African Minerals and London Mining both rely on offshore transhipment to load the CAPESIZE vessels exporting their iron ore from Sierra Leone to the customer markets. Optimisation of the transhipment location will shorten the transit time of the HANDYMAX and barge shuttle vessels and will hence increase the throughput capacity of the respective logistic chains.

The Challenge

The new location of the transhipment station is to be situated such that operational improvements outweigh investment costs (dredging, mooring stations, etc.).

Our Solution

Royal HaskoningDHV was requested to investigate the preferred location for the new offshore transfer location and the preferred navigational layout thereto, based on an analysis of the following: 

  • Mooring concepts
  • Dredging requirements
  • Nearshore wave conditions
  • Nearshore flow conditions 
  • Sedimentation rates

GIS, wave, hydrodynamic and morphologic models of the Freetown estuary are set-up to assess the relevant conditions and sedimentation rates to be expected at a large potential new mooring locations and the access channel thereto.
In addition, as input for the project’s ESIA, sediment plume modelling is performed to assess the environmental impact of the disposing the dredged material.

The Outcome

Ultimately, an optimised layout for the new transhipment station and access channel thereto was selected.