RAFTS, in partnership with SEPA’s Water Environment Fund and Galloway Fisheries Trust has project managed the removal of a large, disused weir close to Twynholm in Dumfries and Galloway which was completely impassable to fish. The following photos tell some of the story:
The weir was a very significant structure that was built between 1850 and 1890.
A disused sluice gate leading into a culvert not far downstream of the weir was also problematic for fish, and so job number one was to remove this and widen the gap at the downstream end….
Then it was on to removing the weir. The first step was creating an area dry enough to enable sediment removal upstream of the weir. This was achieved by overpumping, and careful sediment control measures were employed. For the first time in well over 100 years, the weir was dry.
Sediment was carefully removed, drained, sorted (with reusable material retained) and then disposed of at a licensed facility.
When expert opinion determined that the original bed level had been reached, the weir was removed and the task began to create rock steps (using material won from the demolition) which would ensure channel stability, guarding against incision and erosion as well as creating a riffle-run-pool sequence to replicate original channel condition.
Pre-seeded coir erosion control blanket (matting) will be used to assist with re-vegetation and bank stability.