Building the Lochaber Factory
The scheme was initially designed by engineer Charles Meik but after his death in 1923, the scheme’s realisation was left to William Halcrow, by then a partner in the firm founded by Meik’s father Thomas Meik.
The project was finally sanctioned by Parliament in 1921, but construction did not start until 1924. On 30 December 1929, the first aluminium was cast. It took about 95% of the 82,000 kW of power generated. It eventually became part of British Aluminium.
Loch Treig dam
The scheme harnessed the headwaters of the Rivers Treig and Spean and the floodwaters of the River Spey (plus a further eleven burns along the way). The Laggan Dam (213 m long and 55 m high) contained the flow of the Spean in a reservoir. A 4 km tunnel then linked this body of water with another reservoir (Loch Treig) contained by the Treig dam. From here, the main tunnel, until 1970 the longest water-carrying tunnel in the world, at 24 km (15 miles) long and 5 m in diameter, was driven around the Ben Nevis massif. From the western mountainside, down five massive steel penstocks, the water was channelled to the turbines in the power house at the smelting plant.