forecasts, snow conditions, and judging the degree of danger to which the site and access routes are exposed. The safety perception of workers can also be significantly increased.
And when working in colder climates, dam designs or working practices can also evolved within the region The choice of reducing the concrete quantity to be poured and especially preparing the formworks on site by prefabrication can help in avoiding complex formwork installation as well as rebars positioning in harsh climate conditions. The chance to reduce the overall construction time is evident. Redundancy in construction site logistics can also play a role.
Gigerwald A mild winter played a helping hand in the recent
upgrading of the Gigerwald outlet project in Switzerland. Carried out by Axpo and Kraftwerke Sarganserland, it was completed on schedule, on time and without any major incidents. The raising of the inlet structures for the works water and the bottom outlet had become necessary due to increased silting up of the lake bed. It took 50 employees six months to build at the base of the 150m high dam. The work should have been carried out as early as
2022, but was postponed due to concerns about a potential electricity shortage across Switzerland. In the summer of 2024, high levels of sand recorded in the turbine water were a clear sign sediment in the lakebed had already reached the height of the existing inlet structures. So emptying of the reservoir was carried out earlier than planned. A mild winter with little snow helped the tight schedule which didn’t really allow for any major delays. Everything had to be ready before the snow started to melt because larger amounts of water would have stopped construction. Thankfully this wasn’t the case due to meticulous planning and intensive preparations on site which began in June 2024. At the end of March 2025, just in time before the thaw set in, the main work at the foot of the Gigerwald dam was completed ahead of schedule. This was by no means a matter of course, as the unusual construction site presented extraordinary challenges for the project management and employees. The time invested in the preparation resulted in an overall reduction of the construction time. It was a good example of great teamwork between the owner’s representatives, contractor, site managers and designers helped keep the project on track.
Above left: Installation of concrete precast loss formworks for intake shaft under winter conditions
Above middle: Thanks to the straightforward assembly of the prefabricated parts, the bottom outlet and water intake are quickly taking shape
Above right: Close up of the new power intake structure, piles and beams were precast and installed with high precision requirements
Below left: Bottom outlet and power intake upgrade is completed, the Gigerwald reservoir is filling, and the old intake will soon disappear
Below middle: Gigerwald dam and the new structures as seen from upstream during reservoir filling
Below: Construction supervision team in front of the new water intake
www.waterpowermagazine.com | August 2025 | 33
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