Further monitoring is underway at Colombia’s Ituango Hydroelectric Project after a further landslide on last Friday and continued ground movement in recent days.
Project owner Empresas Públicas de Medellín (EPM) evacuated more than 23,000 people downstream from the dam, which is still under construction, after a landslide on 28 April that blocked a bypass tunnel resulting in overtopping fears and downstream flooding.
The most recent landslide also forced closure of a road tunnel.
EPM has said that it is working to take the dam crest from 410m to its full height at 415m and add a further 19,000m3 of rockfill to further reinforce the structure in a bid to prevent further overflow.
Commenting on the most recent slope failure, landslide specialist Dave Petley, who is also pro-vice-chancellor (research and innovation) at University of Sheffield said: “Landslides associated with impounding of the lake at a large dam are not unusual – the stability of the slopes declines as the groundwater level rises. This latest slope failure is perhaps surprising in that it has occurred so high up the slope though.
“This site has now suffered the initial tunnel collapse, the large landslide a few hundred metres upstream of the Ituango dam site and now this small landslide above the works. These events continue to raise questions about the degree to which the geotechnical conditions of the site are fully understood. I am sure that will be a major theme as the dam is commissioned.
“In the short-term EPM are doing the right things in maintaining the evacuations, strengthening the crest of the dam and monitoring the slopes.”