The Ituango Dam, also referred to as the Pescadero-Ituango Dam or Hidroituango, is an

embankment dam An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface and ...

currently under construction on the

Cauca River The Cauca River () is a river in Colombia that lies between the Occidental and Central cordilleras. From its headwaters in southwestern Colombia near the city of Popayán, it joins the Magdalena River near Magangue in Bolivar Department, and th ...

near

Ituango Ituango is a town and municipality in the Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pac ...

Antioquia Department ) , anthem = Himno de Antioquia , image_map = Antioquia in Colombia (mainland).svg , map_alt = , map_caption = Antioquia shown in red , image_ma ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

. The primary purpose of the project is hydroelectric power generation and its power plant will have an

installed capacity Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity, or maximum effect, is the intended full-load sustained output of a facility such as a power station,

of if completed. Preliminary construction on the dam began in September 2011 and the power plant was expected to begin operations in late 2018, but will not after heavy rainfall and landslides in April/May 2018 blocked the river's diversion tunnel, threatening a breach of the dam. If completed, it will be the largest power station in Colombia.

Background

The dam's feasibility study was completed in 1983 but the project was shelved in the 1990s due to an economic crisis. The final designs for the project were finished in 2008 and on 8 July 2011, the project management contract was awarded. Preliminary construction (surveying, roads, bridges, diversion tunnels) began in September 2011 and it is expected to be complete in 2013. Main works will begin thereafter and the power plant is expected to being commissioning in 2018. Development of the project is being proposed by EPM Ituango, a consortium of Empresas Publicas de Medellin (EPM) and the Antioquia government. The total cost is expected to be US$2.8 billion.

Design

The dam will be a tall earth-fill embankment type with a clay core. The volume of the dam will be . Its

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

will have a capacity of of which will be active (or "useful") capacity. The reservoir will be long and cover an area of . To maintain reservoir levels, the dam will have a

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

controlled by four

radial gate The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow. It is named for Wisconsin structural engineer Jeremiah Burnham Tainter. A side view of a Tainter gate resembles a slice of pie with the c ...

s with a design flow of . The dam's power plant will have a nominal

hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...

of and contain eight

Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The proces ...

-generators.

Diversion tunnel blockage

Three tunnels were constructed to divert the Cauca River around the construction site. Two were eventually sealed during construction, leaving a third to divert the river. Between 28 April and 7 May 2018, three landslides blocked the tunnel, leading the reservoir to fill. Engineers attempted to open the two closed tunnels with explosives but were unsuccessful. On 10 May, when the reservoir reached the power station intake, engineers began releasing water through the unfinished power house to prevent a breach of the dam. On 12 May one of the previous sealed tunnels naturally reopened, which suddenly increased downstream flows by three times the average. This promoted evacuations downstream, eventually totaling around 25,000. On May 16 silt build-up in a portion of the power house, the only means to drain the reservoir, led to water escaping into a transit gallery used by construction vehicles. The water eventually poured onto the downstream face of the dam, eroding the roadway and a portion of the

riprap Riprap (in North American English), also known as rip rap, rip-rap, shot rock, rock armour (in British English) or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. ...

. Subsequently, EPM announced a risk of collapse existed and workers continued to fill the dam to its design height in hopes the spillway could be used to prevent an over-topping of the dam. Heavy rainfall was expected in the Cauca River basin through the end of May. On May 19 the dam works reached level 405 masl; 5 m below cofferdam target the level. On May 25 Dr Ordoñez issued a letter expressing his panic about the situation because "Ituango project is dead and there is no control over it, so the most natural thing is to expect it to fail; we are sure that it is easier to fail than not to fail, and we are truly in a panic".

Environmental impact

Some sources argue the dam construction has severe ecological consequences, and there are displaced families, environmentalists, youth groups and concerned locals that oppose the project. Other publications argue the project will benefit millions through extra revenue towards social and infrastructure programs. In February 2019 the Project came under increased pressure from local and national governmental regulatory agencies because of the closure of the river flow and the environmental and economic impact downstream. Moreover, studies from the

Universidad Nacional de Colombia The National University of Colombia () is a national public research university in Colombia, with general campuses in Bogotá, Medellín, Manizales and Palmira, and satellite campuses in Leticia, San Andrés, Arauca, Tumaco, and La Paz, Ces ...

showed that the failure of the dam is likely unless an emergency plan was adopted. The safety of the downstream communities was highlighted as critical. By November 2022, drills evacuated 5,000 people to prepare for the operation of the dam.

References

External links