ACID MINE DRAINAGE IN SOUTH AFRICA WITH A FOCUS ON MINE WATER MANAGEMENT IN THE WITWATERSRAND GOLD MINING AREA

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ACID MINE DRAINAGE IN SOUTH AFRICA WITH A FOCUS
ON MINE WATER MANAGEMENT IN THE WITWATERSRAND
GOLD MINING AREA

• DEPARTMENT OF WATER AFFAIRS
• MBANGI NEPFUMBADA
• MARIUS KEET

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Content of the Presentation

• Acid Mine Drainage (AMD) The Bigger Picture
• Concerns And Risks Associated With AMD
• The Witwatersrand AMD Challenge and
• The Way Forward.

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What is Acid Mine Drainage (AMD)?

• Acid generation is caused by the exposure of
  rock containing certain sulphide minerals, most
  commonly iron pyrite (FeS2), with air and water,
  resulting in the production of highly acidified
  water containing elevated concentrations of
  sulphate and metals.
• AMD is largely associated with gold coal
  mining.

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Potentially AMD Producing Mines in South Africa

• Affected industries
• Gold
• Coal
• Base metals
• Affected areas
• Witwatersrand and other goldfields
• Coalfields (Mpumalanga, KZN)
• OKiep Copper District

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Existing and New Mining Activities
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Concerns and Risks Associated with AMD (1)

• AMD associated with low PH, high sulphate,
  elevated levels of heavy metals, radio activity
  
• Biggest environmental challenge ever
• Negative impacts on quality of water resources
  (Ground and Surface) and
• Flooding and Decanting.

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Concerns and Risks Associated with AMD (2)

• Inter mine migration of mine water is threatening
  operational safety
• Derelict and ownerless mines may become the
  responsibility of the state
• Instability of geology (sinkhole formation)
• Seismic effects and
• Destroying ecosystems and heritage sites.

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AMD and Coal Mining Mpumalanga

• Mpumalanga produces 80 of our coal
• Most abandoned mines decanting AMD
• Capacity to dilute waste discharge is limited
• E.g. in Olifants River salts will have to be
  removed soon and
• Komati and Upper Vaal have many new
  applications for mining.

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Acid Mine Drainage in KZN

• Majority of mines in KZN are Coal Mines
• Most Coal Mines are abandoned and Defunct
• Most abandoned mines decanting AMD and
• Existing Coal Mines generate AMD but measures are
  taken to treat AMD.

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Addressing the AMD Problem with Coal Mines

• Introduce Integrated Water Resources Management
• Involvement of all stakeholders CMAs, WMAs,
  river forums (e.g. Olifants River Forum), mines,
  local authorities and other relevant departments
  
• Stop illegal mining and implement stricter
  control on discharges (exploration already
  stopped on 5 mines)
• 3 Year project to identify pollution sources in
  Olifants Treatment of AMD to potable Standards,
  two plants already built New Optimum and
  Emalahleni AMD treatment plants
• DWA refurbished Brug Spruit water treatment
  works.

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The Witwatersrand Acid Mine Drainage Challenge
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The Witwatersrand AMD Challenge

• Witwatersrand divided into 4 underground Basins
• Eastern Basin Nigel to Germiston
• Central Basin Germiston to Roodepoort (including
  Johannesburg)
• Western Basin Krugersdorp to Randfontein and
• Far Western Basin Westonarea to Carletonville.

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Major Mining Basins in the Witwatersrand
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Background (1)

• Mining started more than 100 years ago
• De-watering to explore reserves
• No environmental laws
• Uncontrolled slime deposits
• Uncontrolled releases and
• No in-stream water quality standards.

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Background (2)

• 100 Years later
• Re-watering
• Newly formed voids filling up
• AMD formation
• Integrity of geology and
• Decanting.

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East Rand Basin Groundwater Model
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Situation in the Eastern Basin

• Grootvlei is the last mine pumping from the
  Basin
• Water level is currently 700 m below the surface
• Financial problems caused failure to meet license
  conditions
• Sub-standard effluent is contaminating a Ramsar-
  Wetland
• Pumping station can be flooded in 30 days if
  stopped
• Decanting then probable in the town of Nigel and
• Department has taken legal action.

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Groundwater Inflow Components
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Situation in the Central Basin

• Pumping had to stop in October 2008 due to safety
  risks
• Water level is now at about 600 m below the
  surface
• Water is expected to raise by 600 to 900 mm per
  day
• Mines would like to secure their reserves at 400
  m below
• The Environmental Critical Level is proposed at
  150 m below
• Groundwater contamination and decanting below
  Johannesburg CBD can have catastrophic
  consequences
• A new pumping station and upgrades to the high
  density sludge treatment works are urgently
  required to stop disaster.

