As gaping sinkholes tear through parts of Mogale City, residents lives hang in the balance. Major provincial routes, the Hekpoort R563 and Zwartkops R374, are crumbling beneath them, turning daily commutes into a deadly gamble.
The Star met with a Geologist Chulumanco Koti who explained that the area along the western edge of Gauteng Province, including Hekpoort, sits on rock formations belonging to the Transvaal Supergroup, specifically the Malmani Subgroup of the Chuniespoort Group.
These formations feature alternating layers of chert and dolomite, a calcium carbonate rock that is prone to dissolution when exposed to rainwater. This chemical reaction weakens the rock, making the ground susceptible to sinkholes and subsidence. The area’s history of underground mining further increases the risk of sinkholes.
Koti described sinkholes as the “sudden or catastrophic collapse of the Earth’s surface, often leaving a circular hole in the ground.” She added that they are broadly classified into karst-related and anthropogenic sinkholes.
“Karst sinkholes form when the underlying carbonate rock dissolves over time, creating voids beneath the surface. The overlying material gradually settles, and sometimes this settling happens instantly, forming a sudden hole. Rainwater seeping through cracks accelerates this process,” Koti explained.
She further noted that anthropogenic sinkholes result from human activities such as mining and groundwater withdrawal. “Historically, the West Rand has experienced sinkholes caused by groundwater dewatering to support the gold mining industry,” she said.
Koti added that the sinkholes pose serious risks to infrastructure and urban communities. But technologies like InSAR (Interferometric Synthetic Aperture Radar) and Ground Penetrating Radar (GPR) can help map and understand subsurface conditions, while maintaining a sinkhole database aids town planners in managing land use safely. Rehabilitation methods, governed by SANS 2001-BE3, consider factors such as post-rehabilitation land use, funding, sinkhole extent, equipment accessibility, and impact on existing infrastructure.
“The aim is to prevent further subsurface deterioration by backfilling and compacting the sinkhole, sometimes using grout mixtures,” she explained.
Given the high risk of sinkholes in this area, the Democratic Alliance (DA) conducted an oversight inspection at the R563 road, where a sinkhole first appearing in February 2025 has since widened from the edge of the road to nearly its centre. Residents also report frequent tyre damage and the absence of street lighting, which they say has contributed to accidents
“Compounding these challenges, the road is on unstable dolomitic ground prone to sinkholes, with an underlying cave system increasing the risk of collapse.”
According to Evert Du Plessis, DA Gauteng Shadow MEC for Roads and Logistics, the inspection revealed that the R563 road is still in use, aggravating its deterioration. “Furthermore, no rehabilitation work is being done on this road,” he said.
Du Plessis claims this directly contradicts the Gauteng Department of Roads and Transport’s official notice that the route had been closed since 10 October 2025 and that “appointed service providers have been making steady progress.”
He added that the team also inspected the R374 road near Cradle Valley Hotel and between Kloofzicht and Glenburn Lodge in Zwartkops, where a sinkhole has remained unrepaired since it first appeared in March 2025.
“This busy road sees around 6,000 cars each weekend, along with numerous cyclists, as people make their way to holiday spots in and around Maropeng, Cradle of Humankind. It’s littered with potholes and has become a site for many accidents,” Du Plessis said.
He added that the DA will be submitting further questions to demand clear explanations for why the R563 road repairs missed their deadline and why rehabilitation continues to fail, despite the department receiving an additional R314.9 million adjustment budget. The party will also insist on a firm timeline for the repair of the Zwartkops R374 road
The Star
masabata.mkwananzi@inl.co.za