Scottish Trunk Road NMC - North West - A85 Allt Na Deabhtaich Wall

Description

The existing Allt Na Deabhtaich retaining wall is a mass concrete retaining wall with random rubble masonry façade situated above the A85 Trunk Road, retains soil slope on the RHS at Glen Ogle. It is approximately 35m in length with a maximum height of 2.8m. The structure is in poor condition with significant defects. The works are proposed to be carried out in 2026 to replace this old structure with a new concrete wall. Scope of the works will include: Demolish the existing retaining wall Install sacrificial passive anchors and testing Cut back the existing slope to 75 degrees to horizontal using top down construction method Open hole drilling and ground anchorages installed Construct new concrete facing by use of sprayed concrete and reinforcement mesh Install new VRS in the front of new structure Construct two small culverts under the A85 at either end of the site extent. Programme Constraints: The Contractor must programme to demolish the existing wall before October 1st 2026. Principal quantities: Take down existing masonry façade 20m³ Demolition of concrete retaining wall 100m³ Excavation and disposal of soil material 100m³ Supply and installation of ground anchors, not exceeding 5m 440m Supply and installation of ground anchors, exceeding 5m but not exceeding 10m 390m Establish ground anchors by grouting 915m Fabric reinforcement to BS 4483:2005 and BS 8666:2005 reference B1131 110m² In situ C32/40 sprayed concrete for reinforced concrete facing 25m³