A project to build one of Latin America’s largest hydroelectric schemes on the Cauca River in northern Colombia may have run more than $1bn over budget, according to a geologist at the National University in Medellin.
Professor Oswaldo Ordonez told BNamericas that a series of construction problems were likely to push up the cost of the 2.5GW Hidroituango dam, from $3.5bn to more than $4.5bn.
The project, presently the largest in Colombia, has faced a number of severe difficulties since work began in 2012.
Last year, three landslides blocked two diversion tunnels and caused the reservoir to fill and risking a breach of the unfinished dam.
Engineers attempted unsuccessfully to reopen the tunnels with explosives, and were later forced to release water through the unfinished power house.
Ordonez added: "We still don’t know the extent of the damage to the turbine rooms and the collapsed tunnels. There are also a number of lawsuits against project owner Empresas PÃºblicas de MedellÃn (EPM) that could have a large bearing on the overall cost."
The evacuation of the lower valley involved some 113,000 people and led to "the greatest environmental crime that has ever happened in Colombia", according to the Rios Vivos NGO.
EPM has now completed the main barrier, which Ordonez said reduced the project’s engineering, social and environmental risks by about half.
The dam was to have come into operation in 2018. The state-owned utility now expects it to begin generating in 2021 at the earliest. When fully operational, it may supply as much as 17% of the country’s electricity demand.
The dam is being built on Colombia’s second largest river. It will have a 225m-tall earth-fill embankment and a 19 million cubic metres reservoir stretching 127km. Its power will be generated by eight 307MW Francis turbines.
A consortium of Ferrovial Agroman Chile and Sainc Ingenieros Constructores of Colombia received a contract worth $77m in July 2011 to build a powerhouse access tunnel and two river diversions. Another team, made up of Brazil’s Carmago Correa and Colombian firms Constructora Conconcreto and Coninsa Ramon, was awarded a $66m civils contract in August 2012.
Alstom Brasil Energia e Transporte, a subsidiary of French heavy engineering group Alstom, was awarded a $226m contract to supply the turbines and other equipment.
Image: The Cauca River (Public Domain)