Laggan Dam

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Laggan Dam
LagganDam1.jpg
Laggan Dam
Official name Laggan Dam
Location Scotland
Coordinates 56°53′23″N 4°40′24″W / 56.88972°N 4.67333°W / 56.88972; -4.67333Coordinates: 56°53′23″N 4°40′24″W / 56.88972°N 4.67333°W / 56.88972; -4.67333
Opening date 1934
Dam and spillways
Impounds River Spean
Height 48 metres (157 ft)
Length 700 feet (210 m)

Laggan Dam is a dam located on the River Spean south west of Loch Laggan in the Scottish Highlands.

History[edit]

The structure was built by Balfour Beatty for the British Aluminium Company and construction was finished in 1934. The supervising engineers were the firm of C S Meik and William Halcrow, now known as the Halcrow Group.[1]

The dam was designated a Category B listed building in 1985. It was upgraded to Category A listing in 2011, following a review as part of Hydroelectric Power Thematic Survey 2010.[1][2]

Design[edit]

Water flowing over the spillway and the pipes in the centre of the dam

The dam is about 700 feet (210 m) long,[3] and 48 metres (157 ft) high between the level of the foundations and the crest of the spillway.[4] It is curved upstream like an arch dam with a radius of curvature of 2,000 feet (610 m), but works purely on the principle of a gravity dam.[5]

The whole crest of the dam, except for a section in the middle that houses equipment, is a spillway broken into 29 bays by piers that support a roadway across the dam.[4] As well as the spillway, there are six pipes embedded into the centre of the dam, controlled automatically by system of air valves.[4] The foundations are built on granite, and the dam was built in seven sections, with copper strip and hot poured asphalt water stops in the joints.[4]

The dam contains Loch Laggan, which has a capacity of 40,000,000 cubic metres (1.4×109 cu ft).[4]

Water from the dam is conveyed to Loch Treig through 3 miles (4.8 km) of tunnel. From there, the waters travel through a further 15 miles (24 km) of tunnel 15 feet (4.6 metre) in diameter, before descending the hillside to a power house at Fort William through five steel pipes. The dam can be found next to the A86 road from Fort William. The catchment area of the dam was increased by an aqueduct which can be seen at the side of the road in Strath Mashie.

References[edit]

  1. ^ a b "Listed Building Report - Lochaber Hydroelectric Scheme And Aluminium Smelter, Loch Laggan Dam". Historic Scotland. Retrieved 30 August 2013. 
  2. ^ "Record Details - Loch Laggan Hydro Electric Dam". Highland Historic Environment Record. Highland Council. Retrieved 30 August 2013. 
  3. ^ International Commission on Large Dams (1936). "Transactions": 79. 
  4. ^ a b c d e Wallis, R. P.; Morison, A . C.; Gunstensen, R. Remedial drainage to Laggan and Blackwater gravity dams (PDF) (Report). 
  5. ^ "Laggan Dam". International Commission on Large Dams of the World Power Conference. 1964: 145. 

External links[edit]