Durban - Every year, thousands of holiday makers descend on Durban - not just for its warm weather but for its beaches along the famed Golden Mile.
But little do people know that the sand on the beaches they are standing on in 2019 is not the same sand they stood on last year. This is due to a variety of eco-factors that sees sand that naturally migrates from southern waters becoming trapped on Durban's south beaches. This requires a little help from dredgers to fill the northern beaches.
This is the work of Transnet National Ports Authority’s (TNPA) Dredging Services division which has been hard at work getting the beaches along Durban’s popular Golden Mile ready to welcome thousands of holidaymakers this festive season.
TNPA Dredging Services has a beach nourishment agreement with the eThekwini Municipality.
The port landlord’s trailing suction hopper dredgers (TSHDs), Ilembe and Isandlwana, dredge sand from the sand trap on the southern side of the entrance channel and reclaim this onto the Northern beaches.
Clive Greyling, Civil Technologist in the Port of Durban’s Infrastructure department, explained, “When you go to the beach in December over the holiday period, you’re standing on completely different sand than a year ago. You might recognise the piers, the buildings and the city – but the beach is completely new. That is our role in maintaining the beaches and supporting tourism.”
In collaboration with eThekwini’s coastal engineering, storm water and catchment management department, the port authority plays a crucial role in ensuring beaches are ready for tourists to enjoy, stimulating the economy and boosting Durban as a city.
Greyling said that annually approximately 600,000 cubic metres of sand naturally migrates up the South Coast and gets trapped behind the South Pier in an area called the sand trap.
"With the sand being trapped on the Southern side of the South Pier, the beaches to the north of the entrance channel are slowly depleted of sand. Transnet and TNPA Durban have a corporate social responsibility to collect the sand that has been trapped to put it on the beaches on the Northern side of the channel,” he said.
According to Transnet, the dredging of the sand trap is of paramount importance to the port, keeping the entrance channel and basin open at the correct depth and width, as well as the berths which serve as parking bays for ships inside the port.
A sand bypass scheme had to be constructed in 2009/2010, when Transnet widened the entrance channel. Previously, the municipality owned and operated a similar installation, a sand bypass hopper at Vetch’s Beach.
When the entrance channel was widened to the North by a hundred metres, the demolition involved the removal of the existing sand bypass and Transnet had to replicate the system.
“It’s a very modern, state-of-the-art system that we’ve got going at the moment. The dredger goes out into the sand trap, fills up a dredge load of 3000 cubes of sand in the hopper in under an hour. The dredger comes alongside the bypass station, connects to a floating pipeline and then through a series of pipes and pumps, delivers sand to the sand bypass hopper or directly to the beaches via a direct discharge line,” said Greyling.
The hopper and sand bypass system is designed to seamlessly tie into the municipal sand pumping scheme. The TNPA hopper can take two dredger loads and TNPA is able to pump directly to the beaches or to the hopper from the dredger.
The city manages the outlet points where sand is discharged onto the beaches and where payloaders are used to move the sand on the beach.
TNPA has recently pumped sand onto the new beach area created through the municipality’s promenade extension project from uShaka beach pier southwards towards the harbour entrance.