Deriner Dam and Hydroelectric Power Plant (HEPP), Turkey

Expected to be operational by the end of 2012, Deriner Dam will be the highest dam in Turkey and the third highest dam in the world, with a height of 253m. The double-curvature concrete arch dam is located on the Coruh River near Artvin province in the north-eastern part of Turkey.

The underground powerhouse near the dam will consist of four units, with an overall capacity of 670MW. The powerhouse will generate 2.118GWh of electrical energy annually once it becomes operational in 2012.

The project is owned by Turkey's State Hydraulics Works (DSI) and constructed by a consortium led by ERG. It is estimated to cost $1,387m.

Construction on the dam began in 1998. The project work is comprised of constructing the dam's body, rock excavation, diversion tunnel, underground powerhouse, overflow spillways, access roads and internal roads.

The concreting work began in 2005 after the excavation process had been completed, but was halted in 2007-2008 due to lack of funding. The work was, however, resumed in the last quarter of 2008 and completed in February 2012.

The hydroelectric power plant (HEPP)

The HEPP is located on the right bank of the river near the dam. The completely underground powerhouse will feature four vertical Francis turbines and is expected to generate 2.118GWh of electrical energy annually when it becomes operational in 2012.

The electrical energy generated by the plant will amount to 1.1% of the total energy production in Turkey.

The powerhouse will be 20m wide, 126m long and 45m high. The turbines in the plant will be fed with water through a 9m diameter penstock. Water from the turbines will then be exited through 74m long tunnels.

The Deriner double-curvature concrete arch dam

The Deriner dam will be a double-curvature concrete arch dam. It is 253m high from the foundation and 202m from the river bed and has a crest elevation of about 397m. The dam has a concrete volume of 3.5 million cubic meters.

The diversion tunnel is 898.14m long and has a capacity of 1.804 cubic meters per second (cusec).

The overflow spillway has a capacity of 2.25 cusec while the orifice spillway has a capacity of 7 cusec.

Key players in the Deriner dam project

Turkey's State Hydraulics Works (DSI) owns the project. A consortium consisting of ERG Construction, Technopromexport, Stucky, ALSTOM, Sulzer Hydro and Hydro Vevey is responsible for the construction of the project.

The consortium of Poyry (formerly Electrowatt Engineering) and Dolsar Engineering designed the dam and the powerhouse. The consortium is also responsible for providing quality assurance throughout the project. The contract is worth approximately $24m.

Construction work and components of the project

The funding for the project was attained in 1997 and construction began in 1998.

The excavation and construction of the dam's foundation necessitated a diversion of Coruh River, which was completed in 2005. The diversion was done through a horseshoe cross-section tunnel on the right bank.

The Deriner site consists mainly of granodiorite rock with a certain amount of diabase dykes. The decompressed and heavily jointed rocks existent in the upper layer necessitated a huge amount of excavation to be undertaken.

The excavation work was carried out by drilling and blasting using the pre-splitting method. The initial sections of the foundation were, however, excavated using a controlled blasting method. Pre-stressed anchors were used in some cases.

Natural slopes totaling 430m in height from the right bank, 480m in height from the uppermost part of the left bank, 29 berms at the right bank and 33 berms at the left bank were excavated.

Associated infrastructure such as roads, tunnels and bridges are also being constructed as part of the project.

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