Acid Mine Drainage Bubbles To Surface
June 18th, 2009South Africa. Every day 300 million litres of water laced with sulphuric acid and heavy metals, known as acid mine drainage (AMD), bubbles to the surface around South Africa’s biggest city, Johannesburg.
In July the government is to introduce a Regional Mine Closure Strategy that will manage mining districts rather than individual mines, said Stephinah Madau, Acting Chief Director of Mineral Policy at the National Department of Mining. South Africa is a treasure trove of minerals – from gold to coal – and close to 150 years of exploitation has driven the country’s development.
Historically, mine management and environmental impact assessments (EIAs) have been done on a mine-by-mine basis, neglecting the multiplier effects that a heavily mined area can have on the environment, said Prof Terrance McCarthy, of the Witwatersrand University’s School of Geosciences. The new framework is an attempt to manage entire mining regions and control ADM pollution at its source.
A much larger, and so far unsolved problem, was presented by mines that had closed, where AMD had seeped into the water table, McCarthy said. Researchers have proposed using either natural or artificial reed-dominated wetlands to filter the water and remove the heavy metals found in most AMD, but McCarthy said it was hard to know which was the best way forward.
”A 2007 report by South Africa’s National Nuclear Regulator identified at least 100 communities in mining areas that were located on radioactive soil due to AMD”
AMD is perhaps one of the most pernicious legacies of South Africa’s long mining history. It occurs when rain or groundwater mixes with the chemical sludge found in mine shafts, becoming contaminated with everything from uranium to sulphuric acid and a host of carcinogenic heavy metals.
According to Dr Koos Pretorius, it takes just 5 to 10 years for the shafts or pits to fill up, eventually decanting like an overflowing bath at the surface and placing land, drinking-water and people at risk.
In places like Middleburg, a farming and industrial town in the northern province of Mpumalanga, AMD has left land unusable and has also filtered into drinking water, some of which carries twice the World Health Organization’s limit on sulphates.
A 2007 report by South Africa’s National Nuclear Regulator identified at least 100 communities in mining areas that were located on radioactive soil due to AMD, 36 of which needed immediate attention.
There are currently 5,000 pending applications for new mine shafts in Mpumalanga alone, many on land identified for redistribution to the rural poor, Pretorius said. If these claims were processed after the mineral rights were granted and AMD had begun to decant, the land would be unfit for agriculture.
Source: IRIN Africa
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