Karahnjukar hydroelectric project
The Kárahnjukar hydroelectric plant, located approximately 90 km southwest of the city of Egilsstadir, in the eastern part of the country, is the most important project currently under construction in Iceland. The main purpose of the project is to collect the glacier waters of the Jokulsa a Dal river in the Halslòn reservoir, for subsequent transfer to a 690 MW underground powerhouse. The electric power generated will be used to run Iceland’s largest aluminium production plant (more than 350,000 t/y).
The concrete-faced rockfill dam is 193 m high, with a crest length of approximately 730 m and a rockfill volume of 8.5 million m³.
The river diversion works comprise two tunnels with lengths of 764 m and 845 m respectively, excavated using traditional methods. The bottom outlet consists of a 60 m high, 5 m diameter surge shaft, discharging into one of the two diversion tunnels.
The headrace tunnel is approximately 39 km long, of which a section of 35.3 km excavated using three full-face TBMs, two with a diameter of 7.20 m and the third with a diameter of 7.60 m; the remaining 3.7 km section was excavated with traditional methods. Additionally three adits will be excavated, as well as a secondary headrace tunnel and drainage tunnel (overall length 16.6 km) and two valves chambers for a total volume of 13,425 m³.
| MAIN TECHNICAL DATA: |
|---|
| Dam rockfill embankmen: 8,455,000 m3 |
| Concrete works: 178,050 m3 |
| Underground excavation works: 2,300,000 m3 |
| Underground concrete works: 50,850 m3 |