JSE-listed gold producer DRDGold says it establishes vegetation on a continuous basis on tailings dams in order to prevent wind-blown dust and erosion from rainwater that could result in litigation costs. These vegetation programmes have been in place since the 1970s.
This is a requirement of the old Atmospheric Pollution Prevention Act and now the National Environmental Management Air Quality Act 2004 (Act No 39 of 24), and of the standards for fall-out dust emissions required by the Department of Environmental Affairs and Tourism.
DRDGold environmental manager Louis Kleynhans says that as part of the company’s social responsibility, the establishment of vegetation ensures that there is minimal dust fall-out over residential and business premises.
“The degradation of unvegetated slimes dams contribute to serious wind-blown dust, the forming of erosion gulleys and the silting up of pollution paddocks that could result in surface water contamination,” warns Kleynhans.
The annual cost of the vegetation programme is between R7-million and R8-million.
The vegetation programme involves site-specific soil analysis for fertiliser and lime requirements, identification of hardy plant species, seed selection for long-term sustainability and salt-tolerant plant selection for flat surface rehabilitation.
The vegetation method is still the leaching technique whereby the pyrite is leached out and lime and fertiliser are added to create a sustainable plant growth medium.
Exemption has been applied for cortadeira selloana (pampas grass), now classified a category one invader plant, to remain on the tailings dams for dust control according to the old Chamber of Mines guidelines for vegetation establishment on tailings dams.” The plants are effective for dust control and, should they be removed, it will be very costly to re-establish vegetation in those areas,” explains Kleynhans.
He adds that there is community involvement through employment of the local communities and the establishment of various dust forums where interested and affected parties and government departments are involved.
He cites the high cost of irrigation water for vegetation establishment, steep side slopes and theft of irrigation equipment as some of the challenges to the programme.
DRDGold acknowledges that its mining activities have an impact on the environment and on the communities surrounding its operations. Impacts are managed proactively in terms of management and mitigation measures contained in the Environmental Manage-ment Programmes in place at all of the group’s active operations.
In its 2008 financial results, the company reported that vegetation programmes for dormant tailings dams are in place at all its operations.
“About 25 ha of top vegetation and 2 ha of side slope vegetation were established at Blyvooruitzicht mine.
The side slopes of No 7 slimes dam were grassed and the top ridge ploughed, at a cost of more than R850 000 to reduce the amount of dust being blown off,” the company said.
As No 1 slimes dam is being kept available for backup, the top has not been vegetated. However, it is ridge-ploughed and a water spray system is being installed.
Some 25 ha of vegetation was established on the side slopes of the Crown tailings complex during the year under review. This operation also makes use of irrigation systems on the top of loading faces and reclaimed footprint areas to control dust at the sites that are in the process of being reclaimed.
On reclamation sites, defined access roads are watered by water tankers for dust control.