Desedimentation of Solis Reservoir, intake structure

The sedimentation problem at the Solis Reservoir is being countered with the installation of a sediment bypass tunnel. This makes it possible to siphon the sediment out of the reservoir when the water level is high, and divert it back into the Albula River below the dam. IUB Engineering Ltd was assigned the planning of the intake structure, which encompasses the following components:

  • Lake excavations (circular cell coffer dam functioning as an arch-gravity dam with 20 m water pressure on a construction base with poor load-bearing properties (lake sediments)
  • 50 m high intake structure with skimming wall and access bridge, staircase/lift tower and control room
  • Underwater debris screen (underwater dam across the whole reservoir)
  • Hydromechanical works (consisting of a hydraulic radial gate 4.7 m wide and 4.1 m high as a service gate and a stop log for inspection purposes and as an emergency closure) 

Main Data

  • Height of intake structure: 50 m
  • Depth of excavation: 20 m
  • Radial gate: 4.7 x 4.1 m
  • Max flowrate: 170 m3/s


Elektrizitätswerk der Stadt Zürich


IUB Engineering Ltd

Construction period


Construction costs

CHF 19.5 million

Scope of services

  • Verification of construction project
  • Tendering (construction, hydromechanical works, interior fittings, lift)
  • Main project
Desedimentation of Solis Reservoir, intake structure
Desedimentation of Solis Reservoir, intake structure