The 690 MW Karahnjukar Hydroelectric Project harnesses two glacier rivers originating in the Vatnajökull Glacier. The larger river, providing about 2/3 of the flow to the plant, is dammed at the Karahnjukar Mountain with the 198m high Karahnjukar concrete face rock fill dam and two moraine core rockfill saddle dams, 69 m and 25 m high. With the three dams the 2100 million m3 storage reservoir is created with the maximum supply level at 625 m a.s.l. From the reservoir a 40 km long headrace tunnel was excavated, mainly with 3 tunnel boring machines, to a 420 m high pressure twin pressure shaft, feeding six high head Francis turbines in an underground powerhouse. A 1 km long tailrace tunnel leads the turbine water to the Fljotsdalur valley at an elevation of 25 m a.s.l.
The second river is dammed at an elevation 625 m a.s.l. and the water fed into the headrace tunnel with a 13 km long diversion tunnel. In addition, there are some diversions with smaller dams and tunnels.
The total cost of the project is about 2 billion USD. Construction started in 2003 and the units came online in November 2007. The annual generating output is around 4.8 TWh.
The services included overall project management of the project including from site investigations, an environmental impact assessment, permitting, tendering, supervision of construction management, budgeting, cost control, reporting and commissioning.