Valve Gatehouse, Loch Sloy Dam, Sloy Awe Hydro Electric Scheme, Arrochar, Argyll and Bute

Description

Harold Ogle Tarbolton (architect for the North of Scotland Hydro Electric Board architectural panel), 1950 (designed 1947). 2-storey, 5-bay rectangular-plan classical modern power station with additional lower office block attached to left (SW). Prominent full-height pre-cast pilasters to SE turbine hall elevation. Steel frame with pre-cast Rubislaw and Corrennie granite slabs. Banded corniced eaves course with deep blocking course above.

SOUTH EAST (PRINCIPAL) ELEVATION: roughly 11 bays with tall 6-bay turbine hall to right (NE) and lower range to left (SW) comprising offices and store. Slightly advanced 4-bay centre to turbine hall flanked by single outer bays (that to right (NE) blank) with giant order pilasters with dentilled capitals dividing bays, all oversailing tailrace on concrete piers and segmental arches. Full-height rectangular windows to ground floor in moulded concrete surrounds carried beneath banded cill course; smaller windows above in narrow moulded surrounds. 4 full-height windows to lower section at left (SE) with cantilevered concrete balconies and doorways above; similar to single bay return. Slightly taller recessed single bay to far left (SE) with similar windows.

SW (ENTRANCE) ELEVATION: 3-bay advanced entrance block flanked by single recessed bays. Advanced doorpiece flanked by rectangular windows at ground with balcony above incorporating North of Scotland Hydro Electric Board coat of arms. Tall rectangular window at 1st floor with moulded architraved surround. Similar windows and balconies to those at office block to SE elevation.

NW (REAR) ELEVATION: similar to that at SE with advanced panelled teak vehicular access door in plain surround and transformer station directly adjacent to rear of turbine hall elevation and roughly 4-bay advanced workshop to right (SW).

NE ELEVATION: 2 symmetrical bays with full height windows at ground floor and smaller rectangular windows above.

Predominantly small pane windows with some hopper top openings in painted Crittal frames. Flat platform roof, behind parapet. Cast-iron rainwater goods with decorative hoppers.

INTERIOR: full-height entrance vestibule with dog leg stair on axis with door giving access to balcony at 1st floor; octagonal section pillars all in polished marble with marble tiles to walls. Various offices and store rooms with main control room directly opposite entrance door at 1st floor retaining original control panels (2009). High quality fixtures including stair handrails and some oak doors with brass handles. Predominantly plain functional interior to turbine hall with large travelling crane to gantry at attic level and trussed steel roof structure.

Statement of Interest

Sloy power station forms an A-group with Sloy Dam (see separate listing). Sloy power station is the earliest example of the work of the North of Scotland Hydro Electric Board (NoSHEB) in the development of hydro electric power in Scotland. It is a bold Modernist Classical design, sited in a prominent location on the banks of Loch Lomond adjacent to the A82 trunk road and is a fine work by one of the board's most significant architects, H.O.Tarbolton. The station is an integral component of the Sloy Hydro Electric Scheme, which also included Sloy Dam (see separate listing), and was the first major scheme to be developed by NoSHEB after its inception in 1943. The scheme was highly significant as the precedents which it set in terms of design and construction informed all of the future work by the Board on the developments of schemes throughout the rest of Highland Scotland. The scheme was highly ambitious in scale and technology and the generators had the highest capacity of any in Britain when they were installed.

Sloy power station is a prominent example of the bold modernist phase of designs by NoSHEB and the use of modern materials such as pre-cast concrete blocks expressing the dynamism of the industry at this time. The board also aspired to creating a new prosperous society in the Highlands by bringing electricity to remote communities. The station was the first to be built by the board and the bold design was part of a conscious effort to shape the wider agenda in the energy sector and to clearly characterise, through architecture, the aims and ideals of the revolution it felt it was bringing to Scotland.

The power station was designed with 4 turbines commissioned from the English Electric Company, with a combined generating capacity of 160 megawatts, at the time the largest in Britain. The station has a large head of 277 metres with water conducted via aqueduct tunnel and pressure pipeline from Sloy Dam (see separate listing). The average output of the station is 130 million units. The turbines were refurbished in 1999 as part of a wider program of redevelopment at the station costing £113 million and designed to keep it in operation for the next 30 to 40 years.

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, 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 Ullapool and Storr Lochs on Skye. Johnstone'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.

Harold Ogle Tarbolton became involved in the design of hydro electric infrastructure for NoSHEB late in his career (he died in 1947), but he had been a member of the Amenity Committee which considered the work carried out under the Galloway Water Power Act of 1929, acting as advisory architect for the Galloway schemes and designed the associated housing schemes. As a consequence of his experience in Galloway and his original training as a civil engineer he was appointed to the North of Scotland Hydro Electric Board alongside James Shearer and Reginald Fairlie. His two most prominent commissions for the power stations are those at Loch Sloy and Pitlochry (see separate listings). Both of these designs are characterised by confident use of modern classicism and bold application of pre-cast concrete panels.

(List description updated 2011 as part of Hydro Electric Power Thematic Survey)

External Links

Historic Environment Scotland Listing

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