Modernization and Performance Upgrade

Overhaul of the upper basin

Once the embankment has been cleaned using high-pressure devices, a new 2 to 3-millimeter-thick layer of mastic will be applied using a special drawing cart. Mastic, made of bitumen and powdered rock, protects the existing bituminous concrete insulation from aging caused by UV radiation. The inlet structure's locks will be removed and retreated for preservation.

Overhaul of the Surge Tank and Underwater Galleries

In the surge tank, rock anchors that are inaccessible during operation will be checked, and the anchor heads will be retreated for preservation. Faults in the jetcrete lining and the concrete installations will be serviced. Furthermore, the measurement devices used to monitor the rock cavity will be replaced. New protective coatings will be applied to the fall-protection scaffolding, which can be used to close the water route to the cavern.

Overhaul of the High-Pressure Pipelines and Pipes

The pressurized duct (diameter: 5.75 meters) from the upper basin to the pipeline array upstream of the machines and the underwater galleries (diameter: 4.9 meters) which extend close to the underwater surge tank, will be lined with steel pipes. Including the pipeline array, the pipes have a total length of some 1,000 meters. A new anti-corrosion coating will be applied to a surface of about 15,000 square meters.