SA needs urgent action on acid mine drainage
1 March 2019
South Africa had to implement the Acid Mine Drainage Long-Term Solution (AMD-LTS) as soon as possible to protect its water security, TCTA Project Manager: AMD Craig Hasenjager said at recent South African Institution of Civil Engineering (SAICE) lecture.
The AMD-LTS aims to provide a permanent solution to the impact of AMD.
Mr Hasenjager was a keynote speaker at the annual breakfast of the Water Engineering Division of SAICE. Also in attendance from the TCTA Project Management and Implementation Department (PMID) were Executive Manager: PMID Johann Claassens, Head of Projects Sibalo Dlamini and Project Engineer Segomotso Kelefetswe.
The event was held on Friday 22 February 2019 in the beautiful surroundings of the Blue Valley Golf Estate in Centurion. Other role players in the water industry were invited to share their knowledge and expertise with members of the SAICE Water Engineering Division, particularly on current issues in the sector.
SAICE’s president for 2019, Brian Downie, gave the delegates an insight into his theme for the year, “It’s a new world’’. The topic the organisation had earmarked for this lecture was AMD and aimed to help SAICE members to understand better what the government was thinking and what its plans in the field were. The organisers indicated that much of what they knew about the AMD project came from media reports.
The SAICE Water Engineering Division preferred receiving information about the project from its implementers.
They explained that this was done to ensure that they worked on accurate information as they sought ways through which they could contribute towards solving the AMD problem and help the government.
Mr Hasenjager, in his keynote speech, covered several themes. These include: The History of Mining, What AMD Is it? Where does it occur? Why does it matter? The government’s response to the problem.
He outlined the history of mining from the time gold was discovered in the Witwatersrand in 1886 through to the 1920s when the area produced 50% of the world’s production of the yellow metal. Until the 1980s, South Africa was still the largest gold producer in the entire world.
KNOWLEDGE-SHARING: TCTA Project Manager: AMD Craig Hasenjager delivers a lecture on acid mine drainage long-term solution at Blue Valley Golf Estate in Centurion
However, in the 1990s, gold mining operations in the Witwatersrand started to decline and had ceased by 2010. “The mining on the Witwatersrand has created an underground void of about 1 billion cubic metres,” Mr Hasenjager said.
“Water and air react with exposed sulphide bearing minerals to form AMD and is internationally known as Acid Rock Drainage.
“During the period when the mines were active, they pumped and neutralised water, but it was still very saline. After mining ceased, the pumping stopped, and voids have been steadily filling with water.”
Mr Hasenjager explained that flooding of mining voids posed a threat of seismic activity and might contaminate shallow groundwater resources. If water reached the near-surface environment, it might cause geotechnical impacts.
He further stated that if the AMD decanted to the surface, it would impact on the ecology and impair the fitness-for-use of receiving water resources. Furthermore, it threatened water security in the Vaal River water supply area. Water must, therefore, be pumped out of the mine voids because not doing so would have dire consequences such as sick livestock and contamination of rivers.
Mr Hasenjager added that AMD-LTS would remove the need for dilution releases from the Vaal Dam. The desalinated water would augment the Vaal River System and delay the need for further augmentation until 2030 as per current demand projections.
However, the Department of Water and Sanitation is yet to quantify the actual amount of dilution needed and is currently updating its model. Staff Writer