AN innovative sand pumping initiative between eThekwini Municipality and Transnet National Ports Authority (TNPA) has successfully reinstated sand along eroded sections of Durban’s popular Golden Mile and could offer similar benefits for beaches extending further northwards.
The municipality and TNPA proposed the initiative late last year to tackle beach erosion exacerbated by climate change and inclement weather. A trial of the project was conducted in October 2017.
Carl Gabriel, Executive Manager for Dredging Services at TNPA, said: “Durban and Richards Bay are the only cities in which TNPA has an agreement with the municipalities to replenish sand onto the beaches. Our top priority as the port authority is to ensure that the entrance channels, basins and berths at our commercial ports are safe for navigation. This is achieved through regular maintenance dredging in which our dredging fleet is shared across our ports according to a national dredger deployment plan that ensures our equipment does not sit idle.”
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The special beach nourishment programme involves deploying one of TNPA’s dredging vessels, the Ilembe, out at sea. Sand collected by the dredger during TNPA’s usual harbour dredging operations from the ‘sand trap’ (an area just around the outside of the southern breakwater) is then discharged directly onto the beach via a floating under-sea pipeline.
Private contractors appointed by the Municipality, Subtech and Katlantic, are responsible for managing the positioning of the pipeline as well as the shore side managing of the sand, under the guidance of an expert from Royal IHC, the Netherlands company which built the Ilembe vessel.
This method of sand replenishment – in use globally but not to date on South African beaches – has provided direct nourishment to affected areas of the Durban beachfront in a fast, productive and cost-effective manner.
“Our beach nourishment agreement with the eThekwini Municipality requires us to provide a minimum of 250 000 cubic metres of sand a year to reinstate the city’s beaches situated north of the channel mouth, due to the natural migration of sand along the coast. A maximum of 500 000 cubic metres can be supplied, subject to the availability of the upper limit from the sand trap, a deep hole in the sea on the south side of the South Pier that is used to trap sand that naturally moves northwards due to winds and currents,” said Gabriel.
TNPA’s temporary solution for sand pumping also includes a direct discharge line (DDL) to replenish large volumes of sand from the channel back onto the Durban beaches as quickly as possible.
However, the permanent solution will be the commissioning of the TNPA sand hopper station by the end of May, once final performance testing has been completed at the facility.
The new sand hopper will deliver sand directly into the municipality’s sand pumping booster station for sand to be distributed to the beaches north of the port’s entrance channel. The TNPA sand hopper was built to replace the municipal sand hopper which had to be demolished to accommodate the harbour entrance widening project in 2007.
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