The Karahnjukar Hydroelectric Power Station in East Iceland harnesses two glacial rivers. The complex comprises a rockfill dam as well as several smaller dams, an underground power station and two 400 kV transmission lines, each approximately 50 km long, that supply power to the Alcoa Fjardaal Aluminum Plant.

Technical data:
Client: The National Power Company (Landsvirkjun)
Installed capacity: 690 MW
Turbines: 6 Francis units, vertical axis
Rated capacity: Discharge of 144 m/s at a power of 690 MW
Gross head: Max gross head of 599 m
Karahnjuka Dam: Length 700 m; height 198 m
Water reservoir: Halslon Reservoir; 625 - 575 m.a.s.l.; storage capacity of 2,100
million m³
Headrace tunnel: 40 km, ø7.2-7.6 m
Other tunnels: 11 tunnels totalling 32 km in length, ø6.5-9.0 m
Pressure shafts: 2 vertical pressure shafts; ø3.4 m; length 400 m
Generating capacity: Approximately 4,600 GWh/year

Mannvit services:

• Site investigation
• EIA report
• Assessment of harnessing choices
• Civil works design
• Structural and mechanical design
• Preliminary and final design
• Cost estimates
• Tender documents and evaluation
• Contract documents
• Project planning
• Testing and start-up
• Commissioning
• Site supervision
• Design of the 400 kV transmission lines.