Ashleigh Contracts secured a major new Breakwater construction project in 2018 as part of the £300m Aberdeen Harbour Expansion Project – currently the largest marine infrastructure project underway in the UK.
Ashleigh were initially subcontracted to Dragados in March 2018 until Dragados left the Project in 2020 and Ashleigh continued their involvement as a specialist marine breakwater contractor working directly as Main Contractors for Aberdeen Harbour Board from July 2020 to January 2021.
Ashleigh’s prior direct involvement with the construction of the North Breakwater and ancillary associated specialist marine works from 2018 to date have comprised:-
- Offloading and stockpiling up to 200,000T of Rock Armour imported from Norway – with the armour ranging in size from 1-3T, 2-5T and 3-6T.
- Placement of 280,000T of Core Material imported from local quarries to for the core profile of the Breakwater from seabed levels varying from -4m CD to -10mCD along the seaward 440m length of the 620m long new Breakwater.
- Placement and construction of 80,000T of permanent 1-3T Armour underlayer to the seaward face of the Breakwater and temporary 1-3T and 2-5T armour to the inshore face of the Breakwater.
- Placement of Bedding and Scour Protection stone by both shore-based and floating marine equipment along the seaward extent of the Breakwater.
- Construction of a double-layer 3-6T Toe Mound on the Bedding Layer to for the foundation for the primary armouring along a 440m length and Roundhead of the Breakwater.
- Placement of 2,400No 8m3 (20T) Accropode Units as the primary Armour for the Breakwater
Following Dragados’ withdrawal from the AHEProject in June 2020, Ashleigh reconstructed a 100m length of temporary inshore breakwater construction previously left incomplete by Dragados. These works comprised:-
- Removal of temporary 20T Accropodes and Rock Armour above and below water, clearance and retrieval of storm slumped core material back to profile and cleared from the seabed to original bedrock.
- Underwater Breaking out approx. 260m3 of bedrock to prepare a series of 6m wide level foundations areas in the rock-head a min. of 400mm below the original rock-head.
- Placement of 54No 44T precast Concrete Blocks in a double-row along the 6m wide seabed preparation areas to from the foundation support for the primary armouring units.
- Placement of circa 350No 8m3 (20T) Accropodes on and including construction of the associated 1-3T Armour underlayer on a reprofiled Core.
Additionally instructed works for Aberdeen Harbour Board included Seabed preparation for 50m long x 12m wide Caissons to for the new South East Pier, infilling of Caissons along the North and East Quays and construction of winter closure temporary protection to elements of the North Breakwater and the East Quay.
In addition to the full use of Prolec PCX 3D GPS machine control on all lead-machines constructing the works, Ashleigh Contracts also deployed Echoscope 3D sonar imagery attached to the CAT345 Long Reach during the underwater placement of the 20T Accropode Units using a specialist 200T specialist heavy-lift excavator, a Hitachi Ex1200XXL. The live sonar imagery from the Echoscope was shared by wireless link between the two machines during the placement of each Accropode below water to achieve the best possible interlock. An in-house developed hydraulic rotating and remote-sling release system was also used on the EX1200XXL in the placement of Accropodes underwater to negate the use of divers.
