R1.2bn needed for acid mine water threat

South Africa would need an estimated R1.2bn to clean up acidic water threatening to spill out from abandoned gold mines under Johannesburg and adjacent areas, a report said on Thursday. The dangerous cocktail of chemicals has been building up in mine shafts dug more than a century ago to tap one of the world’s largest gold deposits and stretches scores of kilometres under Johannesburg. “The problems posed by acid mine drainage will have implications far into the future, with impacts likely to continue for many years,” said a report by a team of experts released by the water ministry on Thursday. The report recommends building a series of pumping, treatment and monitoring stations starting immediately with pumps in place under Johannesburg by March 2012, just months before the acid water is expected to reach environmentally critical levels. The costs are estimated at R441.7m for capital expenditure, R121.2m for annual operating cost and R626.3m for long-term costs related to preventing water from flowing into the cavities, the water ministry said. Acid mine water has plagued derelict mines globally for decades but most of the damage has been in remote areas. The problem for Johannesburg is that the city was built over its gold mines and the land that could be affected is occupied by some of the country’s biggest firms and its most densely packed townships and suburbs. The toxic liquid has already been flowing out of mines to the west of the city from what is know as the Western Basin. Acid mine water is now about 500m below the surface in the Central Basin under Johannesburg, rising on average of 59cm a day, and about 700m below the surface in the Eastern Basin, the report said. Water accumulating in shafts and tunnels has been reacting with rocks formed about 2.8 billion years ago and triggering chemical reactions that produced sulphuric acid, heavy metals, toxins and radiation.

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