Gavin & Doherty Geosolutions – Designs on Dinish Wharf

The Dinish Wharf extension scheme, located on Dinish Island, Castletownbere, County Cork, in the Republic of Ireland, is an ambitious project, which when complete will see a doubling of the Dinish Island facility through the provision of 216 meters of extra landing berth. The project will also provide 0.9 hectares of highly usable reclaimed quay storage area, two new breakwater structures at the entrance to the harbour, the navigation channel dredged to -6.5mCD and a berthing pocket dredged to -8.0mCD, to further facilitate landings by vessels up to100m length overall.

The project, which is co-funded by the Government of Ireland and the European Union, forms part of Ireland’s Operational Programme (OP) and is supported by the European Maritime and Fisheries Fund (EMFF) 2014 – 2020. The Irish OP is aimed at achieving key national development priorities in the agri-food sector, along with “Europe 2020” objectives.

Castletownbere Fishery Harbour Centre is one of the six designated Fishery Harbour Centres, which are owned, managed and maintained by the Department of Agriculture, Food and the Marine. The last major landing quay development in Castletownbere was completed in 2010. Since then, overall landings into Castletownbere have increased by 60% in volume from 19,030t to 30,522t. The value of landing increased from €29.9m to €99.4m in 2017.

Appointed by main contractor Keating Construction Ltd, Gavin and Doherty Geosolutions (GDG) has been working on the delivery of the detailed design for the extension project.

Specifically, works comprise the installation of a 155m long suspended quay wall, supported on tubular piles connected by a suspended deck which is in turn supported on an inner sheet pile retaining wall. The tubular piles for the berthing cope beam are currently being installed from a jack-up barge and the southern section of the wharf comprises of a 45m long berth with three suspended deck spans.
Construction is currently at pile installation stage, but when complete, the layout will be innovative being designed to dissipate wave energy and to minimise wave propagation along the quay wall. The design has included geotechnical interpretation of the soil parameters, development of a construction methodology and sequence and detailed design of all the structural members for the extension. In addition, a suite of 2-D and 3-D finite element analysis were undertaken to optimise the design.

The project involves a significant amount of dredging work in order to increase berthing depths. GDG also advised on an advance sampling strategy for the dredge material to enable testing to run concurrently with dredging operations. GDG’s analysis, which included a sampling program and an assessment of contaminants, has enabled Keating to maximise re-use of dredged material as engineering backfill.

Work on the project began September 2018 and is expected to be complete Summer 2020.