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Central Basin Water Levels During Pumping
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Situation in the Western Basin (1)

• AMD started decanting in 2002
• Department issued directives to the Mines to pump
  and treat
• Mines established section 21 companies to address
  AMD
• Pumping treatment infrastructure exists, though
  mines have limited capacity and
• Due to ownerless and derelict mines not all Mines
  are participating.

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Situation in the Western Basin (2)

• Heavy rains since January 2010 resulted in
  uncontrolled AMD decant
• DWA intervened by allocating R6,9 M over three
  months period
• Lack of treatment capacity compelled in- stream
  treatment as short term intervention and
• Challenges with sludge in Tweelopies Spruit.

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Locality
Sterkfontien Caves
Harmony Mine Decanting
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Situation Elsewhere

• Far Western Basin mines are operational and no
  risks yet
• and
• KOSH Basin Mining companies working together on
  pumping and a water utility company will be
  launched to continue with pumping.

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Proposed Initiatives Central Basin

• Financial support is needed for pumping station
  HDS works
• Directives stipulating pump volumes can be
  considered
• It will take 13 months to establish the pumps at
  400 m below
• Mines are prepared to fund pumping below 400 m
• Estimated costs for pumping station and to
  refurbish the high density sludge treatment works
  are estimated at R180mil and
• Government still to consider extent to
  contribution.

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Proposed Initiatives Western Basin

• DWA considering further intervention (immediate
  and short term)
• Possibility of diverting decant to Central Basin
  or treatment at source
• Centralised pumping and treatment may save costs
  and
• Pumps pipelines for this option R 40 M.

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The Way Forward
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States Liabilities at Strategic Level

• Complex decisions needs to be made, requiring
  much information
• DWA do not have access to all the required
  information
• DWA doing a project with DMR to collate
  information, specifically on the States
  liabilities and
• More information from mines will facilitate the
  alignment between DWA and DMR strategies and best
  practice guidelines.

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AMD The Role of DMR

• DMRs role is defined by the Mining and Petroleum
  Resources Development Act, Act 28 of 2002
• This act also deals with pollution caused by
  mining activities in sections 38 and 43, the
  latter providing for mining closure certificates
  which requires an approved closure plan and an
  environmental risk report, both aimed at ensuring
  that, amongst others, water resources are
  rehabilitated to standards that conforms to the
  concept of sustainable development. There are
  also several regulations setting out the details
  of such a plan.
• Within the mining basins, some of the mines may
  be classified as derelict and ownerless, or in
  terms of section 46 (1) of the MPRD, may become
  the responsibility of the State.

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A Proposed Public Private Partnership

• A DWA proposal to establish a PPP was accepted in
  principle by the GTT
• PPP based on both Government mines contributing
  to the capital costs of infrastructure for
  pumping and treatment
• A new or existing state agency will be required
  
• This approach can also include emerging mines
  and
• Such a model will clarify roles and
  responsibilities.

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Developments

• Mines through the Western Utilities Corporation
  (WUC) made a proposal to the GTT to address AMD
  management
• Proposal not accepted by DWA due to inter alia
  unsolicited bid and financial support required to
  subsidize private company to enable profit
  making and
• Mines requested to submit a new proposal to deal
  with short medium and long term sustainable
  solutions.

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Recent Developments (1)

• 14 July 2010 Mines submitted new proposal to
  deal with AMD
• Due to the looming crisis in the Witwatersrand
  with AMD, decisions on the management of AMD need
  to be made soon
• DWA busy with Position Paper on AMD and
• Proposal to establish a Program Steering
  Committee in DWA.

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Recent Developments (2)

• Joint proposal by DWA DMR on a new
  inter-departmental team of senior executives to
  oversee the whole process
• Proposed members
• Dept of Water and Environmental Affairs
• Dept of Mineral Resources
• National Treasury
• Dept of Science and Technology
• Council of Geosciences
• CSIR
• Cities of Johannesburg and Ekurhuleni

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Possible Structure
Environmental Minmac Coordination of Outcome
10 Environmental Assets Natural resources
Output 3 Sustainable Environmental Management
Inter Departmental Senior Executive Committee
on Acid Mine Drainage
National Government Technical Task Team
Monitoring structures
National Communication Program
Project Steering Committee
Legal Task Team
Supporting structures
Project Manager
Specialist Task Team
Implementation Team
Operational Team
Monitoring Team
Public Engagement Team
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• Thank You