Hidroituango Dam Failure

What happens when schedule and cost try to supersede engineering reality? Nothing good. (I haven't had an infrastructure post in a while; I thought it might be good to get back into that.)

Today we have the story of an engineering disaster from 2018. The Ituango Hydroelectric Dam in Colombia. Hidroituango, failed engineering, wrong decision-making, or simple ambition?

Note: Colombia is the name of a South American country. Columbia is the name of a record club from the 1970s that could get you cheap vinyl, but was really difficult to quit. For this reason, most of the articles on the subject are in Spanish. Most of the those that have been translated into English have some problems.

The project in question is a hydroelectric dam on the Cauca River near the city of Ituango in Antioquia Department, Colombia. There are 32 departments in Colombia, and while it is tempting to think of them as states, they are just administrative divisions.

Three diversion tunnels were dug to route the river around the site of the dam and powerhouse. The original design called for there to be a sluice gate system for regulating the flow through the tunnels. Those gates were not constructed.

Near the end of construction, 2 of the 3 diversion tunnels were sealed by the construction company. It isn't clear to me why that was done. During construction of the powerhouse, the third tunnel was blocked by a landslide and the reservoir began to fill. (Some reports call that landslide an internal collapse of the tunnel; either would be bad.)

Further landslides followed and with water levels rising and all outlets now blocked, EPM decided to flood the dam's turbine rooms on 10 May to release the river's increasing pressure on the structure.

While the move caused irreparable damage to transformers and other systems which had already been installed in the turbine room, it did reduce water levels.

But only two days later, one of the sealed tunnels naturally unblocked, causing water to gush through it and creating flash floods further downstream.

Since then studies indicate that there is a risk of more landslides, which could block both the diversion tunnels and the intake for the powerhouse. If that happens there will be no way to drain the reservoir, and it will eventually overtop the dam. This would ultimately result in a catastrophic failure of the dam with a full reservoir.

Why were the controls on the diversion tunnels not built? Why were the diversion tunnels sealed? Why was the geology not better understood? (Landslides and failed seals?) The answer seems to be budgets and timelines. Though most of the reports are in government-speak that has been translated from Spanish.

Here is a key paragraph from another source. Hidroituango or: The greatest project nobody wants to take responsibility for

It is evident by now that local stakeholders made changes in the designs of the project in order to finish it on time and that these changes resulted in a series of engineering mishaps that caused the current emergency. In their desire to see the project through and their ambition to demonstrate the prowess of Antioquian engineering they forgot to incorporate lessons learned from past projects. They have caused incalculable environmental damage to the Cauca river basin, displaced local communities, endangered the finances of the region (and possibly the country). They have also brought about energy uncertainty. Although investigations into possible wrongdoing have begun, it is very unlikely powerful people will be held accountable for the damage they have caused.

This is the best report I've found, though it is not "official" in the way most reports are. EPM’s Hidroituango: New Report By Independent Geological Engineering Expert Challenges Existing Narrative. It seems to highlight some of the problems both with the design and the construction of the diversion tunnel.

This is a short video that captured the moment (just after) the seals on the diversion tunnels failed. (The video I wanted to use has disappeared, but this one isn't bad...) Fail Hidroituango Colombia Dam Hydroelectric