Stonebyres hydro-electric power station, Lanark

Photos: Drax

When thinking of conservation projects, power stations rarely come to mind, but Stonebyres hydro-electric power station is nearly a century old and was in need of some repairs.

It’s one of two buildings that make up the Lanark hydro-electric scheme on the River Clyde in Scotland. The art-deco building is designated as a site of national architectural importance and was originally designed by Buchan & Partners. Along with Bonnington power station, they are the oldest hydro-electric stations in the UK electricity industry. Since automation in the 1970s, Stonebyres has been capable of generating 6MW of electricity and together the power stations provide renewable electricity for 17,000 homes.  

As with many old buildings, the power station requires care and maintenance. With the location being so close to water, moisture had exacerbated some of the problems. Since Drax Group acquired the hydro scheme two years ago, a £1.1m programme of restoration work has been put in place.  

Drax enlisted the help of a restoration consultant, Bob Heath of Heath Architect and Stone Consultant, as well as liaising closely with South Lanarkshire Council (SLC) regarding the materials and finish. The works were awarded to Zenith Structural Access Solutions. 

The project included replacing all the original windows and renewing any perished materials with modern, stronger materials which had to comply with conservation requirements.

Buildings of this type of construction can suffer from damage where encased internal drainpipes leak. Water damage to steel reinforcement can cause cracks and spalling can occur in surrounding concrete. To assess which products would be best for this type of project, Saint-Gobain Weber was brought in to provide a conditional survey and advise on the most appropriate systems to repair the building.

“The whole project took around two years to complete with around a year spent planning the restoration,” explains Anne Kerr, Drax Group’s senior civil engineer. “We had lots of technical assistance from Weber who visited the site and helped us select the correct products.

The refurbishment

To make repairs to the concrete structure, webercem HB30, a Class R3, polymer modified, high build repair mortar was specified along with webercem fairing coat to infill surface imperfections. Breathability was a key requirement to avoid further moisture building up in the future. Weber recommended that a single coat of webertec aquapel crème was applied to the external walls making them highly water repellent protecting against absorption of water, avoiding carbonation and chloride ingress. The final coating specified was webersil P, a silicone enhanced masonry paint to provide a breathable, hydrophobic and low maintenance finish in the colour of the original building.

Weber was subsequently brought in to work on the restoration of Bonnington Power station further along the River Clyde.

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