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 and a trial project was conducted in October 2017.
The initiative 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 using an undersea pipeline.
Subtech and Katlantic – private contractors appointed by the municipality – are responsible for managing the positioning of the pipeline, as well as the shore side management of the sand, under the guidance of an expert from the Netherlands company which built the Ilembe vessel, Royal IHC.
Portions of North Beach, Dairy Beach, Country Club and Battery Beach were closed to the public from April 20 to allow for month-long pumping operations to take place.
As at mid-May, a total of 194 000 m3 of sand was dredged across the initial beaches – and locals have already noticed the difference.
North Beach has been completed, with about 74 000 m3 of sand replenished in this area.
Work at Dairy Beach started on May 10 and was expected to be completed by May 17. The contractors will be moving to the Suncoast area next.
TNPA Dredging Services executive manager Carl Gabriel noted that Durban and Richards Bay are the only cities in which TNPA has an agreement with the municipalities to replenish sand onto the beaches.
“Our beach nourishment agreement with the eThekwini municipality requires us to provide a minimum of 250 000 m3/y to reinstate the city’s beaches situated north of the channel mouth, owing to the natural migration of sand along the coast.”
He added that a maximum of 500 000 m3 can be supplied, subject to the availability of the upper limit from the sand trap.
“This current project is of high importance to us as it proves that the dredger is able to nourish the beaches from the seaside. This opens the possibility of providing the same service to nourish beaches even further North such as Umhlanga and Umdloti.
“These projects would provide an excellent means of TNPA Dredging Services utilising our spare trailing suction hopper dredger capacity for the benefit of our port cities,” Gabriel commented.
While TNPA has exceeded 500 000 m3/y over the last ten years, climate change and delays in commissioning TNPA’s sand hopper station have necessitated this extra project.
TNPA’s Dredging Services division continues to collaborate closely with the municipality under the guidance of eThekwini municipality coastal engineering, storm water and catchment management manager Godfrey Vella.
TNPA’s temporary solution for sand pumping also includes a direct discharge line 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.