Project Name:   La Confluencia Hydropower Scheme

Location: Rio Tinguiririca, Chile

Application: Sprayed Concrete

La Confluencia Hydroelectric plant is high up in the Andes mountains at an altitude of 1,430m and approximately 220 km south-east of Santiago. The run-of-river hydro project diverts water from the Tinguirica and Azufre rivers and discharges into an intake pond for onward supply to La Higuera Project. The project completed in 2008 provides 145 MW of renewable energy to Chile’s central grid.

The joint venture team of Consorcio Hochtief & Tesca were responsible for the planning and construction of the entire project which included drill & blast tunnels that channelled the river water and rainwater collected above ground to the electric turbines via a 360 m deep pressure shaft. Although traditional mesh and steel fibre reinforcement was considered for the reinforcement of the sprayed concrete, the contractor was very conscious of the major logistical problems of transporting hundreds of tonnes of steel reinforcement to such a remote construction site.

After careful assessment and performance verification according to the project specification a decision was made to replace the steel fibres in the tunnels with Macro-Synthetic at a dosage rate of 4kg/m3.

Outcomes:

• Significant reduction in reinforcement costs
• Performance in accordance with project specification
• Simplified Logistics and reduced delivery costs

Author:  Trevor Atkinson: trevor.atkinson@propexglobal.com