Scottish Trunk Road Network - North West Unit - A82 Glen Gloy Retaining Wall

Tender description

Outline: The existing drystone retaining wall which supports the A82 from the east side, has collapsed in several locations, for approximately 75m in length. The scheme involves the removal of the existing wall and construction of up to approximately 50m in length of reinforced embankment with a shotcrete facing. The wall will be reinforced by passive ground anchors (Estimated 112 No). The proposed sprayed concrete facing will be reinforced with steel mesh to distribute the loading onto the ground anchors. The ground anchors and headplates will be high yield steel. The bolts and headplates will be encapsulated within the reinforced concrete facing Wall Details: The maximum height of the structure is anticipated to be approximately 3.6m. The proposed anchor layout is 1.5m centre to centre (c/c) horizontal spacing and a 1m c/c vertical spacing. The anchors would be arranged in an offset grid layout. Weep holes will be installed through the sprayed concrete facing. Other Works: 187m of drainage, above the failed wall will require to be replaced/renewed. 30m of VRS will require to be replaced, and the verge reinstated. Environmental: The River Gloy lies within 50m of the A82 carriageway and work site. The site lies on the boundary with an Ancient Woodland area as defined by Scottish Natural Heritage (SNH). A Site Environmental Management Plan (SEMP) will be completed with measures to be adhered to during construction. Measures will be utilised during construction to minimise disturbance to species, such as controls on working times, types of machinery and limitation of vibrations.