19/10/2026
Anchored Sheet Piling Where the Rock Says No
Sheet Piling (UK) Ltd has completed the sheet piling for a permanent anchored retaining wall at Tarmac’s cement works in Dunbar, working for main contractor Pyramid Construction Scotland Ltd as part of the Limestone Addition Project at the site. Installation of the ground anchors that hold the wall is now under way.
The wider scheme provides new silo and conveyor foundations. Our scope covers around 35 linear metres of permanent sheet piles together with tension pile anchorages securing the sheet piled wall in place.
Limestone bedrock shaped the entire design. A sheet pile wall normally takes its stability from the embedded length below excavation level, with the ground beneath the excavation doing the work that keeps the wall standing. At Dunbar the rock allowed only nominal embedment, so that mechanism was not available to us. The wall could not hold itself, and the load had to be taken somewhere else.
The answer is three levels of permanent tension pile anchorages rather than one. Fifty-six self-drilling anchors, each around 15 metres long, will tie the wall back into competent rock at top, middle and bottom levels, with every anchor tested to 110 per cent of its safe working load. Anchoring at three levels means returning to the wall as the excavation advances rather than completing the works in a single pass, which makes the job a sequencing exercise as much as a piling one.
Installation was by conventional gated methods rather than a telescopic leader rig, using a Liebherr LR1160 crawler crane supplied by Weldex. Driving into rock asks more of a pile than driving into soil, and a gated system holds the pile in position while it is being driven. Leader rigs have taken over much of the industry’s work, but on rock in a confined space the gated method still earns its place. The working area at the plant is tight, and the gate arrangement was developed around what the site allowed rather than what would have been convenient. Weldex operate from Muir of Ord in the Highlands, so the lifting capacity on this Scottish project came from a Scottish supplier.
The piles were EMSTEEL Group GreenSheetPile™, produced using recycled scrap and 100 per cent renewable energy, and supplied from our extensive UK stockholding.
Small schemes are not always simple ones. Thirty-five metres of wall is a modest quantity by most measures, but the combination of limestone rock, three anchor levels and a live industrial site makes this one of the more involved pieces of design work we have delivered this year. Scotland has a single cement plant, and keeping it running while it is extended is a constraint every element of the design had to respect.
