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Summary

Description

James Williamson (engineer for North of Scotland Hydro Electric Board technical panel), Balfour Beatty and Co. (main contractors), designed 1936, built 1946 onwards. Large buttress dam with access roadway oversailing prominent arcaded buttresses with fixed spillway to centre integrated with buttress and control tower, dominating upper reaches of Inveruglas water. Shuttered concrete, with some reinforced concrete to parapet and gatehouse control tower. Battered downstream face with deep buttresses with rounded headed gaps between. Large buttress to centre forming fixed spillway with central rib integrated with dispersal valve to base and control tower to parapet. Parapet to top with small buttressed piers springing from centre of main buttresses.

TUNNEL INTAKE AND DISPERSAL VALVE GATEHOUSE: set directly adjacent to upstream face of dam on large concrete pier incorporating intakes for tunnel and dispersal valve beneath waterline. Large panelled teak vehicular access doors to SE elevation with paired narrow rectangular windows to SW and NE elevations.

Statement of Special Interest

Sloy Dam forms an A-group with Sloy Power Station (see separate listing). The dam is of a pioneering design and is an excellent example of the work of preeminent designer and engineer James Williamson. It forms a major component of the Sloy Hydro Electric Power Scheme (along with Sloy Power Station), the first to be built by the North of Scotland Hydro Electric Board (NoSHEB). The scheme is in a significant location setting a precedent in terms of design and construction, informing all future work by the Board on the developments of schemes throughout the rest of Highland Scotland. The dam dominates its setting on the upper reaches of the Inveruglas Water and the bold use of striking functional yet modern design illustrates the confidence of NoSHEB and the strength of their vision for the development of Hydropower in Scotland.

The Sloy scheme was the first of the major post-war hydro electric developments by NoSHEB, with this second phase of development dating from the mid 1950s. The scheme played a key role in the realisation of the social agenda of NoSHEB by providing power which could be exported via the grid to the central belt (via a connection at Windyhill near Glasgow in the case of Sloy), the profit from which subsidised the provision of power to remote north highland communities and stimulated economic regeneration. Under the leadership of eminent chairman Sir Tom Johnston the board undertook developments throughout highland Scotland and his aspirations saw the development of schemes in locations such as Loch Dubh near Ulapool and Storr Lochs on Skye. Johnston's social aspirations and wider wishes to reinvigorate the economy of the Highlands ensured that schemes in remote areas formed a key part of the NoSHEB development plan.

All of the developments carried out by NoSHEB were subject to parliamentary approval and objections on the grounds of scenic amenity were common. In order to meet these objections the board appointed a panel of architectural advisers which included Reginald Fairlie (1883-1952), James Shearer (1881-1962) and Harold Ogle Tarbolton (1869-1947), appointed in 1943. Initially the role of the panel was to adjudicate on competition entries for designs, but by 1947 it had become one of designers. The panel had little control over the functional form of the buildings, as they left this to engineers, but they did influence the appearance and the style of the designs. The design of Sloy Power Station is typical of Harold Ogle Tarbolton's bold designs for NoSHEB as can be seen in his work at Pitlochry and Clunie (see separate listings). This contrasts with the later approach of the board after Tarbolton's death in 1947, with the focus on the integration of buildings with the landscape with the use of natural stone and rubble facings.

The design of Sloy Dam would go on to typify James Williamson's approach, with an innovative solution designed specifically to suit the requirements of a particular site. His design for Sloy Dam was pioneering. He had first described the principal of using buttresses instead of mass concrete in 1936 when lecturing in Washington DC. The use of this technology represented a significant cost saving for the Board with only 20,000 tons of concrete required for construction, in contrast to the 50,000 which would have been necessary for a conventional mass concrete dam. Williamson was a prominent engineer who specialised in the design of dams following his work on the Galloway Hydro Electric scheme (see separate listings) in the 1930s. He acted as one of the chief engineering advisors to NoSHEB and was the lead engineer for a number of schemes until his death in 1953. After this date his company, James Williamson and Partners, continued in the role of chief engineers to the board.

Previously listed with Sloy Power Station. Now split and category changed from A to B as part of Hydro Electric Power Thematic Survey 2011.

References

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