The “Société Industrielle Nationale et Minière (SNIM)” (National Industrial and Mining Company) has completed in 2013 the construction of a new export facility (berth and associated 10,000 tph shiploader), with the capacity to load iron ore carriers up to 250 000 DWT.
The existing channel is designed for vessels up to 170 000 DWT, but with load limitation (maximum draft of 16.15m).
The study aimed at upgrading the existing channel for Capesize vessels up to potentially 250 000 DWT
The new channel will be 25 km long and will require between 15 to 25 million cubic meters to be dredged, including cemented sand layers and potentially sandstone.
The presentation is proposed to focus on the detailed study performed for the new channel on basis of a state-of-the-art approach based on PIANC report No121. This includes:
- Horizontal design through navigation simulation (over 100 runs in real-time on Full bridge Simulator and fast-time).
- Vertical design based on Response Amplitude Operator (RAO) for ship motion assessment.
- Hydrosedimentary impacts assessment and incorporation in design
- Operational criteria derived from the detailed design (tugs, navigation aids), knowing that the Terminal was operated to date without tugs despite the size of the ships.
The challenges faced through the detailed design encompassed:
- An outer channel long of 20 km with various bends and exposed to strong offshore wave climate impacting the navigation transversally and longitudinally.
- An inner channel and turning basin exposed to longitudinal tidal currents (up to 3 knots), where the main interest was the reorganisation of the berthing operations and nautical accesses to cope with tug implementation, on port facilities where it was not used to date.
A transition area in front of Cap Blanc where tidal currents shift from longitudinally to transversally with intensity up to 4 knots with also sudden exposition to outer swell.