The Grand Ethiopian Renaissance Dam (GERD) is built by the Italian general contractor Salini-Impregilo, today called Webuild. Since 2011 the dam is under construction near Ethiopia’s border with Sudan on the Blue Nile. It’s one of the largest gravity dams in the world: 155m high and 1780m long. The major benefit of the dam will be hydropower production, with an installed capacity of >6’000 MW and an expected power generation of 15K GWh per year. All the energy generated by the GERD will be going into the national grid of Ethiopia to support the economic development of the whole country.
In 2013 Smartec SA was selected to supply a distributed fiber optic temperature monitoring system for the entire dam, with almost 12’000m of distributed sensing cable (figure 1) and more than 6’000m of connecting cable.
Figure 1, reels of armored distributed temperature sensing cable
The main objective of the fiber optic monitoring system is to provide important information on the concrete temperature during concrete pouring and setting. Once this phase is completed, the cable is used both as a continuous temperature sensor and as a leak detector and localization system.
Four powerful DiTemp Harsh reading units (figure 2) are working continuously, ensuring the collection of thousands of data points each day and every meter or sensing cable.
Figure 2, reading unit: robust, compact, reliable and
The DiTemp sensing cables are directly embedded in concrete, but direct contact with large and sharps aggregates that might damage it must be avoided. The cable was therefore laid inside a groove and filled with a finer-graded mortar, see Figure 3.
Figure 3, cable installation in the mortar-filled groove and radius of curvature
A key aspect of a distributed monitoring project is represented by the definition and implementation of a coordinate system. This allows for defining several alert zones, according to the client’s requirements, which will be handled by the DiView monitoring software installed on a central server. The coordinate system allows an easy and quick understanding of the exact location of leaks or other temperature events.
The construction of the dam is in progress, with completion scheduled for 2021 / 2022 when also the fiber optic leak detection system will be fully operational.
The picture was taken from middle-east-online.com
