Idalpe snow-making system and Viderböden reservoir, Ischgl

“Heart transplant” on the Idalpe including snow storage, pumping stations and modifications to various distribution stations.


  • Overall planning and management during the construction phase for the expansion of the Idalpe snow-making facility with the Viderböden reservoir in Ischgl (AT)
  • Overall planning with submission plan, tendering and awarding, execution planning, overall technical and commercial management, commissioning, approval
  • Responsible for all engineering services including civil engineering, reservoir construction, pipeline construction, electromechanical equipment and geotechnical engineering
  • Overall analysis and integration of the system into a system consisting of 15 pump stations and a large number of compressor and valve stations

Facts & Figures


AEP Planung und Beratung GmbH



Area of expertise

Water + Environment

Construction style

New construction, expansion

Construction type

Alpine technology + snow-making systems

Work carried out

Earthworks, master builder works, pipeline construction, electromechanical equipment


Silvrettaseilbahn AG

Project description

Since 1985, the Silvrettaseilbahn AG has been operating the Idalpe large-scale snow-making facility, which has been expanded in several stages.

The Idalpe reservoir (S1) with its associated system components is the centrepiece of the snow-making facility. The upper slope, and especially the lower slope, of the existing reservoir are affected by slope movements. The Idalpe reservoir, which forms the centrepiece of the snow-making facility, could not be operated any more after the end of the 2016/17 winter season.

To replace the Idalpe reservoir, SSAG has therefore been searching intensively since the summer of 2015 for a new reservoir pond near the Idalpe that is geologically suitable. The new Viderböden reservoir site with a usable capacity of around 58,000 m³ was therefore the key feature of the expansion project.

A "heart transplant" from the Idalpe reservoir (S1) to the Viderböden reservoir pond (S8) has literally been carried out for the realisation of the Viderböden reservoir (S8) project and the assumption of the function as the centrepiece of the Idalpe snow-making facility.

Due to the altitude of around 2,300 metres above sea level, construction of the storage pond and the associated components did not start until the end of May 2017, which meant that a tight schedule had to be kept. Despite the extensive earthworks with around 130,000 m³ of excavated material for the reservoir pond (in bedrock for the most part), it was possible to start laying the sealing system in mid-August. The reservoir was filled for the first time on 20 Sept. 2017. Trial operation and commissioning began at the end of September, 2017.

Components of the 2017 and 2018 expansion project

  • Viderböden reservoir pond (S8) with a usable capacity of 58,000 m³: In coordination with the Torrent and Avalanche Control (WLV), the reservoir pond also functions as a retention reservoir. It was constructed with earth embankments and a foil liner. The liner was covered with protective fleece and gravel. The surplus material from the reservoir pond was used nearby to improve the existing man-made and over-worked surfaces of the slopes.
  • Backing pump station Viderböden P14 with a water capacity of 400 l/s (integrated at the foot of the dam)
  • Main pump station Viderböden P15 with a water capacity of 400 l/s (located near the berm above the water level of the reservoir pond)
  • Catchment structure Idbach-Ast Piste 13 for annual initial filling and discharging of flood waters for retention purposes with max. 1200 l/s
  • Pipeline with a total of 12 segments for connection to the existing pipeline network
  • Expansion of Valve Station A3 and Compressor Station K1 in the Gampenbahn valley station