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

2. Leads to increased mine water levels and decant of AMD
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