WATER IN MINING AMD is a threat to natural water resources AMD in the Eastern Basin SORTED by September 2015 The threat of acid mine drainage decant from the largest source of gold mining-contaminated water – the Witwatersrand basins –will soon be completely under control. With two plants successfully pumping and treating millions of litres of AMD every day from the Western and Central Basins, it’s full steam ahead in the third phase to build the largest R950 million treatment plant yet – for the Eastern Basin, writes Laura Cornish. N ever before has a water treatment project of such scale (valued at R2.5 billion) been undertaken – to treat millions of litres of hazardous, contaminated water – rising to surface from the underground open voids of century-old defunct gold mines. The very gold mines which over time gave birth to the Johannesburg economy started in 1886. Today, 128 years later, there is nothing left to show for the hundreds of decades of mining activity which brought huge riches to the area – except a legacy of unconscious but irresponsible behaviour (nonetheless) which led to the massive water ‘potential-crisis’. Fortunately, blame has been laid aside in response to the urgent need to prevent contaminating the Vaal River System. South Africa’s Water Affairs Department, through its special liability management vehicle TCTA, will oversee the construction of customised AMD treatment plants to put the problem to bed – in the short-term. And the short-term intervention, to do just that, has been successful thanks to the upgrade of the existing Rand Uranium plant in the Western Basin and construction of a new water treatment plant for the Central Basin. But it doesn’t end there. The Eastern Basin, the largest of the three (by AMD volume) requires its own plant as well to pump and treat water stretching roughly from Nigel in the south and Germiston in the west to Modderfontein in the north and Daggafontein (Springs) in the east. This covers a surface area of 768 km 2 with a volume of approximately 400 million cubic metres (Mm 3 ) up to the environmentally critical level (ECL). The water level is also rising approximately 250 mm/day. “The contract for the construction of the infrastructure for the Eastern Basin – using high density sludge treatment – was awarded in May 2014 and construction commenced on 17 June. It is scheduled for completion in September 2015 with a three month trial operation period ending in December. This means the completed treatment plant will be handed over to the Department of Water and Sanitation for operation and maintenance in December as well, effectively making it a realistic 18 month project,” says TCTA project manager Craig Hasenjager. T FAST FAC The 100 M ca ℓ p /d aci a ty y at the Part of the original Grootvlei plant infrastructure 36 MINING REVIEW AFRICA ISSUE 9 2014 pumping i No. 3 sin Grootvle Eastern Ba Shaft