Afon Gwydol, Abergwydol, Mid Wales
Client: Carillion Rail for Network Rail
Project Brief: Works were required to repair an eroding railway embankment adjacent to the river. This resulted in the embankment encroaching into the river, causing erosion problems on the opposite bank belonging to a local farmer. Difficult access created problems for using stone.
The Solution: Replace part of the blockstone armouring with North American Green (NAG) P550. The NAG P550 is the highest performing composite Turf Reinforcement Mat (TRM) in the UK. Compared to blockstone armouring it is also a more environmentally sustainable, cost effective solution that was easier to install. It also blended in better with the environment. Anchor trenches were dug at the toe and the top of the slope to ensure the NAG P550 was not washed away during the winter floods. Under Salix supervision, Carillion Rail dug the trenches and formed the slope ready for Salix site operatives to seed the area with a specialist river mix and manually install the NAG P550. The area was also over planted with some wetland plants.
The Result: The works were carried out at the end of October, which meant that the NAG P550 remained only partially vegetated throughout the winter months of frequent flooding. By the end of the following Spring, there was no soil erosion and a good rate of vegetation establishment.
Materials used: NAG P550 Wetland Plants
NAG P550 being installed over a prepared
surface. A specific riverbank seed mix is sown
prior to rolling out the NAG P550 over the top
Blockstone toe holds NAG P550 in place and
prevents undercutting
NAG P550 partially vegetated in November, 1
month after installation at the end of October
March - successfully established reed plug planting in to NAG P550
