JOHANNESBURG, Gauteng — The escalating illegal mining crisis in Johannesburg has pushed the metro’s vital infrastructure to the brink of collapse, with experts warning that the structural integrity of the city is under severe and immediate threat. Because vast amounts of gold still lie beneath the surface, the crisis could persist for up to 100 years, creating a compounding danger for residents, motorists, and urban planners alike.
Professor Hennie Grobler of the University of Johannesburg highlights that the sheer volume of remaining underground gold ensures this battle will be fought for generations. While the central business district of Johannesburg sits safely on a stable granitic dome, the southern suburbs—including areas around the FNB Stadium, Tokoza, and Nazareth—face imminent risks from subterranean destabilization.
According to David Van Wyk, a mining analyst and researcher at the Bench Marks Foundation, the root of the issue lies in the region’s 6,000 abandoned mines—sites that historically should have been rehabilitated, re-engineered, or backfilled. Instead, informal settlements have sprouted along the shafts. Residents often strip surface metal to sell to scrap dealers and venture deep underground to extract leftover gold.
This unregulated extraction frequently involves “pillar stripping” in deep-level bord and pillar mines. By removing the structural pillars that hold up the mine roofs—sometimes 500 to 1,000 meters below ground—illegal miners trigger cave-ins that directly impact the surface.
Compounding the physical collapse is the influx of acid mine drainage. The central, western, and eastern mining voids are rapidly filling with acidic water. This water aggressively eats away at dolomitic rock structures, dissolving them like chalk and dramatically increasing the frequency of dangerous sinkholes.
Highways and Public Spaces at Severe Risk
The threat extends heavily to critical transport networks. During the apartheid era, mine tailing sand was frequently used in the concrete mixes and support pillars for major highways, including the M1 and M2. Today, illegal miners are dismantling surface bricks to access the gold-bearing sand beneath, effectively hollowing out the very pillars that support these busy routes.
“The M2 highway might collapse,” Van Wyk warns, noting the near impossibility of creating an alternative route for the tens of thousands of daily commuters traveling from the east, west, and Soweto. Serious sinkholes have already appeared on Main Reef Road, and residents in southern Soweto face the dual threat of ground collapse and toxic acid fountains. In Davidsonville, near Randfontein, acidic water is already bubbling up into primary school playgrounds.
To save these vital arteries, experts argue that old, mine-waste pillars must be entirely removed and replaced with modern, proper building materials—a massive but necessary engineering undertaking to extend the lifespan of the city’s roads.
Historical Intelligence and Unregulated Development
The illegal miners driving this crisis are often highly skilled, consisting of retrenched or retired mine workers who remained in the area after large-scale industrial operations ceased. They possess intimate knowledge of the “underground city.” Furthermore, historical underground plans are readily accessible in archives, such as the William Cullen Library at Wits University and Mine Managers Association reports dating back to 1909. Despite this, law enforcement and government agencies have largely failed to utilize this intelligence to secure the shafts.
Equally alarming is the trend of municipal authorities approving massive new construction projects over highly compromised, undermined land without conducting adequate Environmental Impact Assessments (EIAs). Van Wyk points to a major new “China City” commercial development at the corner of Main Reef and Nasrec roads, which may be too heavy for the geological voids beneath it and could collapse before it is even fully operational.
Similarly, proposed housing developments near the N1 highway on the western side threaten future residents with severe structural cracking, sinkholes, and lung cancer risks from uranium-induced radon gas. According to Van Wyk, the influence of the local “construction mafia” often allows developers to circumvent crucial land investigations and secure government contracts without proper environmental management plans.
A Call for Transition and Rehabilitation
With large-scale industrial mining in Johannesburg having ended, the region has failed to manage the transition to small-scale and artisanal mining, nor has it made provisions for the continuous water pumping and underground maintenance required to prevent surface disasters.
Looking forward, experts suggest that heavily undermined and compromised land should be denuded and repurposed into solar farms rather than supporting heavy infrastructure. Until the historical subterranean reality of Johannesburg is properly addressed and secured, the city’s surface will remain in a precarious and dangerous state.
