Communities along the KwaZulu-Natal north coast, from the Mandini municipal area in the north to as far south as Ballito, have been enjoying the benefits of reliable and quality potable water from the Lower Thukela Bulk Water Supply Scheme (LTBWSS).
The scheme is one of the largest bulk water supply projects to be implemented in the province, with major components including a 200 m weir across the Lower Thukela River, an abstraction works, a low lift pump station, a desilting works, and a water treatment works (WTW). In addition, a high lift pump station at the WTW feeds 30 km of bulk supply pipelines and a 30 Ml reservoir.
Zutari was appointed to undertake the feasibility investigation, provide the necessary input to the environmental impact assessment (EIA) and licensing process for the required authorisations, and design the first phase of the scheme’s infrastructure.
A key requirement of the project design was for the water supply scheme to be able to remain operational during major floods and droughts, despite high sediment loads in the river. Engineering ingenuity created a sustainable solution and enhanced functional efficiency by designing the abstraction works to remove a significant amount of silt from the raw water before it reaches the treatment works and then returning it to the river. This reduced the processing load on the works, as well as the environmental impact of disposing of large quantities of silt.
The project was fast-tracked, reflecting the urgent need for additional water supply to the local communities in KwaZulu-Natal, while being agile in accommodating the seasonality of the flow in the river. In particular, this meant that the weir had to be constructed during two low-flow winter periods. The project was successfully commissioned in June 2017 and currently has a supply capacity of 55 Ml/d, which will ultimately be upgraded to 110 Ml/d of potable water supply to the towns north of Durban.
“The long-term operability of the bulk water supply scheme has been ensured through our innovative design approach and engineering ingenuity in analysis, using tools such as physical and numerical hydraulic and sediment modelling,” says Stephan Kleynhans, Technical Director at Zutari.
The long-term operability of the bulk water supply scheme has been ensured through our innovative design approach and engineering ingenuity
*The Aurecon Africa business has been officially renamed Zutari as at 21 July 2020. Zutari acquired Aurecon Middle East on 20 November 2020.