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Winde changes direction on AMD

Written by  Thursday, 07 July 2011 11:16
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"The findings of the recent Winde Report are significantly anomalous to the findings of public domain official reports and peer reviewed academic reports," says Mariette Liefferink, CEO of the Federation for a Sustainable Environment.


The Federation (FSE) is calling for an urgent public review, with public participation, of the findings and recommendation of the latest report on Acid Mine Drainage done by the Mine Water Research Group of the North-West University. The group conducted a desk-top study to assess how far underground infrastructure in the CBD of Johannesburg may be affected by rising mine water levels in the Central Rand, led by Professor Winde.

The Winde Report follows closely on the AMD report to the Inter-Ministerial Committee and Cabinet, concerning the Central Rand.

The Winde Report slams the report to the Cabinet as being "a premature, somewhat hasty response to a largely media and interest group driven campaign that appears to have inflated, misrepresented and exaggerated possible risks associated with the filling of the mine void."
Further, the Winde Report concludes the AMD report to Cabinet, "lacks a thorough analysis of available data and leaves many crucial aspects superficially covered." These issue include the volume of the expected decant, the compilation of sources of the ingressing/decanting water, water quality and relationship to rainfall, the rate of rise of the mine water table and date of decant, "as well as the spectrum of associated risks".

Liefferink says "We are concerned that hundreds of investigations have been conducted and official and peer reviewed academic reports have been published yet there has been no implementation of the recommendations of the investigations. What is urgently called for are not more investigations, but implementation of the findings and recommendations of the reports, which were funded by taxpayers."

According to the Winde report, the main pollution sources of void water are not located underground but on surface, (this could include tailings and other mining residue deposits which cover a large percentage of the surface catchment above the voids). Liefferink calls for more responsible management of tailings dams, mine infrastructure and rock dumps, and enforcement of non-compliance with environmental laws in this regard.

The Winde report states:
"Where the rising mine water will come into contact with the near surface aquifer, U contamination is at least initially to be expected. The associated radon risk needs to be assessed especially for informal settlements where the radioactive gas (formed ongoingly through the radioactive decay of uranium contained in the mine water) can easily accumulate in low-lying poorly ventilated shacks which often lack concrete floors that could limit a radon influx.

Since shafts are directly connected to the mine water and act as preferred conduits for equalizing barometric pressure differences between the void and the surface, it is likely that radon can reach the surface relatively quickly and well before it decays (the half life of Rn is 3.8 days) even in areas where the water table will remain deep below the surface. Thus radon is likely to already escape from the shafts well before the flooding of the mine void is complete. This renders shafts potential hot spots for radon exposure of surrounding areas. With over 100 shafts distributed across the mining belt the potential for radon exposure is considerable. The identification of affected areas may be difficult especially where old shafts have been covered with soil, or other material. As radon is odourless and the covered shafts invisible such spots are particularly dangerous for nearby residents."

The FSE is calling for:

  • An urgent public review, with public participation, of the findings and recommendations of the Winde Report by the Inter-ministerial Committee (IMC) on (Acid Mine Drainage) AMD since the findings are significantly anomalous to the findings of public domain official reports and peer reviewed academic reports.
  • The National Nuclear Regulator (NNR) to take a regulatory decision regarding the findings that residents in one of the most densely populated areas of South Africa may be exposed to the radioactive gas radon via shafts as a result of the flooding of the Central Basin.
  • An investigation into the impacts of mine water rising in the underlying deep void of the Central Rand goldfields upon support infrastructure (e.g. the M1 highway) since old tailings deposits have been incorporated to support infrastructure and possible subsidence can occur due to the liquefaction of unconsolidated fill material.
  • In view of the current flurry of applications for the reclamation of tailings within the Witwatersrand goldfields, an urgent investigation of the possible contribution of tailings reclamation activities on surface to AMD. The associated contribution to ingress is likely to be considerable as old tailings are hydraulically mined using high pressure water cannons. This introduces large volumes of additional water into a highly disturbed area where surface mining and subsequent filling may result in exceptionally high infiltration rates. main pollution sources of void water are perhaps not located underground but on surface. This could include tailings and other mining residue deposits which cover a large percentage of the surface catchment above the void. If correct this has implications for the Central Basin
  • Since it may be that the main pollution sources of void water are not located underground but on surface, (this could include tailings and other mining residue deposits which cover a large percentage of the surface catchment above the voids) it calls for more responsible management of tailings dams, mine infrastructure and rock dumps, and enforcement of non-compliance with environmental laws in this regard.
  • While we concur with the following statement: “In order to pro-actively address the identified risks of flooding-induced subsidence of structures in the low lying outcrop zones and the exposure of residents, especially in informal areas, to radon even before the void is completed flooded it is recommended to urgently conduct in depth investigations to quantify these risks", we express concern that hundreds of investigations have been conducted and official and peer reviewed academic reports have been published yet there has been no implementation of the recommendations of the investigations. What is urgently called for are not more investigations, but implementation of the findings and recommendations of the reports, which were funded by taxpayers.