Port of Ngqura (Coega)
The port of Ngqura (Coega), which began commercial ship operations (containers) in October 2009, lies some 20km northeast of Port Elizabeth and is South Africa's 8th and latest commercial port development, situated at the mouth of the Coega River in Nelson Mandela Bay (Algoa Bay). Transnet National Ports Authority of SA is responsible for developing the deepwater port, while Transnet Port Terminals (TPT) has been appointed to handle all terminal operations.
With a water depth of 18 metres, this new deepwater port is very attractive to the new generation units in the oil and gas industry.
An Industrial Development Zone, known as the Coega IDZ, has been developed over the 12,000 hectare site in the area including the river and port, with a 4,500 ha core development immediately identified. The IDZ will serve as a primary location for new industrial development for export driven industries.
The port is of deepwater construction capable of serving post-Panamax dry and liquid bulkers and the new generation of cellular container ships.
The design vessels for the port are:
Dry Bulk Carriers
Deadweight tonnage: 80,000DWT
Length OA: 250m
Loaded draught: 14.0m
Cellular Container Vessels
Deadweight tonnage: 70,000DWT
Length OA: 300m
Loaded draught: 14.0m
The horizontal geometry of the port is such that 150,00DWT bulkers and 6,500TEU cellular container ships can manoeuvre within the port, although initial dredging is being limited to accommodate the design vessels only.
The new port consists of a main eastern breakwater, 2.7 km in length extending into Algoa Bay to a maximum water depth of 18 metres, and a secondary western breakwater 1.125 km in length.
The two breakwaters are positioned and laid out in accordance with the requirement of an exclusion zone of some 500m around the St Croix group of islands offshore from the port.
Five berths (initially) totalling 1,800m of quay wall - two for containers, two for dry bulk and breakbulk cargo and one for liquid bulk cargo have been provided. The berths have 150 tonne bollards and fenders at 20m centres along the berths with a proprietary fender system at the container terminal and double tyre fenders at the bulk berths.
A total of 32 berths have been identified in the fully developed port with the intention of developing the port further up the Coega River valley and southwest along the coast.
The main breakwater is the longest in South Africa. Both breakwaters are of rubble mound construction, with 2,300,000 m3 of armour rock each of 3 to 6 tonnes quarried from the Coega Kop area 9 km inland from the port. A layer of 30-tonne concrete dolosse provides breakwater protection, with 25,000 of these units cast on site and placed in position. Capping of the breakwater took 102,000 m3 of mass concrete, with five caissons anchoring the ends of the breakwaters which required 18,000 m3 of reinforced concrete. The caissons were pre-cast in the dry inner basin ahead of final flooding and floated into position. The caissons are designed in order to be moved when further expansion of the port is required. The quay walls are approximately 6m above mean sea level.
The inner harbour works required 13.8 million cubic metres of material to be excavated. To achieve this an area of 300,000 m2 needed to be dewatered down to 20m below sea level.
Dewatering included the provision of a rock fill wave protection wall on the shoreline and a 1.2 km long bentonite slurry cut-off wall installed down to 20m below sea level.
The five harbour berths were provided by the construction of 1.96 km of mass gravity, voided, concrete quay walls. This work required the provision of some 270,000 m3 of formwork and 6,000 tonnes of reinforcing.
A sand bypass system consisting of jet pumps to divert sand affected by the littoral drift will transfer sand/water slurry from the updrift to the downdrift side of the port (west to east).