It was foreseen that there would be challenges with the current short term treatment of AMD within the Western, Eastern and Central Basins. The Department of Environmental Affairs granted exemption for the construction and operation of the High Density Sludge Plants in the Western, Eastern and Central Basins and the discharge of neutralised AMD (in terms of the Short Term Treatment of AMD) since it was considered an emergency. Since there was no Environmental Impact Assessment (EIA) conducted and no public participation the possible risks were not adequately assessed.
In order to prevent decant from these three basins, water levels need to be kept below an Environmental Critical Level (ECL). The ECL for the Central Basin was established at 1 467 meters above mean sea level (mamsl). (Please see attached Report.) Due to the high rainfall and scaling of the motors in the Central Basin (and less pumping) the water level is currently about 3.5 m below the cap at South East Vertical Shaft in the Central and is rising at 10 – 15 cm per day.
Approximately 80 million litres were required to be pumped per day from the Central Basin to maintain the ECL.
The subjoined graph shows the volumes which were pumped from the Central Basin from July to August 2022, which were less than the required 80 million litres per day.
Because of the scaling of the motors of the AMD Treatment Plants, the ECL was breached within all three basins. Lower volumes were pumped from the Eastern and Central Basins as a result of the scaling of the motors and problems with the German manufactured pumps, and pumping stopped altogether for some months in the Eastern Basin. 110 million litres per day were required to be pumped from the Eastern Basin. Please see the subjoined graph which shows that 0 litres were pumped from the Eastern Basin during October and November 2022. In December 2022 the water level at the Eastern Basin plant was 35.9 meters below surface.
In the Western Basin, raw AMD started to decant again from December 2022 from 18 Winze into the Tweelopiespruit.
TCTA press statement available below.