The project includes a 5.5km-long headrace tunnel (Ø 5.64m) and a 900m-long penstock, excavated by D&B method with access adits and a surge chamber, as well as excavated slopes, for the installed power capacity of 2x105MW. The geologic conditions vary from fair quality sandstone to mudstone to poor quality and squeezing rock mass. Design procedures were required for controlling the rock mass behavior during excavation and in the long term: along the tunnel, around the portals of the access adits, and around the excavated, external slopes. The main concern of the Client were related to the adverse ground conditions and to the stability of the tunnel during construction as well as the stability of the final concrete lining and of the artificially-cut slopes in colluvium.

Geodata was appointed by RCMC JV when the project was in severe delay with respect to the contract schedule. Geodata provided special advice to define the weakness of the project by developing the alternative detailed design solution of the headrace tunnel and of the underground works. The assignment also included the technical assistance during construction.