Hochtief-Tecsa is building the La Confluencia Hydropower Scheme as an EPC contractor. The project is located 200 kilometres south of Santiago de Chile, in the Andean mountain range, close to the boarder to Argentina.
Two main intakes and five secondary intakes collect water from both the Tinguiririca and Portillo valleys. An off-river reservoir with a daily storage capacity of 1.2 million m3 is located close to the Tinguiririca main intake.
20 km tunnels (pressure and free-flow tunnels) transport the water from the main intakes to the powerhouse area, which is located at the confluence of Tinguiririca and Portillo rivers. The tunnels are all unlined and executed by drill and blast. The secondary intakes are connected to the main tunnels by vortex shafts, some of them 70 metres deep. Both main tunnels meet at the surge shaft, from where the water flows through a pressure shaft and high-pressure tunnel to the powerhouse. The powerhouse is designed for a design flow of 52.5 m3/s the two Francis turbines have a total capacity of 160 MW.
Pöyry's services for the EPC contractor Hochtief Tecsa included tender design and basic design.