Work included
- Installing upper slope mesh and concrete spraying.
- Installing a lower retaining wall and anchors on the downslope section. Rock in the mid-section was very deep which required long anchors and deep drilling.
- Installing a roadside filter drain.
- Installing Reno (Gabion) mattresses.
- Placing rockfill and constructing the roadside beam, which required an additional 18 anchors because of its length and depth.
- Stabilisation works which included the use of soil nails to reinforce the embankment.
- Installing a new vehicle safety barrier.
How it happened
The embankment supporting the road at the C30 washed away near Kilmaha. The slope is very steep and the material forming the embankment is not particularly strong. Initial stabilisation works were carried out including some rock infill (700 tonnes of rock armour) and soil nailing (large diameter bolts which are drilled and grouted into the ground).
Geological engineering design works enabled work to continue on site while we completed the fine detail which ensured the correct solution, providing long term stability for the embankment.
Access to the site and delivery of materials was challenging. Whilst good progress was made, we were unable to accelerate these works due to logistic challenges and safety requirements. We initially hoped to reopen this route by 10 November but the further safety issues emerging ruled this out.
Image of recently installed soil nails -
Another image of soil nails from further down the slope -
