EPM discloses progress of reconstruction of 2.4 GW Ituango hydroelectric dam

Empresas Públicas de Medellín (EPM) has disclosed to Superfinanciera, Colombia’s financial market regulator, its progress in reconstructing the 2.4 GW Ituango hydroelectric power plant after a series of landslides at the site, in Antioquia, north-west Colombia, caused the company to postpone construction indefinitely.

The dam wall has now been heightened to 418m above sea level downstream from the plant and 403m upstream and is expected to reach a final height of 435m in the first quarter of 2019. Additionally, cement injections have been completed to strengthen the contact between the massif and dam. Work is advancing to install a concrete and bentonite screen to guarantee the dam’s impermeability.

EPM is preparing to close the turbine rooms, which were opened in May to prevent catastrophic flooding. The timing of the closing depends on rainfall, the behavior of the dam following installation of the screen and the progress of the unblocking of the tunnel and auxiliary spillway gallery.

The company is also reinforcing the intermediate gallery tunnel with concrete coating, depressurizing the chamber, emptying infiltrated waters and reinforcing existing plugs. Once plug reinforcement is complete, the gates chamber of the auxiliary diversion spillway will be evaluated to determine if they can be closed.

Cement injection tests are being carried out to determine the effectiveness of the initial consolidation treatment of the gravel inside the right diversion tunnel, with an aim to proceed with its pre-plugging. In turn, in the left diversion tunnel downstream of the final plug, the infiltration water is being pumped. The entrances of the diversion tunnels are currently blocked due to a collapse that occurred in late April.

EPM is also building an access road to the upper part of the dam, to allow the start of treatment and stabilization of the landslide by means of controlled excavations.