ABSTRACT
In the North of Portugal, a new hydroelectric scheme was carried out. The new hydropower plant is a repowering of the Salamonde facility functioning since 1953. This repower consists of an energy improvement up to 386 GWh annual production, by the installation of additional 224 MW of production capacity. Part of this new scheme included the construction of a new powerhouse cavern, 165 m deep, on the Gerês granitic rock mass, a large surge chamber, a mainly vertical shaft headrace circuit and a 1930 m long, unlined, tailrace tunnel. In this paper the geological and geotechnical characteristics are summarized, the underground work design is presented as well as the most relevant aspects of the powerhouse cavern and tailrace construction phase, including the results of the monitoring system installed. EDP Gestão da Produção de Energia (EDPP) is the owner of this repowering project, the designer was COBA Group and the company “Construsalamonde, ACE” (a joint venture composed by Teixeira Duarte-Engenharia e Construções, S.A., EPOS-Empresa Portuguesa de Obras Subterrâneas, S.A. and SETH-Sociedade de Empreitadas e Trabalhos Hidráulicos, S.A.) was the contractor.
