Lochaber Hydro-Electric Power Scheme

Water pipes of the Lochaber Project at Fort William
©2022 Gazetteer for Scotland

Water pipes of the Lochaber Project at Fort William

A hydro-electric scheme of the SW Highland Council Area, the Lochaber Scheme is closely associated with the Aluminium Smelter at Fort William, which takes the majority of the power. Constructed in three phases between 1924 and 1944 for the British Aluminium Company, the scheme harnesses the Rivers Mashie, Pattack, Spean, Spey and Treig, together with a number of smaller rivers, benefiting from the exceptional rainfall in this area. It was the work of civil engineers Charles Meik (1853 - 1923) and William Halcrow (1883 - 1958), with the electrical generation designs the responsibility of William McLellan (1874 - 1934).

The uppermost part of the scheme is located 9 miles (14.5 km) west southwest of Newtonmore and was completed with the help of Canadian troops in 1943. It involves the Spey Dam and Reservoir, a canal link to Loch Crunachdan and a tunnel conveying the water to Loch Laggan. Constructed in 1931, the Laggan Reservoir (Loch Moy) is contained by a 274-m (900-foot) long and 40-m (131-foot) high dam, which is linked by a 2¾-mile (4.4-km) long tunnel to Loch Treig, another large reservoir contained by the Treig dam.

The culmination of the scheme is a 15-mile (24-km) long and 4.5-m (15-foot) diameter conduit, the first part of the scheme to be built and a major feat of engineering which was for 50 years the longest water-supply tunnel in the world. This tunnel was the responsibility of Balfour-Beatty and was begun in 1926. It runs from Loch Treig, collecting further streams and rivers at intakes along its route, to emerge from the side of Ben Nevis at a 9.14-m (30-foot) wide and 73m (240-foot) deep surge chamber, which leads to five enormous steel pipes that descend from a height of 182m (600 feet) into the power-house of the Lochaber Aluminium Smelter. The smelter was established in 1929 and remains a major employer in the Fort William area. It uses approximately 95% of the 65 megawatts (MW) of generation capacity of the hydro scheme to reduce imported aluminium oxide to aluminium metal, with the excess power sold to the National Grid for the public electricity supply. The water is discharged through a half-mile (1 km) tailrace into the River Lochy.

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