The maintenance campaign, which began on 8 March 2017, is scheduled for completion by the end April 2017. The main objective of the dredging campaign is to ensure the Port of Cape Town provides safe navigational channels and berthing facilities for shipping by restoring the original design depths.
Two dredging vessels, the Isandlwana, a Trailing Suction Hopper Dredger and the Italeni Grab Hopper Dredger have been mobilised by TNPA Dredging Services for this purpose. Multi-beam bathymetric surveys are conducted at regular intervals throughout the campaign that will ensure all areas within Duncan Dock are restored to their original design depths.
Dredging is specialised underwater excavation that helps to keep ports and harbours safe and navigable and is a critical aspect of port maintenance.
The Isandlwana, which has a 4200m³ hopper capacity, will remove approximately 70,000m³ of material from the seabed before the end of April. Spoil is pumped into the hopper and can be offloaded by discharging through 10 conical bottom valves.
Pumping ashore is also possible by means of either a floating pipeline, a side discharge mechanism or by ‘rainbowing’, where the dredging vessel discharges material that has been claimed from the ocean floor in a high arc to build a land mass elsewhere, such as during nourishment of beaches, to prevent erosion along the coasts or to reclaim land.
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