C30 West Loch Awe - road repairs

The C30 West Loch Awe road near Kilmaha is currently closed. Communities can gain access from either end but are unable to travel through. The diversion is A816 - A83 - A819 - A85 and vice versa.

Current situation

  • The upper slope mesh is installed and concrete spraying is planned for next week.
  • The lower retaining wall is complete and Reno (Gabion) mattresses fully installed. Work is ongoing on placing rockfill and constructing the roadside beam. 
  • Anchors are installed for the beam and the foundation is in place.
  • Installation of the vehicle barrier, which we hoped would be done w/b 27 May, was delayed by weather and rebar delivery. It's now booked for w/b 10 June.
  • This sets the completion date to week ending 14 June and, as always, the remaining concrete works are weather dependent, although the improvement in the weather has been helpful.

Last updated: 31 May

Previous updates

  • We are progressing with stabilisation works which include the use of soil nails to reinforce the embankment
  • We’ve installed 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. The upper slope mesh and the roadside filter drain have been installed.
  • We expected work to be complete by the end of March. However, once the detailed design for the roadside beam was confirmed, the length and depth of the roadside beam meant we required an additional 18 anchors. 
  • The upper slope mesh has been installed and is 90% complete, with exception of a cascade area - due to current water levels on the slop. Concrete spraying will be undertaken when a suitable weather window arrives (not too cold and/or wet). The roadside filter drain has been installed. The construction of the lower retaining wall is well underway, digging out is complete, blinding is in place, shutters constructed, steelwork is complete and concrete pouring of concrete started today on 12 April.
  • As these works are weather dependent, and the weather has been poor, completion is anticipated by mid-May 2024, slightly longer than anticipated. We had hoped to be finished by the end of April.

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.

Communities can gain access from either end but are unable to travel through. 

The diversion is A816 - A83 - A819 - A85 and vice versa. 

Image of recently installed soil nails - 

Image
Recently installed soil nails - C30 West Loch Awe

Another image of soil nails from further down the slope - 

Image
Soil nails further down the slope at the C30 West Loch Awe

 

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