Port Facilities Assessment for Offshore Windfarm Construction

A port and infrastructure assessment was required by an offshore wind farm operator to review support facilities for the installation of two new offshore wind farm developments in the Irish Sea, UK.

The assessment was undertaken by Seacroft Marine Consultants in accordance with the project timeline. Five ports and facilities identified from the outset as having potential to support the project works were included in the assessment. Additional ports were also identified which are potentially suitable for the project.

The nominated ports were assessed and compared for project equipment marshalling and for nearby available infrastructure. The ports considered were assessed for the ability to accommodate the foundations (monopile or jacket structure) and the wind turbine generator or subdivided to each of these components separately.

The assessment considered the following aspects:

  1. Experience in former offshore wind related projects of the selected ports, including listing of projects and – briefly – former project specific requirements (e.g., size of component storage area, executed tasks).
  2. Overview of possible lay-down/marshalling areas for the different components in terms of storage area and accessibility (transportation routes to and from quayside), bearing capacity.
  3. Verification of the accessibility for installation vessels, supply vessels and/or feeder barges with regards to:
    1. Quayside lengths and water depth at load-out quay including tidal range, mooring capacities.
    2. Channel routes within the harbours to access the quayside in terms of water depth, tidal restrictions, manoeuvrability, height- and breadth restrictions, etc.
    3. Jacking capabilities for WTG and/or foundation installation vessel(s) in terms of soil properties and quay wall strength.
  4. Load bearing capacities at the quayside including determination of potential and available LoLo heavy-lift areas (e.g., WTG full tower foundation) and RoRo possibilities (e.g., MP).
    1. High-level overview of available port infrastructure to transport, lift and maintain the components between time of delivery by pre-transport barges and being loaded to the installation vessel(s) or feeder barge(s).
  5. Identification if further improvements/upgrades of the ports need to be considered to comply with the storage, pre-assembly requirements and quayside capabilities.

The final assessment report summarised with a listing of key characteristics such as available storage area, access restrictions, quay length, etc. and any other constraints or considerations identified.

Following completion of the initial capability assessment, a cost estimate was developed based on “AACE International Recommended Practice No. 18R-97” cost estimate Classification 4.

Cost estimates were provided in accordance with the following basic cost drivers:

  1. Cost comparison of the different ports regarding required infrastructure upgrades to serve as an offshore construction port.
  2. An assessment of risks and opportunities related to the findings of the initial assessment were provided together with estimated cost expenditures and saving potentials for each of the identified risks and opportunities.