The work site is part of a larger project that involves using 30km of tunnels to transfer the water collected to the east, in the Salazie cirque, to the west coast to provide irrigation. This is the context in which our project is to build a tunnel 18 km long and 3.6 m in diameter. 

Originally planned using a hard rock TBM (Tunnel Boring Machine), the 18 km of the Salazie tunnel were also partially excavated using explosives when hydro-geological conditions prevented using the tunnelling machine. This section was subsequently surfaced with an in situ concrete facing.