JOHANNESBURG, GAUTENG — The Johannesburg illegal mining crisis is rapidly accelerating toward a potential century-long infrastructure collapse, according to urgent warnings from leading urban and mining experts. Professor Hennie Grobler from the University of Johannesburg emphasizes that the vast reserves of gold still buried beneath the metro guarantee this structural threat could persist for up to 100 years if left unaddressed.
While the central business district rests securely on a stable granitic dome, the city’s southern periphery is highly vulnerable. David Van Wyk, a mining analyst and researcher at the Bench Marks Foundation, notes that areas south of Main Reef Road—stretching from Springs to Randfontein, including Nasrec, Tokoza, and the FNB Stadium precinct—are in the immediate danger zone. The core of the issue stems from approximately 6,000 abandoned mines that were never legally rehabilitated, repurposed, or re-engineered after large-scale industrial operations ceased.
Van Wyk outlines a dual threat emerging from these neglected sites. First, informal settlements frequently form around old shafts, where residents scavenge scrap metal and venture underground to extract residual gold. This leads to the dangerous practice of “pillar stripping” in bord and pillar mines. Removing the support pillars 500 to 1,000 meters below ground inevitably causes roof cave-ins that ripple upward, destabilizing the surface. Second, the central, western, and eastern mining voids are flooding with acid water. This highly corrosive water dissolves dolomitic rock structures “like chalk,” dramatically accelerating the formation of deadly sinkholes.
The structural integrity of major transport arteries is now in serious question. Van Wyk reveals that during the apartheid era, mine tailing sand was commonly mixed into the concrete and support pillars of major highways, including the M1 and M2. Illegal miners have begun dismantling surface bricks to access the gold-bearing sand within these very pillars. Consequently, the M2 highway faces a genuine risk of collapse. Creating an alternative route is virtually impossible, as the M2 absorbs tens of thousands of vehicles daily from Soweto, the eastern, and western regions. Sinkholes have already appeared on Main Reef Road, and northern Soweto communities are increasingly threatened by both ground instability and toxic acid water fountains, such as those recently surfacing in a primary school’s playground in Davidsonville, near Randfontein.
The individuals driving this illicit activity are not outsiders; they are largely former, retrenched, or retired mine workers who remained in the area after the mines closed. Because they possess intimate knowledge of the underground networks, securing these areas requires leveraging historical data. Van Wyk points out that underground mine plans are readily accessible through the William Cullen Library at Wits University and Mine Managers Association annual conference reports dating from 1909 to the present. He stresses that law enforcement and government agencies are failing to utilize this critical historical intelligence to cut off illegal access.
Compounding the physical danger is a pattern of municipal authorities approving major construction projects without comprehending the historic mine workings below. Van Wyk highlights a massive new “China City” development at the corner of Main Reef Road and Nasrec Road, warning that its weight could trigger a collapse over the underlying void before construction is even complete. Similarly, a proposed housing development (noted in records as 3L2) next to Rivonia, toward the N1 highway, sits on severely undermined land. Future residents there would face extreme risks from structural cracking, sinkholes, and lung cancer caused by radon gas emitted from uranium in the soil.
The absence of proper Environmental Impact Assessments (EIAs) and Environmental Management Plans (EMPs) is often bypassed due to the influence of the “construction mafia,” which secures government contracts without rigorous due diligence. Van Wyk argues that South Africa failed to manage the transition from large-scale mining to small-scale and artisanal mining, and neglected to mandate continuous water pumping or backfilling of abandoned shafts.
To mitigate future disasters, experts recommend that heavily compromised land be denuded and converted into solar farms, rather than bearing the load of heavy infrastructure. Reinforcing existing highways by completely removing mine-waste pillars and replacing them with proper, modern building materials remains an urgent, non-negotiable priority for the city’s long-term survival.
