Central basin pumps set to solve AMD issue

Displaying government’s resolve to mitigate the challenge of acid mine drainage (AMD) in Gauteng’s Witwatersrand, South Africa’s Water and Environmental Affairs Minister Edna Molewa in March attended the lowering of AMD pumps at the Witwatersrand Central basin, which is said to be one of the highest AMD-affected areas in the province.

Located below the greater part of the City of Johannesburg, the Central basin has been the subject of debate regarding the impact of AMD on the future of Johannesburg – both as a city and an economic hub for South Africa.

“It has become critical in our planning that we prioritise this area for stringent attention to ensure timeous decisions and the implementation of emergency measures,” said Molewa.

On March 12, state-of-the-art pumps were lowered into a newly built pumpstation, which conveys AMD from deep in the mine void to the surface, where it will be treated and made safe for the environment.

“This important process will ensure that the AMD does not reach the environmental critical level, which is prescribed by our legislation. The process will also guarantee the safety of the environment and the people,” she added.

The pumps are a short-term solution for the basin, which is now in its final phase of civil works. “The full project involves the establishment of a new AMD pumpstation, an AMD neutralisation facility suitable for high-density sludge AMD treatment and treated water, as well as waste-sludge pipelines,” said Molewa, adding that, when completed, this project should provide a permanent solution for the treatment of AMD in the Central basin.

The installation and construction of the pumps, the treatment plant and the monitoring shafts, which all started in January 2013, is valued at R319-million and is set to be in operation by May.

Addressing those who attended the event, Molewa pointed out that, in 2010, government convened a Cabinet-appointed inter-Ministerial committee (IMC) on AMD. The IMC has since led investigations, which outlined the extent of the AMD situation on the Witwatersrand and the corresponding remedial interventions that are required.

State-owned entity the Trans-Caledon Tunnel Authority (TCTA) was in April 2011 allocated responsibility for the remediation of AMD in the Witwatersrand.

“An appropriate due diligence identified the need for an immediate solution in the Western basin, in Krugersdorp, as well as short-term solutions in the Springs-based Eastern basin and the Central basin, both in Germiston,” said Molewa, who added that these solutions were aimed to mitigate current and near-future AMD risks.

In April 2012, the TCTA implemented the immediate solution required in the Western basin, which resulted in the complete eradication of surface decant of AMD four months later.

“The Western basin was previously characterised by sporadic surface decant, resulting in negative environmental impacts,” said Molewa. She added that the implementation of the immediate solution for the neutralisation of AMD and concomitant surface decant eradication had yielded positive environmental benefits for the area, including improvements in groundwater and surface-water qualities. 

Molewa said she felt confident that the work being done at the Central basin would yield similar results.

“Once these state-of-the-art AMD pumps are in place, an average of 57-million litres a day of AMD will be treated and discharged into the Klipriver,” she said.

The Klipriver is known to be one of the critical tributaries of the Vaal river.

Linked to the pumping process is the treatment of solid sludge. The solid-waste sludge will be pumped into the mine waste storage facilities. “This initiative will ensure that underground AMD in the Central basin is managed at a suitable level to avoid creating adverse environmental and socioeconomic impacts,” Molewa said.

Molewa pointed out that South Africa’s long history of mining on the Witwatersrand is the reason why AMD was a challenge. “As efforts intensify, a proactive approach is needed to prevent similar situations happening in other mining areas, such as in Mpumalanga, KwaZulu-Natal, the Free State and the Northern Cape,” she said.

She added that government planned to continuously apply regulatory mechanisms for the adoption and implementation of long-term AMD and mine- water management by mining companies.

Molewa thanked certain stakeholders for their cooperation and for helping government to achieve its AMD goals, including gold mining companies Durban Roodepoort Deep Gold, Gold 1 International, Central Rand Gold and tailings extractor Mintails.

“These companies have openly granted access to land and mining infrastructure and have also made substantial financial contributions towards the emergency works project,” said Molewa, who concluded that this was a perfect model for public–private partnerships.