Projects |
Rebuilding underwater: the hidden engineering of the Ituango Dam
The Ituango Hydropower Project – featuring a 225m high dam and 2.4GW powerhouse – faced an unprecedented engineering challenge: an unplanned reservoir impoundment with no intake gates or dewatering systems in place. This feature explores the complex underwater rehabilitation efforts that combined precision engineering, adaptive design, and international collaboration to restore Colombia’s flagship energy infrastructure
Above – Floating Infrastructure: DCN’s saturation system (SAT- 03) and heavy lift barge (300-ton crane) supporting hyperbaric operations
Below – Hyperbaric and wet testing: DCN’s Centers for Full Class Certification
TUCKED DEEP WITHIN THE rugged mountains of Antioquia, Colombia, the Ituango Hydropower Project is a feat of modern engineering –not just for its scale or energy potential, but for the extraordinary underwater rehabilitation works that have taken place far from public view. Following an unexpected crisis during construction, the rehabilitation of Ituango wasn’t just a patch job; it was a masterclass in subsea engineering, precision design, and adaptive construction under the most demanding of conditions. in April 2018, a landslide blocked one of the diversion tunnels, initiating a chain of emergency responses that significantly impacted the partially constructed dam. Among the downstream consequences were the unplanned flooding of the machine house, structural damage to intake components, and months of interrupted construction. As part of a wide-ranging rehabilitation initiative, DCN Diving, a Dutch underwater construction specialist, was tasked with the underwater isolation of the dam’s intake structures – a critical component for future operation. This article examines the rehabilitation phase, focusing on the underwater engineering and operational decisions that enabled safe and efficient repair of submerged structures, without the need to dewater the reservoir (in this particular case dewatering was not an option because all diversion tunnels were blocked, and the water could not be regulated anymore. The surplus water from the river went over the spillway).
30 | May 2025 |
www.waterpowermagazine.com
Through advanced technology and detailed planning, the project highlights how underwater construction can provide strategic solutions to large-scale infrastructure challenges.
Engineering challenges
Following the 2018 incident, Colombian authorities and contractors began assessing the extent of the damage across multiple submerged components. The intake structures, in particular, presented both operational and technical challenges. These components were located more than 60 metres below the reservoir surface, and their rehabilitation required work in an environment of high hydrostatic pressure, zero visibility, and significant logistical complexity.
DCN Diving, known for its capabilities in complex underwater operations, was selected to carry out the intervention. Their mandate was to inspect and seal (isolate), key sections of the intake system, including embedded sealing surfaces and intake gate components. According to Arjan Bol, Commercial Director
Hydropower at DCN, the uniqueness of the Ituango project was twofold: “The Isolation work had to be done underwater in a confined space enviroment, with limited visibility and large heavy loads. That’s not unusual for us – we do it quite often – but in this case, the project carried significant political weight. There was a lot of scrutiny.”
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