Underground caverns in Gauteng filling up with Acid Mine Drainage, decanting into Orange River

Miningweekly.com: A central basin beneath Johannesburg and Soweto stretching as far as Alberton, and an eastern basin beneath the East Rand as far as Nigel and Springs.

SHOOT: If these underground caverns fill with acid water, you could conceivably see sinkholes swallowing up Johannesburg properties.

clipped from www.miningweekly.com Acid water is also fast filling up two other underground caverns, a central basin beneath Johannesburg and Soweto stretching as far as Alberton, and an eastern basin beneath the East Rand as far as Nigel and Springs. If left unchecked, this water could also decant and contaminate water that ultimately flows into the Orange river. In the past, pumps kept gold mines outside Johannesburg largely free of water because most water was pumped to the surface, partially treated and released into rivers. Now many of the gold mines have closed or can no longer afford to keep pumping, and vast underground areas are filling up.