Partial refurbishment of the Gigerwald dam facility: work on schedule – reservoir to be fully drained

11.09.2024 - Axpo and Kraftwerke Sarganserland AG (KSL) resumed the partial refurbishment of the dam facility in June this year. The work is on schedule and extensive preparations have been completed over the last few weeks. Before the actual renovation measures can be tackled, the reservoir must be fully drained, a process expected to last until late September. Axpo and KSL are investing around 25 million Swiss francs in the partial refurbishment, thereby affirming their commitment to strengthening renewable energy in Switzerland. 

The ambitious partial refurbishment of the Gigerwald dam facility is progressing as planned. The reservoir will be fully drained by the end of September, allowing the main work to begin. With the intensive preparations completed and the logistical challenges overcome, the work can now enter the next phase.

Construction site camp occupied, traffic rerouted

The construction site camp has now been occupied and the necessary infrastructure is in place. Some changes have been made to the traffic routing in order to ensure safety: private transport is directed along a bypass road, and public access to the dam crest is prohibited during the construction work. 

All of the large machines have been delivered, some of which required special transport. The first mass deliveries of cement, gravel and reinforcing steel have been completed, and the storage areas on site have been stocked. The on-site installations, including the concrete plant, cranes, drainage systems and water and power supply, have been successfully commissioned and tested. In addition, a new installation area was created above the spillway, rocks were cleared and a rockfall protection net was installed above the structure.

Managing fish stocks in the Tamina

The preparations also included measures to protect fish stocks in the Tamina river. These were implemented in close coordination with the responsible authorities. All fish were removed from the Tamina as far as the confluence with the Görbsbach stream. This ensures that as few fish as possible will be harmed when the water level in the reservoir is lowered further. During the process of emptying the remaining water, sand will be washed into the stream, raising the water level in the Tamina significantly until the original, natural state is restored. 

Recommissioning in early summer 2025

The work on the Gigerwald dam facility remains on schedule. “We are very pleased with the progress so far and now hope for good weather so that we can continue with the work as planned,” says project manager Erich Schmid. Once the Gigerwald reservoir has been drained and the Mapragg power plant shut down, work on the dam facility is likely to continue until late April 2025. The plant is set to be put into operation again in early summer 2025.