Taconnaz: A challenging hydro plant at the foot of the Mont Blanc glacier

The Taconnaz project, between Chamonix and Les Houches municipalities in France, is a 4.5 MW, high head hydro plant. The Tyrolean water intake, sand trap, penstock and plant are all located in an avalanche corridor of unstable moraines, from the valley to the foot of the Mont Blanc glacier. This corridor is full of potential dangers, such as avalanches, collapse of ice cliff, rockfall, torrential floods, lava flow and instability of rocky walls. It is also home to an endemic flora which is under conservation. Commissioning of the plant is scheduled for the end of this year. This article details the identified risks and the solutions implemented to equip the Taconnaz site and an overview of construction techniques used.