Execution of 725 m of galleries in prolongation of the existing ones in the dam involving drilling its abutments.
Four horizontal galleries excavated in rock, two on each edge at levels 520 and 561.
- Excavation section 8.51 m2 measuring 2.2 m in width and 2.9 m in height at the centre. Excavated using an AM.50 continuous header machine.
- Support consisting of TH-16.5 sliding steel trusses placed every 0.75 m. Anchor bolts in corrugated steel measuring 1.5 m in length and 25 mm in diameter, installing 3 bolts per linear meter. Wet spraying shotcrete with fibres measuring 10 cm thick.
- Lining the galleries with 30 cm of concrete installed with a static pump.
- Gallery grout curtain (12,841 m in drill length with 2,955 m of re-drilling).
- Gallery chimney drain to verify the effectiveness of the grout curtain (4,245 m drill length).