Stöckalp - Melchsee-Frutt, Rehabilitation of the foundation of the penstock

The power plant Hugschendi is located close to Stöckalp (Melchtal) and was put into operation in 1957. Two Pelton turbines with an output power of 7 MW each were installed. Water from the catchment area Melchsee-Frutt, which is stored in the Lake Tannen and Lake Melch, is released through the turbines. The gross head is around 830 m. Since the completion of the plant, the 3’385 m long penstock (Ø=0.7-0.9 m) leading from Melchsee-Frutt to the Stöckalp has been permanently in operation. At every horizontal or vertical bend of the open line, there is a fix-point. Downstream of these fix-points there is always an expansion joint, with which the longitudinal expansions can be accommodated. Between the fix-points, the penstock is held in regular intervals. On behalf of the operator Obwalden EWO, the condition of all 80 existing penstock plain bearings were registered. Depending on the assessed good to defective status of the structure, a prioritization of certain foundations and a corresponding graded schedule planning for the rehabilitation works were proposed. Based on the status report, in further commissions for the EWO, a measure planning for all foundations as well as the final design, submission and realization of a pilot project for the entire replacement of the foundations have been elaborated.
Reference location
Stöckalp - Melchsee Frutt
Final client
Elektrizitätswerke Obwalden (EWO)
Is Consortium
Start of works date
End of works date
Start of services date
End of services date
Civil designs; Construction supervision; General planning / management; Preliminary studies; Consultancy