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Fri January 28 2022

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Air jetting used to excavate rare tree

1 Jul 16 Tree surgeons working for Costain have used air jetting to transplant a rare tree, complete with seven-metre roots, on a Welsh road scheme

Carefully extracting the roots of the Welsh Whitebeam
Carefully extracting the roots of the Welsh Whitebeam

The Costain team working on the A465 Heads of the Valley dualling scheme in south Wales needed to relocate a Welsh Whitebeam (Sorbus Cambrensis).

The solution to retaining the roots was pneumatic soil excavation – an AirSpade – a handheld tool that fires a jet of compressed air into the soil structure.

There are thought to be fewer than 100 Welsh Whitebeams in existence. Distinguished by the white undersides of their leaves in summer and red berries in autumn, they are all in the Brecon Beacons National Park. Two are located within the corridor of the A465 scheme, with one on the footprint of the new alignment.

The tree’s age meant a successful transplant depended on retaining as much of its root structure as possible. However investigations led by environmental consultant RPS and  tree surgeon GT Jones revealed that soil conditions around the tree’s lower roots were largely unknown, making it difficult to predict the shape and extent of the tree’s roots.

The AirSpade was used to cut through the soil quickly and accurately, enabling the team to remove and break up the soil without any damage to the tree’s root system. A root mass extending laterally up to seven metres was removed without any damage.

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