Lochaber Hydro-Electric Station
1921 After many years of study and debate, Parliament sanctioned the building of a new aluminium factory with its own hydroelectric installation harnessing the power of the Rivers Treig and Spean and the flood waters of the River Spey.
The construction was carried out in three stages extending over many years:
- Stage 1 involved feeding the waters through a concrete lined pressure tunnel and through steel penstocks to a power station. The main tunnel, 5m in diameter for 24km, was driven through the massif centred on Ben Nevis and was the longest water-carrying tunnel in the world at the time.
- Stage 2: water storage was provided by the construction of the Laggan Dam, an arch-gravity dam 213m long and 55m high on the River Spean. From this reservoir the water was conveyed through a 4.5m tunnel to Loch Treig, the level of which was raised 11m by building Treig Dam, a rock fill dam with an impervious concrete core. From Lock Treig the water was conveyed to the Power House with a total output of 72 megawatts.
- Stage 3: A composite dam 378m long and 18m high was built across the River Spey, to divert the flood waters of the Spey through a conduit and yet another tunnel which fed water into the eastern end of the Loch Laggan reservoir.
At the peak of construction over 3000 men were employed on the Lochaber project
The station had a total installed capacity of 88MW.
Sources of Information
- Halcrow Group