Customer: Nek NEK J.S.C, Natsionalna Elektricheska Kompania, Sofia
Construction period: 12.2004 -10.2010
Location: Rhodopen, a mountain range at the border with Greece
Country: Bulgaria
The project is located in the Rhodopen, a mountain range at the border with Greece, and will be part of a string of power stations along the Vacha River. The storage power station will have an installed capacity of 80 MW and a standard production of 185 GWh/year. The reservoir will have a volume of 111 million m3 and will be contained by an arch dam with a height of 125 m. The power station will be located downstream, aboveground on the left bank. The intake water tunnel with a length of approx. 600 m will be driven conventionally and will partly cut across a geologically problematic zone.
Concrete arch dam with flood control dam
With a height of 125 m and a crest length of 457m, the Vacha Valley will be closed off with a double curvature concrete arch dam. The river will be diverted through a 500 m tunnel during the construction period. The public road will run through a 250 m road tunnel in the dam area during the construction period.
Gashnia sealing
An area of approx. 60,000 m² must be sealed off around the intake structure in the Gashnia Valley due to this area’s geological features.
Power house
The power house will be constructed as an aboveground structure. In addition to the intake structure, the intake waterway consists of a 60 m vertical shaft and a 530 m horizontal pressure tunnel with a 10% inclination. Steel lining will be required for the entire intake waterway. The water will power two Francis turbines and flow through a stilling section back into the Vacha River, which will be in the tail rack section.
Technical data
Catchment area: 1,214 km²
Annual inflow: 650 million m³
Average inflow: 69.5 m³/s
Useful inflow: 580 million m³
Reservoir area: 3.27 km²
Total storage: 111 million m³
Max. operating level: < 685 m
Live storage: 41 million m³
Nominal rating: 2 x 40 MW
Min. perating level: 648 m
Power generation: 185 GWh/a
Gross head. 136 m
Type of generator: Francis turbine
Download: ALPINE Folder Tsankov Kamak, EN
