South Africa’s top miners entrust M&D Group, a leading multi-disciplinary construction company, with their mining and water infrastructure requirements. Among the group’s many mining clients is Gold Fields, one of the world's largest mining companies with eight operating mines in Australia, Peru, Ghana and South Africa, home to South Deep, a world-class mechanised mining operation.
In June 2023, M&D mobilised to South Deep Gold Mine in the Witwatersrand Basin to upgrade the operation’s tailing-storage facilities’ (TSFs) return-water dam (RWD) and cascade dams. This is in addition to providing the necessary stormwater-attenuation capacity to mitigate the risk of water spillage from the “dirty” water dams. The infrastructure that M&D delivers will enable South Deep Gold Mine to manage “dirty” water at its TSFs according to regulations that prevent pollution of water resources and mitigate the impact of mining on the environment.
The project is being managed by seasoned Contracts Director, Martijn Groot, who has successfully completed a number of projects for M&D.
Notably, his entire team, except for one other individual, comprises new M&D employees. This project has, therefore, also been an ideal opportunity to familiarise the new staff with the company’s unique processes, underpinned by important core values that always ensures a successful outcome. These commitments that M&D makes to its clients include:
- To Be Safe
- To Do it Right
- To Find the Best Way
- To Do what we Say
- To Grow Together, or Khula Nathi
“Undergoing a tremendous growth phase, we are bolstering our ranks with highly skilled and experienced construction professionals. As committed members of our team, they will help us to continue achieving our vision of ‘growing a Great company with Great People and Great Partnerships’. With 20% of the project already completed, they have demonstrated that they are more than up to the task at hand. Ahead of mobilising to site, members of my team underwent extensive preparation at head-office to ensure that they were closely aligned to our core values so that we again deliver exceptional service to our clients. They now have the opportunity to live them on this worksite,” Groot says.
The contract harnesses three group core operational disciplines, namely Civil Structures, Pipelines and Structural, Mechanical, Piping and Platework.
These M&D Divisions are being supported on this contract by M&D Plant which brings a large fleet of mainly new construction equipment. This sizeable investment in critical plant by M&D Group helps to keep projects on track by mitigating breakdowns. Certainly, it also demonstrates the group’s commitment to the success of its clients’ capital projects.
Moreover, M&D’s pipe fabrication workshop, which was one of the first to have its processes certified to ISO 3834 quality standards, is manufacturing all piping required for the new pumpstations. This state-of-the-art facility also helps to reduce delays by ensuring the timely delivery of quality pipes and components.
Having made a solid start on the contract, M&D anticipates achieving practical completion by the end of September 2024.
Constructed within the footprint of the upper compartment of the existing RWD of TSF 1 and 2, the new RWD will have a capacity of 150 000m3. It will be lined with a 2mm-thick high-density polyethylene (HDPE) liner. An underdrainage system will be installed below to limit hydrostatic uplift of the liner. It will drain to a single sump, which will be emptied into the RWD by a duty and standby pump. A concrete-filled geocell will be installed above the liner as a ballast to further reduce uplift.
A concrete-lined silt trap will be installed at the inlet of the new lined RWD. The provision of vehicle access will enable silt to be removed from the silt trap mechanically. Meanwhile, a bypass pipe will divert flow around the silt trap during de-silting operations.
The capacity of the upper compartment of the existing RWD of TSF 1 and 2 will also be raised by M&D. This will be achieved by excavating the upper compartment of the RWD basin to a depth of about 3m below the current spillway level. The existing upper compartment drain inlet structure will be removed and the outlet pipe sealed.
Collector drains will be installed to convey water that decants from the TSF solution trenches; penstocks; and the South Shaft stormwater channel to the new lined RWD.
The new pumpstation will transfer water to either the gold plant or the reclamation project, via an existing pipeline. There is also the option to transfer the water to the Doornpoort RWD by using the Doornpoort return-water pipeline in reverse up until the “Y-junction” and then via an existing 450mm-diameter pipeline. Two variable-speed drive centrifugal pumps will be installed inside the pumpstation to efficiently match the inflows to the RWD on demand. Each pump will have the necessary capacity to supply the expected peak demand on their own and, in this way, provide the required redundancy in the system. The delivery pipework will be reconfigured so that one pump can supply the gold plant and the other can transfer excess water to the Doornpoort RWD independently. Featuring electrically actuated
control valves and pumps that automatically prime after shutdown, the system will be fully automated. The pumpstation will feature a reinforced roof and walls to safeguard the mechanical and electrical equipment housed inside against theft.
A pipeline will also be constructed to connect the new pumpstation to the existing pipe infrastructure. This is after the existing DN350 gold plant return-water pipeline is first temporarily and then permanently diverted to the west of the new pumpstation.
M&D’s work scope also entails diverting the existing stormwater channel around the pumpstation.
Moreover, the contract includes de-silting, excavating and constructing a foundation for the existing cascade dams, which collect water draining from the TSF 3 and TSF 4 solution trenches from where an existing pumpstation transfers water to the TSF 1 and 2 RWD system. A 2mm-thick HDPE liner will be installed in both compartments, with an underdrainage system below and a geocell ballast on top that matches that at the new TSF 1 and 2 RWD compartment.
Groot and his team will also demolish the two existing pumpstation suction pipes and inlet structures.
A concrete silt trap similar to the one at the new TSF 1 and 2 RWD will be installed at the inlet to the cascade dams, and it will also feature a mechanical desilting system.
As an example of how Groot and his team are “finding the best way” for Gold Fields, drones fitted with cameras are being used to capture high-resolution aerial images of the construction site. “Our aerial surveys are providing us with an accurate and comprehensive overview of project progress. In this way, we can make more informed decisions and adjustments to the programme that will improve our overall efficiency and quality of workmanship. As opposed to using a third party, we have our own drones and pilots, who also have an intricate understanding of our projects and the expected outcomes. Importantly, they are also closely aligned to our core values,” he says.
At the cutting-edge of technology and innovation, M&D has always been able to easily navigate obstacles, and it continues to develop this capability.
Certainly, this project has also had its fair share of challenges that have required quick solutions. These include large quantities of silt and unsuitable material on site and hard rock inside the basin that need to be removed. Due to the redesign of the RWD wall layout, additional cut-to-spoil is also required, while Groot and his team have encountered extensive hard rock in the areas where subsoil drainage is being installed.
Therefore, the project is an ideal starting point for the company’s new employees, who have already displayed the necessary grit and an ability to think on their feet, two key traits of typical M&D construction leaders.
Rukesh Raghubir, CEO of M&D Group, says that the mining infrastructure market will remain a key growth driver for M&D. “Miners have continued to invest in projects in the country, with capital spending on assets increasing year on year. In 2023, investment in local mining operations increased to 37% from 18% the previous year. This trend bodes well for the group, which has earned a solid reputation for the very high quality of its civil, mechanical and pipeline infrastructure,” Raghubir concludes.