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I mpact of Current Rainfall / Flooding on Acid Mine Drainage in Gauteng

Presentation to the Portfolio Committee: Water& Environment. I mpact of Current Rainfall / Flooding on Acid Mine Drainage in Gauteng. Presentation by Mr N Nepfumbada Acting Deputy Director-General: Policy & Regulation 26 - 27 January 2011.

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I mpact of Current Rainfall / Flooding on Acid Mine Drainage in Gauteng

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  1. Presentation to the Portfolio Committee: Water& Environment Impact of Current Rainfall / Flooding on Acid Mine Drainage in Gauteng Presentation byMr N NepfumbadaActing Deputy Director-General: Policy & Regulation 26 - 27 January 2011

  2. High rainfall / flooding leads to increased ingress of water into mine workings via: • Surface streams • Shallow groundwater systems • Open pit mining Leads to increased mine water levels and decant of AMD 2

  3. Status of Western Basin (West Rand) • Dry season: zero AMD decant or relatively small volume (2 ML / day) + {12.5 ML / day partially-treated mine water} • Wet season: AMD decant of 15.5 ML / day (Dec 2010) up to 30 ML / day (as at Jan 2011) + {12.5 ML / day partially-treated mine water} • Impacts on Tweelopies Spruit flowing to the Crocodile River system. Recent fish kills not due to AMD. 3

  4. Status of Central Basin (Central Jhb) • Dry season: mine water rises by 0.3 m / day • Wet season: mine water rises by 0.9 m / day • Current rate of rise is 0.37 – 0.47 m / day • Despite high rainfall, the rate of rise is less pronounced due to delayed ingress or greater void volume at 500 m below surface level (lateral spreading of water) 4

  5. Status of Eastern Basin (East Rand) • Recent rainfall has increased rate of mine water rise to 0.4 m / day (7 x increase) • Pump station can flood within 16 days at this rate • Grootvlei Mine has reported urgent measures underway to increase pumping capacity 5

  6. Recommendations • As per Expert Team report to the Inter-Ministerial Committee on Acid Mine Drainage, interventions include: • Western Basin: reduce ingress by pit filling and canalising watercourses • Central Basin: ingress reduction by canalising streams over mining areas + grouting (sealing) of mine paths • Eastern Basin: immediately expand culvert in Blesbok Spruit to reduce water entering mine • The above recommendations have been included in a Cabinet Memorandum which will be processed shortly 6

  7. The End Thank you

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