7.16 Dust management at Vaal River - response to local community concerns
The West Extension Tailings Storage Facility (TSF) was commissioned in 1985 as one of the repositories for tailings from AngloGold Ashanti's Vaal River operations, with approximately 22 million tonnes of tailings having been deposited here to date. The TSF is currently 32 metres in height, and is expected to increase to 60 metres over its remaining lifespan of 12 years. During the dry season (August and September) strong winds can transport fine sandy material from the outer walls and beaches on the side walls of the TSF into the surrounding environment resulting in high dust depositions. This was the subject of community concern and debate in late 2003, and which has been addressed by AngloGold Ashanti in 2004.
A public complaint about TSFs in the area was made in 2002 to the manager of tailings and land at AngloGold Ashanti's Vaal River operations and an article also appeared in the local newspaper the 'Klerksdorp Record.' These complaints were followed by further complaints a year later, specifically about the West Extension TSF, and which were recorded in the Klerksdorp Record on 11 September 2003. The report referred to "serious pollution as a result of fresh winds blowing dust off slimes dams at a number of mines, including AngloGold mines at Vaal Reefs". AngloGold Ashanti responded to the publication and also installed a large water tank to spray down the driving surfaces on the TSF. Despite this, a subsequent article was published on 16 September 2003 stating that "large amounts of dust from mine dumps were blown across residential areas, causing extensive pollution". The company then gave a comprehensive response, which was published in full in the Klerksdorp Record on 23 September 2003, accepting responsibility for the problem and explaining that changes in the method of tailings deposition on the West Extension TSF had led to a temporary major increase in dust levels, but explained that when complete "will make a substantial contribution to dust control". The article also restated the company's commitment to conducting its activities in accordance with the law, and outlined various measures that were already being taken to resolve the problem.
AngloGold Ashanti records all major environmental incidents and institutes immediate remedial action. As a result of this process, in late 2003, a remediation strategy was formulated and implemented in 2004:
- wetting of the bench (an elevated road surface) and side slopes on a daily basis. (The bench materials include a gravel mixture to enhance dust suppression);
- limiting access of vehicles onto the TSF;
- dust suppression trials for a three-month period, by way of immediate and effective, but temporary, measures prior to vegetation. They included a polymer weather cap mix for covering the side walls and a bitumen-based product for bench hardening;
- implementation of a slope irrigation system;
- vegetation of approximately 8 hectares of slopes ;
- upgrading of cyclone system to suppress dust liberation (the using of additional cyclones to deposit tailings keeps the deposition area continuously wet); and
- reclamation of sites that are at high risk to dust liberation.
In addition, in 2004, a dust monitoring programme was established to monitor public exposure to tailings dust. Apart from addressing public concerns, one of the main aims of the project is to measure compliance with future legislation on Air Quality, which will set new dust exposure limits for the public. This data will be submitted to the regulator and summarised annually in a report. AngloGold Ashanti is currently drafting an Air Quality Management Plan to cover all the requirements of the draft legislation, including public reporting.
(See case study: New legislation to impact on air quality management in South
Since implementation, no further complaints have been received from the public regarding dust emissions. This issue will, however, require ongoing vigilance over the operational life of these TSFs.