The main 54km channel of the Middle Isar power station was built between 1921 and 1929. Large scale rehabilitation was required with a complete reconstruction needed of around 3,300m of the channel.Owing to the complexity of the associated power stations and sewage plants at Middle Isar, the time allowed for the shutdown to enable the works to be carried out was limited to 77 days or nights and the bituminous lining works were programmed to be completed within just 35 days. To add to the challenge for the WALO team, all transport to the site and within the site itself had to be made either by a narrow forest road and/ or the bottom of the channel, thus making the programming, scheduling and the vehicle movements to and around the site a key element of delivering the works on site, to time.

The old concrete lining was completely demolished, a control system was installed and a new sealing put in place. Approximately one third of the channel required stabilization by placing concrete slabs in the slope and base. The remaining 2,200m was constructed by the use of a bridge-paver (see photo) ensuring a ‘jointless’ construction to make the surface as strong and impermeable as possible.