Considered in the 1960s to be far flung from any meaningful construction activity, even to a point of possible closure in the 1990s due to low sales volumes, today Jukskei quarry finds itself in the middle of a booming urban area and has become one of AfriSam’s busiest aggregate quarries. While rapid urbanisation in the vicinity has changed the fortunes of the quarry, AfriSam has had to deal with new environmental aspects, which have been addressed through an array of initiatives, writes Munesu Shoko.
Mining at Jukskei quarry commenced in the late 50s, with the operation initially called Hippo Quarries. When first established, the quarry was well outside any built up area, but today, due to rapid urbanisation in its vicinity, the operation finds itself at the heart of a thriving urban area anchored by the one of the largest mixed-use property development South Africa has ever seen, Waterfall City – and is worth R16-billion.
In recent years, the area has been a strategic hub for commercial building, along with complementary civil construction activity. To give an idea, just opposite the quarry, the Waterfall mixed development has already attracted some major projects, and one that quickly comes to mind is the R4,1-billion Mall of Africa, the continent’s largest shopping centre to be built in one go.
Waterfall development encompasses 2 200 hectares of land. It’s larger than Sandton and stretches from Woodmead to Kyalami and Vorna Valley, abutted in part by the suburbs of Buccleuch and Sunninghill. The residential area is partially developed and will, on completion, have up to 18 500 units. It is predicted that the development will have an economic impact of about R106-billion on its completion in 2023.
While all the urbanisation has boosted the quarry’s business over the years to become one of the busiest operations among AfriSam’s 17 aggregate quarries, it has also meant that the operation now finds itself bordered by a built up area, with a business park to the north and a Baldwin property to the south. With new neighbours, some of them only 250 m away, management has carefully managed the transition and the environmental aspects that come with the new setting.
Managing the environmental aspects
With the quarry’s close proximity to a built up area, there are various environmental concerns including land disturbance, noise, ground vibrations and emission of dust arising from movement of machinery and blasting activities. When Modern Quarrying visited the quarry at the end of 2019, AfriSam had responded to these possible environmental concerns with a number of initiatives.
To mitigate excessive dust emission, a water spraying system has been installed along the main haul roads on the quarry. “The system ensures that we don’t generate excessive dust when maintaining haul roads or hauling material from one area to the other,” explains Zielas du Preez, regional manager for AfriSam Aggregates. He adds that from an economic point of view, this innovative static water spraying system translates into less diesel burn as it eliminates the need of a water tank moving up and down the haul roads.
Crushing rock is a high dust activity that in the absence of controls would place workers and the close-by communities at risk. Another key intervention in this regard was the installation of de-dusting sprays in the vertical shaft impactor (VSI) crusher. The system minimises dust generated during the crusher’s start-up process. Water is delivered as a fog, mist or fine spray to the crusher chamber during start-up, where it combines with airborne particles created by the VSI, enlarging the particles and causing them to settle.
“A VSI generally generates excessive dust during start-up when it’s still empty. The spraying system, installed in the chamber itself, is active during the first few minutes of start-up, thus mitigating excessive dust emission,” explains Du Preez.
Meanwhile, the monthly dust samples – performed by a third party service provider – measure fall out to ensure that the quarry doesn’t exceed prescribed limits. Seven sample points have been marked out, inside and outside the quarry to measure the amount of dust generated within the quarry and how that dissipates to surrounding areas.
Another key intervention is noise monitoring on site. Du Preez says the annual noise survey measures noise exposure inside and outside the quarry’s boundary to verify any possible changes from time to time. This is performed by an independent third-party. There are six sample points established, both inside and outside the quarry.
“We have a couple of points along the boundaries outside the quarry to measure the levels of noise we are emitting from the operation. We also have a couple of measuring points away from the quarry to see how the noise dissipates. We will add two more points on the northern side of the quarry where the pit is being expanded,” says Du Preez.
Water is another sensitive environmental aspect that has been carefully managed at the quarry. A few years ago, AfriSam invested in a new water reticulation system. In the past, the operation used water pumped from the nearby Jukskei river, and that has since changed. All water used on site is now pumped from the quarry pit and a borehole onsite.
Monthly water samples are conducted, again by a third party service provider. Water quality is checked in the pit itself and the borehole as well. Seven sample points have been established.
Other initiatives
Elsewhere, lighting has been installed inside the quarry for increased visibility and safety of employees during extended working hours at night. The fence around the quarry has also been upgraded to ensure no unauthorised public access to the operation for general safety reasons. This is considering that the operation now finds itself in the middle of an expanding urban area.
With future environmental considerations in mind, AfriSam has stockpiled top soil removed during a hospital project close to the Mall of Africa. This will cater for future environmental rehabilitation needs at the quarry.
Operation in general
Jukskei operates a total of three processing plants: Primary A-Plant and Secondary Plant functioning as one unit, as well as Primary B-Plant operating as a standalone. The A-Plant has a production capacity of 250-350 tonnes per hour, while B-Plant can produce between 140 and 160 tonnes per hour.
The rock geology is granite, out of which several products are produced. These include sub-base material (G1 and G5), as well as -8 mm crusher sand, 9,5 mmm stone, 13,2 mmm stone and 22 mm stone. The A-Plant produces the -8 mm crusher sand, as well as the 9,5 mm and 13,2 mm stone. The B-Plant has the flexibility to produce base course material and the 22 mm stone.
To optimise production, the plants benefitted from an upgrade in recent years. For example, the A-Plant was installed with a complete programmable logic controller (PLC) for process control. Supporting computer interface adjustment of all process parameters, the PLC system also helps to maintain maximum production capacity at all times and also saves invaluable time during troubleshooting. Additionally, the plant was also installed with a new electrical reticulation system which involved the replacement of the old switchgear system with vacuum circuit breakers.
The operation is a member of industry association, Aspasa, which is renowned for best practice among member operations. In its 2019 Aspasa About Face Audit (environmental), Jukskei achieved Five Shields at 93,75%. It’s efforts in health & safety initiatives didn’t go unnoticed, with the operation achieving Five Shields in its ISHE Audit with a 93,97% mark. One of the key safety initiatives on site is the installation of pedestrian walkaways as part of the quarry’s Traffic Management Plan, which seeks to separate pedestrians from trackless mobile machinery operating on site.
