ACID MINE DRAINAGE IN SOUTH AFRICA WITH A FOCUS ON MINE WATER MANAGEMENT IN THE WITWATERSRAND GOLD MINING AREADEPARTMENT OF WATER AFFAIRSMBANGI NEPFUMBADAMARIUS KEET
Content of the PresentationAcid Mine Drainage (AMD): The Bigger Picture;Concerns And Risks Associated With AMD;The Witwatersrand AMD Challenge; andThe Way Forward.
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.
Potentially AMD Producing Mines in South AfricaAffected industriesGoldCoalBase metalsAffected areasWitwatersrand and other goldfieldsCoalfields (Mpumalanga, KZN)OKiep Copper District
Existing and New Mining Activities
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); andFlooding and Decanting.
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; andDestroying ecosystems and heritage sites.
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.
Acid Mine Drainage in KZNMajority of mines in KZN are Coal Mines;Most Coal Mines are abandoned and Defunct;Most abandoned mines decanting AMD; andExisting Coal Mines generate AMD but measures are taken to treat AMD.
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.
The Witwatersrand Acid Mine Drainage Challenge
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; andFar Western Basin; Westonarea to Carletonville.
Major Mining Basins in the Witwatersrand
Background (1)Mining started more than 100 years ago;De-watering to explore reserves; No environmental laws;Uncontrolled slime deposits; Uncontrolled releases; andNo in-stream water quality standards.
Background (2)100 Years later;Re-watering;Newly formed voids filling up;AMD formation;Integrity of geology; andDecanting.
East Rand Basin Groundwater Model
Situation in the Eastern BasinGrootvlei 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; andDepartment has taken legal action.
Groundwater Inflow Components
Situation in the Central BasinPumping 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.
Central Basin Water Levels During Pumping
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; andDue to ownerless and derelict mines not all Mines are participating.
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; andChallenges with sludge in Tweelopies Spruit.
LocalitySterkfontien CavesHarmony Mine Decanting
Situation ElsewhereFar Western Basin: mines are operational and no risks yet;
KOSH Basin: Mining companies working together on pumping and a water utility company will be launched to continue with pumping.
Proposed Initiatives: Central BasinFinancial 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; andGovernment still to consider extent to contribution.
Proposed Initiatives: Western BasinDWA 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; andPumps & pipelines for this option: R 40 M.
The Way Forward
States Liabilities at Strategic LevelComplex 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.
AMD: The Role of DMRDMRs 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.
A Proposed Public Private PartnershipA 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; andSuch a model will clarify roles and responsibilities.
DevelopmentsMines 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; andMines requested to submit a new proposal to deal with short medium and long term sustainable solutions.
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; andProposal to establish a Program Steering Committee in DWA.
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 AffairsDept of Mineral ResourcesNational TreasuryDept of Science and TechnologyCouncil of GeosciencesCSIRCities of Johannesburg and Ekurhuleni
Possible StructureEnvironmental Minmac:Coordination of Outcome 10: Environmental Assets & Natural resources Output 3: Sustainable Environmental ManagementInter Departmental Senior Executive Committee on Acid Mine DrainageProject SteeringCommitteeLegal Task TeamNationalCommunicationProgramProject ManagerSpecialist Task TeamImplementationTeamOperationalTeamMonitoringTeamPublic EngagementTeamNational GovernmentTechnical Task TeamSupporting structuresMonitoring structures