Civil Engineering January-February 2022 | Vol 30 No 1

38 January/February 2022  Civil Engineering T he duckbill design by consulting engineering and infra- structure advisory firm Zutari significantly increases the discharge capacity of both the dam and spillway to boost dam safety by preventing overtopping while at the same time boosting water supplies. “I am happy to report that the spillway is behaving as ex- pected,” reports Dr Frank Denys, Associate and Expertise Leader: Dams at Zutari. George Municipality reports that while the heavy rainfall and flash floods on 22 November had “understandably overshadowed” the dam’s overflowing on the same day, it remained a celebration of innovative engineering and a significant milestone in the city’s long-term water security. AWARD-WINNING INNOVATION “The design is relatively new in the engineering world, and as far as we know is not being used in this way in South Africa,” says George Municipality’s Civil Engineering Services Acting Director, Lionel Daniels. It was extensively researched by Zutari and tested by the Department of Water and Sanitation’s Hydraulic Laboratory in Pretoria, with its shape designed to slow down water flow using basic physics principles. “The design is brilliant in its simplicity, and it was a real victory to see the dam overflow and the spillway working so effectively,” says Daniels. “The project showcased how relatively small, well-engineered and optimised adjustments can provide a more resilient water supply system without compromising on dam safety. Furthermore, the expansion of existing water supply resources is preferable to the development of new sites, as it limits the environmental impact to an already impacted site. Despite the novel nature of the engineered solution, this unique and innovative project had a low capital cost and also has a small estimated maintenance cost,” adds Denys. The project won an award for technical excellence in the 2020 SAICE Southern Cape Branch Regional Awards. Dam eng i neer i ng Innovative spillway design put to the test A unique spillway project undertaken to raise the Garden Route Dam, the main supply for George in the Western Cape, was finally put to the test towards the end of November when it began spilling following torrential rains in the area.