Client:Dublin Port Company
DBFL undertook the role of Technical Advisor on this prestigious marine project in Dublin Port.
The roll-on / roll-off (RoRo) jetty at Cross Berth Quay forms part of the overall Alexandra Basin Regeneration (ABR) Project at Dublin Port, the first Masterplan. The dolphin structure is comprised of nine reinforced concrete dolphins, supported on tubular steel piles. Access walkways, fenders, mooring bollards, quick release hooks, ladders and support infrastructure also form part of the works. DBFL provided technical advisory services to the project team on this part of the overall ABR Project.
This project was shortlisted for ‘Engineering Project of the Year’ at the Engineers Ireland Excellence Awards, 2019.
DBFL were responsible for reviewing the various design packages for the works, and provided a construction monitoring role during the construction and handover phases of the project. Particular challenges included the corrosive marine environment. All of the steel elements had to be suitably protected against corrosion risk. Different protection systems were proposed for different elements, including paint systems and galvanizing. A thorough understanding of these corrosion systems was required to maximise the useful life of the system, and to minimise maintenance operations, in line with the client’s functional requirements. DBFL also carried out off-site workshop inspections, to ensure the coating systems were being applied to a high standard.
The ‘flexible’ nature of the dolphin and pile arrangement, which moves under berthing and mooring loads, necessitated that the walkways were capable of accommodating the range of movement in the dolphin structures. In addition, utilities, including a watermain, run underneath the steel walkways and through the concrete dolphins. In order to ensure the watermain could accommodate the relative movement, a flexible coupling had to be provided at each dolphin. In addition, insulation was provided over the exposed sections of the watermain to minimise the risk of freezing in extreme weather.
As Technical Advisors, DBFL were responsible for reviewing designs from multiple third parties, including geotechnical, structural, M&E, and vessel simulation specialists. Due to the complex loading on the structure, a thorough understanding of the following inputs was required from the DBFL Marine Team: ground conditions, met ocean climate, vessel types and sizes, berthing energies, mooring configurations, future dredge levels, soil-structure interaction, corrosivity (including potential risk of accelerated low water corrosion), etc.
The dolphin piles are proposed to be installed with cathodic protection (CP) in the form of sacrificial anodes. Provision of a CP system allows for a reduction in the sacrificial steel thickness required for the piles, thereby reducing the carbon footprint of the works. DBFL have undertaken detailed reviews of the Ro-Ro Jetty and the surrounding combi-wall berths recently installed as part of the ABR project, and have advised on corrosion monitoring and mitigation measures for these high value assets of national importance.
Bespoke precast units were developed to act as permanent shutters for the nine mooring and breasting dolphins. DBFL reviewed the structural design of these units, and carried out over water inspections during the in-situ concrete infill pours to inspect the reinforcement and to monitor the sequencing of the works (two-part pour required to avoid overloading the precast walls). DBFL also advised on the concrete mixes, which required significant pumping effort, given that the eastern-most dolphin was nearly 300m from the onshore concrete wagons. Innovative Quick Release Moorings (QRMs) and LIDAR technology were also incorporated in the works to aid with berthing and disembarking operations, particularly in poor weather.
Project Director
