Rehabilitation of the Upper Reservoir BS1 of the Pumped Storage Plant in Coo – Trois-Ponts, Belgium

The existing pumped storage plant Coo in Trois-Ponts has two upper basins (Coo 1 & Coo 2), both being located on Mont de Brume, and a single lower reservoir located at an ancient river bend of the Amblève River. The plant was commissioned in two stages, Coo 1 (1969) and Coo 2 (1978). It has an installed capacity of 1,164 MW and an effective head of about 275 m. The active storage volume of the combined upper Coo reservoirs amounts to 8,450,000 m³.

Both upper reservoirs are formed by asphalt concrete face rockfill dams. Due to ongoing deterioration, rehabilitation measures are required on the upstream face of Coo 1. The asphalt concrete comprises environmentally harmful asbestos fibres. Electrabel therefore decided to rehabilitate the damaged slopes with geo-membranes, totalling approximately 100,000 m². Lahmeyer International GmbH provides services for asphalt concrete laboratory investigation, in situ testing of geomembranes, detailed design, tender documents preparation and assistance of the Client during the tender process. The works, envisaged to be carried out in 2017, will be supervised by Lahmeyer International GmbH as well. 

ClientElectrabel – ENGIE
Execution06/2015 – 09/2017
Technical Data
  • Reservoir volume Coo I
4 million m³
  • Reservoir volume Coo II
4.5 million m³
  • Installed capacity
1,164 MW
(Coo I: 474 MW; Coo II: 690 MW)
  • Active storage volume of upper Coo reservoirs
8,450,000 m³
  • Dam type
Asphalt concrete face rockfill dams
  • Planning of geotechnical investigations, laboratory testing of the foundation and the asphalt concrete
  • Planning and supervision of in situ testing programs with geomembranes
  • Wind study
  • Detailed design of rehabilitation measures (geomembranes, fixation and interfaces)
  • Crest and ramp design
  • Cost estimates
  • Preparation of tender documents
  • Assistance of the Client during the tender process
  • Site supervision

Project Search

Follow us:LinkedInLahmeyer Blog