The Port of Ngqura, the first port in the world to have a fixed jet pump sand bypass system, is meeting its rigorous dredging targets of 240,000 metric tons of sand a year, port officials said on Monday.
The computer-controlled sand bypass system consists of jet pumps which mimic the natural longshore drift – the transportation of sand along the coast parallel to the shoreline.
The annual net longshore transport rate within the Port of Ngqura varies from 240,000 to 320,000 metric tons a year.
Not achieving a minimum volume of 240,000 metric tons a year could result in a fine for the port of about R10m.
Ngqura environmental manager Mandilakhe Mdodana said this was an achievement because the port was complying with the record of decision (environmental legislation), which stipulates the strict conditions to be adhered to in the development of a port such as Ngqura in an environmentally sensitive area.
“The Port of Ngqura is the only port in South Africa to have a record of decision for its construction and operation.
“This means that it is the only port that was subjected to environmental legislation during its entire development, operation, and will be during its future development,” Mdodana said. In SA, maintenance dredging is required for the movement of ships in ports, because high and low spots are created due to propulsion wash – the ships’ propellers cause sea bed material to move.
Dredging ensures vessels can enter and exit the port safely.
It helps to halt beach erosion and sand build-up.
This assists with navigation, flood control, coastal development, mining and environment management.
Mechanical engineering technician Freddie Melikhaya, who leads the sand bypass team, said: “The system requires a rigid maintenance programme which keeps it going 24 hours a day, seven days a week.
“The port had to develop and refine maintenance, standby and recovery plans in time to counteract the temporary shortfall as part of a continuous improvement process.
“This included making provision for unplanned maintenance, daily planning and scheduling and improving maintenance techniques – all remaining within budget.”
Dredging targets for other ports include, for example, Richards Bay, which must dredge 1.3-million metric tons a year due to its size, Durban at 500,000 metric tons and the Port of Port Elizabeth at 130,000 metric tons.
Transnet National Ports Authority’s dredging services department is implementing an investment programme in excess of R2bn to renew its fleet, which aids in the removal of about four million cubic metres of excess material from the seabed every year at SA ports.