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Monday, August 23, 2010 |
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Rock Cladding of Tailings Dam
:: News
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Source: Mike Smith
Environmental awareness and compliance is a major consideration for many mining clients whose tailings dams are nearing the end of their lifespan. Erosion control measures are being built into the design of tailings facilities, with options including vegetation, geomembrane /soil covers and various rock cladding options, if rock is available in the vicinity of the mine.
Rock cladding has proven to be a successful environmental erosion control method and has yielded good results in numerous large-scale projects undertaken by Stefanutti Stocks Mining Services.
This method sees the cladding applied to the side slopes during the operational life and top surfaces of a tailings dam (at the end of the life of the facility) to provide long-term wind and water (rainfall) erosion control. Rock clad side slopes have achieved a 100% elimination of wind erosion and 90% reduction of water erosion when compared with untreated side slopes.
Typical erosion to untreated side slope of a tailings dam.
"Based on research and our experience working on these projects," says Mike Smith, head of the Mining Services business unit, "there are a few guidelines that are crucial for the rock cladding method to be successful."
A detailed engineering design of each unique facility is completed by Stefanutti Stocks, prior to the execution of these works. Once the design is completed site quality control becomes of utmost importance. This includes rigorous quality control and site supervision measures to ensure beyond any doubt that all aspects of the design and specifications are adhered to.
The feature that produces the most problems is the bench drainage system and we always recommend to our clients that existing bench drainage be removed and replaced with properly designed new decant measures. Upgrading existing drainage features often results in inefficiencies.
The visual impact of rock cladding can be reduced with the installation of vegetation pockets and or a mixture of suitable growing medium with the rock, in an attempt to secure seed generation and vegetation establishment on the rock clad surface. This also makes it a more acceptable long-term closure methodology.
Stefanutti Stocks have completed four large-scale projects of this kind:
• ± 12 ha at the Lindum Reef tailings dam;
• ± 50 ha at the Cooke Plant tailings dam;
• ± 50 ha at the South Deep tailings dam, and
• ± 40 ha at the Luipaardsvlei tailings dam.
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