Uruguay River basin projects underground works

The large scale hydropower development of the Brazilian Uruguay River basin is planned with four major projects within the next decade: Itá - 1620 MW; Campos Novos -880 MW; Machadinho - 1200 MW and Barra Grande - 920 MW. Hydropower development is favored by the physical characteristics of the sites, featuring high gradient rivers, narrow valleys and sound rock foundations. Such features, the high runoff and the local topography led to design with high capacity diversion and power tunnels, that are standard for most of the projects. The underground works comprise more than 1.5 million cubic meters of rock excavation for the four projects. High flow velocities are accepted in the unlined diversion tunnels. The geomechanical conditions of the rock mass are considered for the design of drainage and stabilization measures. Detailed construction planning was carried out to support design studies, cost estimation and bid evaluation.