A joint venture led by Mott MacDonald and comprising Línuhönnun, Fjarhitun and HNIT from Iceland plus European companies Coyne et Bellier, SWECO and Norconsult, has been appointed by national power company Landsvirkjun to oversee construction of a 190m high concrete faced rockfill dam and a 60km tunnel in eastern Iceland.
The dam and tunnel are part of a US$1.3B project – the largest industrial development in Iceland’s history – which includes the Kárahnjúkar power station being built to supply energy to US company Alcoa’s new aluminium smelter. The project is being developed to provide a vital injection to the nation’s economy and a life support for the inhabitants of the east fjords.
Development of the Kárahnjúkar power station entails harnessing the glacial rivers Jökulsá á Dal and Jökulsá í Fljótsdal and creating the 57km2 Hálslón water-storage reservoir and the smaller Ufsarlón reservoir.
From the Hálslón reservoir, water will be conveyed through an underground headrace tunnel eastward joining another tunnel from the Ufsarlón reservoir. The water will then be carried in a single tunnel north eastward to the Teigsbjarg escarpment, where it will drop through two steep penstocks to an underground power house. There the water will enter six generating units in the power house and then travel through a tailrace tunnel and canal into the course of the glacial river Jökulsá í Fljótsdal. The hydro power station will have an installed capacity of 690MW, and a power-generating capacity of 4460GWh per year. The dam will be constructed in the Jökulsá á Dal river to create the Hálslón reservoir.
As lead consultant in the joint venture Mott MacDonald will direct the single integrated construction supervision team which will be created and based near the Vatnajökull glacier to supervise construction of the dam and tunnel.
Mott MacDonald will also project manage all dam construction work and will provide specialist expertise for the 7.2-7.6m diameter tunnel – 33km of which will be created using a TBM and the remaining 27km using drill and blast techniques.
It is anticipated that the dam will be completed in late 2006 and the tunnelling by the middle of 2008.