Colombia’s largest hydroelectric dam will evacuate to investigate a sinkhole which could collapse the entire structure or its supporting mountain.
Populations downstream could face catastrophic flooding: Puerto Valdivia is on red alert, with Puerto Antioquia, Caceres, and Taraza on orange alert, according to the national risk management agency UNGRD.
Water moving through a turbine chamber has created a sinkhole of at least 60 foot deep in the mountain that supports the dam.
At midnight Wednesday, Medellin public utilities company EPM will close one of the gates leading to the flooded turbine chamber in order to assess the damage to the dam and the mountain.
The gate closure is crucial to determining how determine whether the dam is viable or needs to be deconstructed.
Because this operation could cause pressure on the dam and the apparently weakened mountain, all 1,000 workers at the project will be evacuated and nearby roads will be closed.
Towns downstream the troubled project were evacuated in May last year already.
There will be an evacuation of everyone in the project, and only the five people responsible for closing the gate will remain there.
Medellin Mayor Federico Gutierrez
Medellin Mayor Federico Gutierrez named the five engineers who will stay at the dam during the high-risk operation “heroes.” The remaining engineers will be in communication with a command post in a ‘Crisis Room’ at a safe distance, managed by Medellin’s mayor and the manager of EPM.
During the closure, there will be a number of helicopters including ambulances, 57 sirens ready to sound and hundreds of emergency personnel will be deployed in the Bajo Cauca region and near the dam.
According to EPM, the situation at the dam is currently stable. Monitoring from 600 sensors installed in the mountain shows that nothing has changed in recent days, EPM’s acting director Jhon Maya Salazar told La Republica.
The company, however, has been accused of consistently trying to understate the seriousness of the situation.
The dam has been in trouble since May 2018, when EPM closed the original discharge tunnels prematurely, causing water in the reservoir to rise. This rise flooded communities upstream and threatened to rise above the level of the retaining wall. Tens of thousands were evacuated from the dam project in northern Antioquia all the way to the Caribbean Coast.