Axpo and Kraftwerke Sarganserland AG (KSL) have completed the main phase of the partial renovation of the Gigerwald dam in the canton of St. Gallen. The final concrete pour was carried out on Wednesday, 2 April 2025, marking the end of structural work to raise the bottom outlet and headwater intake. With the temporary dewatering system now closed, the reservoir is being refilled.
The project, which required several years of planning by Axpo and Lombardi Engineering Switzerland, focused on addressing silting issues by relocating key intake structures around 20m higher. This adjustment ensures continued operational safety of the dam and the associated power plant in Mapragg. Axpo and KSL are investing approximately CHF 25 million in the upgrade.
“Thanks to the good preparation and the great commitment of everyone involved, we were able to complete the work on schedule, according to plan and without any major incidents,” said Axpo project manager Erich Schmid.
Construction at Gigerwald Dam began in June 2024 with site preparation. The reservoir was drained in September to expose the intake structure. Core construction activities were carried out during the winter months, when water flow is lower and production losses are minimized. Up to 50 workers were deployed in two shifts, six days a week.
The Gigerwald reservoir has been refilling since the end of March. The process is expected to take about three weeks, depending on inflow rates. The Mapragg power plant is expected to resume operations by the end of April. Meanwhile, dismantling of construction installations is underway, and the dam crest path is set to reopen to the public at the end of May.
Marti Group was involved in the preparation and execution.
