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Johannesburg - An ecological disaster is threatening the Witwatersrand if a project to purify acid water discharged from the area's old mines is unnecessarily delayed.
The mining industry - which is under pressure from the Department of Water Affairs to do something about the threat posed by underground acid mine water to the region's water table - has until October 2011 to find a solution.
The mining industry has a unique plan, but is worried that delays can lead to important deadlines not being met, with serious consequences for the environment.
About 155m litres of acid water filters from the mining voids across the Witwatersrand every day, and the level of this toxic water is continuously rising.
"By October 2011 the acid water will reach the natural water table. The later we begin construction of this project after January 2010, the greater the damage will be," said Jaco Schoeman, CEO of Western Utilities Corporation (WUC), the South African subsidiary of the London company WM Global.
The remaining gold companies in the area have appointed WUC to find a feasible and sustainable solution. The company will finish its environmental impact study of the project by the end of October.
It hopes to have approval from all the regulatory authorities concerned by the end of this year, so that in January next year it can begin constructing its water purification plant and pipelines, through which millions of litres of toxic mine void need to be pumped out of the old mine shafts to avert the menace of an environmental disaster.
"If we can begin building in January next year, we'll be able to start work by the second quarter of 2011. It's clear that any delays will have consequences for the environment," Schoeman said.
The pace at which the underground acid water is rising is being regularly monitored. It has been consistently been predicted for the past two years and by this stage predictions are pretty accurate.
"We can perhaps predict that it will reach the natural water table by October 17, but it could arrive on October 25 - but October 2011 is the deadline," said Dirk Kotze, WUC chief financial officer.
Empty tunnels
Where the world's largest, richest gold reef was located 120 years ago there are today literally thousands of underground rock cavities, shafts and empty tunnels.
While mining was in progress, millions of litres of underground water were pumped to the surface to keep the mines dry. But over the past decade, while the gold industry has been dying a slow death, pumping operations have tapered off.
The mine water has gradually begun to push up from the lower earth crust, ever closer to the natural groundwater table, which is about 50m to 100m deep.
A chemical reaction occurs when the water and oxygen come into contact with the underground sulphur-bearing pyrite rock, increasing the water's acid content.
Salts are also dissolved in it and, what is worse, the water absorbs heavy metals like iron, manganese, nickel, cobalt and even uranium, and carries these toxic materials upward - to the natural water table.
Fortunate news
The only piece of good fortune is that the underground tunnels and shafts across the Rand are interlinked. The area consists of three geological formations - the West, Central and Far East Rand.
On the West Rand the rising acidic deluge can be arrested by pumping it out through the East Chamdor shaft and from there dumping it in the old DRD No 4 shaft in Roodepoort, which will carry it to the Central Witwatersrand Basin.
The water level in the central portion can again be controlled by pumping it out of ERPM's South West Vertical Shaft, south of Germiston, for storage in ERPM's old storage dams until it can be purified in the special water purification plant designed by the CSIR.
On the Far East Rand the level of the acid water will be controlled by pumping it out of the Grootvlei No 3 shaft, which now belongs to Pamodzi Gold, and sending it direct to the new purification plant.
There the water will be purified to a standard suitable for human consumption.
The plan is to sell it to Rand Water and pump it into the Klipriviersberg reservoir close to the purification works.
But one of the most important requirements before construction can start in January is to conclude a purchase agreement with Rand Water.
"We are still negotiating the price and the required quality of the water to be delivered," said Schoeman.
- Sake24.com
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