Civil Engineering August 2021 | Vol 29 No 7

mi n i ng T ailings dams and waste rock dumps – as well as slag dumps at smelting operations – are among the main mine residue deposits (MRDs) that must comply with regulatory requirements GN R704 of the National Water Act. A key aspect of this regulation is that water con- taminated by, flowing from, or following through the MRD must be effectively separated from the clean water upstream of the MRDs. To achieve this, the engineering de- sign needs to include adequate drainage and storage infrastructure, which is appropriately sized for the flows that are anticipated. In the past, an accurate prediction of flow levels could be calcu- lated from the planned site conditions, combined with the historical rainfall data for that region. The sizes required for the water channels and pollution control dams are modelled, providing the basis for design parameters such as widths, depths and lining. VARIABLE RAINFALL EVENTS Changes to climatic conditions are leading to greater variability of rainfall patterns. In many areas, storm events are becoming more intense, while the duration and frequency of these events is also changing. This in turn is making Changes in managing mine‑impacted water at waste facilities Tiaan Bauman Partner and Principal Civil Engineer SRK Consulting tbauman@srk.co.za The task of civil engineers in ensuring the careful management of mine-impacted water around mine waste facilities is being made more challenging by changing rainfall patterns. Civil Engineering  August 2021 31 An existing silt trap due for an upgrade