Preventing a path from disappearing into a burn

by | Jul 1, 2024 | Conservation, Green engineering, Projects

We had a nice wee job to do today to protect the riverside path along the Muck Water at Dalmellington in the Doon catchment where there’s always a steady stream of walkers. I’m pretty sure the landowner once told me that over 60,000 people a year walk this path. I think there’s a counter that records footfall buried somewhere under the path. Anyway, this stretch of the Muck Water was man made back in 1916 when the burn’s course was realigned to accommodate an aerial gunnery school built just a couple of hundred metres away.

Delivering materials on Saturday to the job site ahead of the repair this morning. The dam in the foreground backed up water and we removed this as it had been built recently by kids. We used the boulders to support the toe of the bank

The edge of the path had eroded over a short stretch where the river had taken away some previous bank engineering during large spates. A biodegradable reinforced plastic netting had been used but failed. The original work was performed by a contractor back in 2016 around the time that ART also worked on the burn to increase juvenile salmon and trout numbers. I suppose failures are to be expected to a certain extent when working in and around rivers but that’s why we advocate the use of living materials such as willow so much. Once established willows can dramatically reduce unwanted erosion.

Struan and Cameron after placing the Sedimats in the river beside them at the start of the job. These specialist mats trap mobilised sediments preventing damage downstream. As we weren’t working in but near water, we felt this belt and braces approach was more than adequate. We expect other contractors to take care working around water so its important that we use best practice too

However, at the water’s edge and toe of the bank, things appeared to have stabilised so it was really just to protect the path that we intervened. The landowner was concerned that the path may be lost completely or someone may slip off the edge. We place a few boulders into the toe of the bank that we removed from a small dam built by local kids, then drove long, stout willow stakes into the foot of the stable bank, back from the water’s edge and through brash bundles. Behind this we filled the edge of the path with willow branches and more brash and these were also staked in place with live willow materials. All these stakes should root and sport shoots in time which will give the bank a fair degree of buffering and protection during high water as they grow. As the shoots grow into bushes and trees, any threat of erosion in future should reduce.

With a larger machine than really necessary, we could reach across this burn without damaging the bed. In this image we were driving the posts into the bank using the machine.  

Laying sods dug from the far bank away from the water, across the stream to finish off the bank top. This vegetation will maintain the edge to the path and quickly knit the bank top together. Directly below the soil was fresh cut willow and brash bundles and they were all staked in place.

On top of  the brash and fresh cut willow we added soil and vegetation (sods) excavated from rough ground away from the water on the opposite bank. We managed to do this by reaching across with the machine to drop this in place. We hired a larger machine than was really necessary to allow us to have the extra reach to stay out of the river. Our thanks to Jock Paterson of Kirkoswald for a virtually brand new machine with only 70 or so hours on the clock! That was a bit of a treat.

We did have to cross the burn once and back to do this but we did that at the shingle upstream of the work area where the machine hardly wet its feet. With Sedimats in place as a precautionary measure, to trap any mobilised sediment when we crossed, we were confident we could prevent any damage downstream. The vegetation was obviously a bit damaged on the bank where we worked to transfer the soil across by the tracks of the machine as it moved about but will recover quickly. All in all, this should prevent the river taking the path away in high water again and the entire bank face should soon have a mixture of natural vegetation and a healthy crop of willows growing along it that will prevent any further chance of failure. Fingers crossed it work out wellWe will provide an update in a month or two after the vegetation has removed and things have settled into place.

The finished repair