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Large Wooden Structure (LWS) Installation and River Restoration

Edwin Third, Dee District Salmon Fishery Board
River Gairn, River Muick and Garbh Allt burn.

River Gairn & River Muick

Between 2019 and 2021, we have completed four river improvement projects for Edwin Third of the Dee District Salmon Fisheries Board under the design supervision of Hamish Moir from cbec.

Improving River Gairn and River Muick involved installing approximately 80 large wooden structures. The trees used had 9m long stems, with the root plate still attached. For around 60 of these structures, the 100+ trees required came from off-site and needed to be transported by road in artic lorry tipper trailers, before being transported to the remote site on tractor trailers. The rest of the structures were built with trees sourced from an adjacent area to the installation site.

The client and designer put emphasis on the desire to keep the root plates as intact as possible to maximise their benefits. To achieve this, we deployed their Engcon and grapple-equipped excavators rather than a standard excavator bucket to carefully load, unload and place the stems and plates, so they arrived in the river with minimal damage.

An excavator felling trees at River Muick

Garbh Allt Burn

The Garbh Allt burn site on the Balmoral Estate required us to remove five artificial embankments and excavate to open four artificially-closed secondary channel entrances.

The excavated material was processed with a screener and the desired size of aggregate was transported to two sediment introduction sites upstream. The balance was landscaped into natural contours locally or taken to an old borrow pit for use by the estate in the future. This involved excavation, processing, and deposition of approximately 800 cubic metres of river gravels, including a portion of boulders.

These sites required sediment curtains, oil booms and machinery access across peat and soft ground. Our tracked excavators tread lightly, and our experienced operators reinstated track marks with spot turfing to help facilitate quick re-vegetation. Our investment in a large Mooroka tracked dumper allowed us to bring 60 trees approximately 300m across a peat bog with minimal ground disturbance and repairs.

A CRC Dumper in the foreground transporting felled trees with a CRC branded vehicle in the background

Our Experience

Through working on these four cbec-designed sites, our site and management team have built an effective working relationship with Hamish Moir and have a good understanding of the Field Fitting requirements that are often required in this type of work.

Our operators are used to working in upland, remote locations and have extensive experience of operating machinery sensitively and safely in locations. By taking a flexible, proactive approach, these sites were completed to a high standard with minimal environmental damage to the surrounding area.

A CRC excavator working on a river bank

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