Civil Engineering July 2021 | Vol 29 No 6

38 July 2021 Civil Engineering fine sediment. A scour valve to the lower gallery allows the reservoir to be flushed out periodically, when demand is being supplied from the Mhlabatshane Dam. THE FISHWAY A fishway has been incorporated into the design between the second bridge pier and the weir so that the downstream inlet is in the deep channel of the river. The design is novel in that it provides passage for eels and fish found in the river. DIGITAL design In the digital twin of the project, the drawings, specifications and quantities are driven by a detailed virtual model based on collaboration between Umgeni Water and the disciplines covering water, structures, transport, mechanical, electrical, instrumentation, operation and maintenance, and SHEQ. Many design questions needed to be answered and flaws and potential risks identified as early as possible in the design process. From the beginning, conceptual thinking and digital modelling has enabled the design team to address the challenges with practical solutions. The design could be presented visually to everyone as it evolved, thus speeding up the adoption of ideas and the production of detailed designs. Digital design applications are used to detect clashes, prepare accurate drawings, capture quantities, and plan construction sequencing. Digital design can reduce the number of queries from contractors during construction as well as potential claims, delays, and associated unwanted costs. Tender documents can include basic graphic models to help contractors understand the scope of work and therefore price the work more accurately. Viewing software is free online and it is possible to take measurements from a digital model. Regular updates to the model through the construction period will capture the completed works as an accurate “as-built” digital model – a digital twin – of the actual built asset. For the Mhlabatshane Bulk Water Supply Phase 2 project, the digital design approach enables the evolving design concepts to be displayed visually in a detailed and explorable virtual environ- ment, making it easy to see what the final product will look like and helping to reach consensus on design issues.  High lift pump station No.1 is contained in a pump room at the “back” of the structure