Hidroituango Hydroelectric Project Repairs 65% Complete at 2-Year Anniversary of Tunnel Collapse

Medellin-based electric power giant EPM announced April 25 that the US$5 billion, 2.4-gigawatt “Hidroituango” hydroelectric power project in Antioquia – one of the world’s biggest — continues to make progress following a destructive bypass tunnel collapse two years ago.

That collapse and subsequent damage to the machine room and related facilities caused a three-year delay in startup at the project — meaning hundreds of millions of dollars of lost power sales along with infrastructure damages.

Insurance payments to date have helped EPM recoup physical damages, but final payments covering lost power sales have yet to be calculated or approved.

Following the tunnel collapse, EPM pushed-back the initial startup forecast to end-2021, rather than end-2018. However, it’s unknown whether strict, new health protocols to avoid Coronavirus infections among workers potentially might cause more delays.

Meanwhile, EPM released a new video showing some of the recent construction and recovery work at the project (see: https://bit.ly/2zvywOg). But this video doesn’t show or explain how workers are dealing with new, further restrictions arising from Coronavirus prevention protocols.

Commenting on the upcoming anniversary of the diversion tunnel collapse (April 28, 2018), EPM general manager Álvaro Guillermo Rendón López stated: “In these two years [following that incident] our company hasn’t spared efforts or resources to reduce the risks of the populations located downstream of the project and to carry out one of the most important infrastructure works in the country.”

Since then, EPM successfully drained and cleaned-out the main cave complex, removed damaged equipment (including the overhead crane) and recoated the interior walls with concrete.

“At this time, cave repair work is focused on filling and repairing a large hole created by erosion between catchments number 1 and 2. This hole is now filled and completion of sealing is in final review stage,” according to EPM.

Meanwhile, repair of the machine room cave complex is “65% complete. Daily monitoring of the structure shows 100% stability,” according to EPM.

The dam itself was completed last year, including an impermeable bentonite screen rising from 380 meters to 418 meters above sea level. The entire dam has been raised to its full height of 435 meters above sea level “as required by the project design,” according to EPM.

“With these works, the reservoir [behind the dam] can operate safely even in the face of maximum water levels projected over 10,000 years,” according to EPM.

“The current state of the dam allows control of the maximum possible risk – that is, the passage of 22,500 meters per second of water through the dam works, or the maximum foreseen flow that the Cauca River could bring.”

In November 2019, a new road built atop the dam was opened for traffic to and from the municipality of Ituango in northern Antioquia.

As for diversion tunnel works, two gates of the auxiliary diversion tunnel were repaired and reinstalled, meaning this tunnel is now “capable of withstanding the pressure of the reservoir [behind the dam] at its maximum filling level,” according to EPM.

“Recovery efforts are focused today on construction of a 23-meters-long concrete plug, which allows the gallery to be sealed. In the right diversion tunnel, where the collapse originated, a pre-stopper plug was built to enable safe advancement of construction of the final plug.

“The intermediate discharge tunnel is reinforced in its structure to increase its hydraulic capacity. From this tunnel, work is carried out on the right diversion tunnel. On another construction site, fillings and repairs are carried out in the gap between catchments 1 and 2,” according to EPM.

Social Recovery Programs

Meanwhile, 1,990 families from the township of Puerto Valdivia – temporarily evacuated following the tunnel collapse — have since returned to their homes.

“EPM continues to provide financial support to the 265 family groups that have not yet returned to their homes. The delivery of these supports amounts to about COP$31 billion [US$7.7 million],” according to EPM.

The company also has signed compensation deals for several dozen homes damaged by temporary flooding caused by the tunnel collapse, and paid for repairs at schools and other buildings.

EPM also has inked financial compensation deals with 280 merchants affected by temporary loss of sales, while claims from another 1,200 merchants await adjudication.

In addition, “to strengthen the economy in the affected populations, EPM implemented social contracting, through Asocomunal, for recovery projects and works, for a value close to COP$680 million [US$168,000],” the company added.