grimsel Joint Venture and KWO employees prior to the kick-off 
Rudolf Lagger, member of the Executive Committee of Frutiger AG, pictured with Dominik Ghelma, member of the Executive Committee of Ghelma AG Baubetriebe, and Benno Schwegler, Head of Projects at KWO
Excavation to be carried out in two-shift operation seven days a week
Following the official kick-off, work will now commence on the construction of the replacement Spitallamm dam wall at Lake Grimsel, with the excavation of the southern access tunnel already having begun. This tunnel will provide large machinery with access to both the new and existing dam walls. Over the next few weeks, the workers will excavate the access tunnel in two-shift operation seven days a week. The tunnel will grow seven metres longer every day, which means that the new access tunnel will finally extend to the dam walls by the end of September 2019.
At the same time as the excavation of the new access tunnel, the workers will set up the infrastructure required for the construction of the replacement dam wall. This includes access roads, the water and power supplies, the drainage systems, accommodation for the workers on the construction site, and offices. Approximately 40 sleeping berths will be set up at Grimselnollen, with a further 32 berths already in place in Guttannen. This means that around 75% of the workers will be able to sleep overnight on site.
One of the main challenges that needs to be overcome in the work is the proximity of the tunnel to the existing infrastructure, i.e. the electricity pylons, the historic Grimsel Hospiz hotel, the existing dam wall and its secondary structures. A whole host of measuring instruments will record the vibrations caused by the construction work and the demolitions. If necessary, the construction workers can respond appropriately and make adjustments. At the end of June, work will begin on the construction of a cableway, which can transport up to nine tonnes of materials and will stretch between the Juchli cliff face and Grimselnollen. Among other tasks, the cableway will be used for transporting machinery to and from the site and for supplying the explosives used for excavating the foundations. Work will begin on blasting the rock face and excavating the materials at the start of September and will also be carried out seven days a week. The excavation work is scheduled to be completed in 2020, with the gravel quarry at Gerstenegg and the concrete plant at the foot of the new dam wall subsequently being put into operation. The actual construction of the new dam wall, i.e. the visible concrete work, will start in 2021 and should be completed in 2025.