Customer: DSI, Devlet Su İşleri Genel Müdürlüğü, managing board for the national hydropower stations
Construction period: 02.2002 – 12.2009
Location: Ermenek
Country: Turkey

Entire project
The Ermenek power station above the Kayrektepe power station (planned) and the Gezende power station (in operation) is the Group’s third and largest project. The 210 m wall dams up the river, the reservoir has a capacity of 4,600 million m³. The catchment area encompasses roughly 2,300 km². The crest of the dam is located at a height of 700 m above sea level. The power station: the water dammed up by the dam flows through an intake structure at a height of approx. 660 m and is conducted
to the power house through an 8 km intake tunnel, a 600 m inclined shaft and a 500 m horizontal section. The power house will be built aboveground on the banks of the Erik River at a height of 350 m above sea level. The gross head will be approx. 350 m. The power station will be equipped with 2 Francis turbines with a capacity of 160 MW each, the annual power generation is calculated to be 1,100 GWh. The Erik stream is collected at a height of 834 m and conducted through a 4 km diversion
tunnel to the Ermenek intake tunnel. The potential of the larger difference in height will be processed in a small underground hydroelectric power station by 2 turbines having 3.4 MW each. The concrete dam: with a height of 210 m and a crest length of only 123 m the extreme gorge will be dammed up with a concrete volume of only 270,000 m³. The river will be diverted through two tunnels having a diameter of 6.5 m during the construction period.

Ermenek pressure tunnel
The 8 km tunnel will be driven from downstream via an access tunnel using a tunnel boring machine, diameter 6.6 m. The geology mainly consists of lime and sandstone in this area. Two areas will cut across flysch zones with a pronounced fault. The first flysch zone is located at the beginning of the heading. The second zone, classified as difficult, is located at driving kilometer 7. Further geologic tests will be performed to decide whether this area must initially be driven by means of a conventional drift.
The pressure tunnel is designed with a surge tank at the lower end, to be constructed as a shaft with a height of 140 m and a diameter of 10 m. A valve chamber in which a shutoff unit will be installed, will be located immediately behind the surge tank. This valve chamber can be accessed via the access tunnel, through which the pressure tunnel will also be driven. After the valve chamber the intake waterway continues into a relatively flat inclined shaft with a length of 600 m and an inclination of 50 %, arriving at the outlet to the power house after passing through a 500 m horizontal section. The geology at this last section should entirely be composed of lime. Flysch zones were assumed to lie above and below the shaft, although they should not reach the shaft itself. The entire pressure tunnel from the intake structure to the surge tank will be lined with concrete with an inner diameter of 5.6 m, the inclined shaft and the lower horizontal section will be armored with steel lining.

Erik pressure tunnel
This work will include a water catchment, designed as a 24 m high weir. The weir will have an overflow spillway , bottom outlet and an intake structure. The pressure tunnel has a length of 4,150 m, an inner diameter of 3 m and an outer diameter of 4 m. This tunnel will also be driven from downstream with a tunnel boring machine. At the end of the tunnel the tunnel will lead into an armored shaft with a height of 180 m. An aboveground surge tank will be positioned above the shaft. An armored horizontal section will lead from the toe of the shaft to the 33 m long and 15 m wide underground power station, accessible via an access tunnel. The processed water will be conducted into a connecting gallery in the valve chamber, from where it is delivered to the Ermenek pressure tunnel.

Ermenek power house
The power house will be built as an aboveground structure. The dimensions of the power house will be 56 m length, 32 m width and 41 m height

Technical data
Energy-economical data for the reservoir
Catchment area: 2,304 km²
Annual inflow: 1,332 million m³
Average inflow: 42.3 m³/s
Total storage: 4,582 million m³
Reservoir area: 61 km²
Live storage: 1,747 million m³
Max. operating level: < 699 m
Nominal rating: 2 x 151 MW
Min. operating level: 660 m
Power generation: 1,014 GWh/a
Gross head: 350 m
Type of generator: Francis turbine