Durban - The Richards Bay Minerals (RBM) mining company is getting ready to bury a 16 million ton radioactive headache in the sand dunes north of Richards Bay.
The company has dug up many million tons of sand from the coastal dunes of Zululand over the past 36 years to extract heavy minerals which are used to make anything from paint to welding rods, toothpaste and aircraft wings.
However, the dunes also contain relatively high levels of naturally occurring radioactive material such as uranium, thorium, radium and polonium.
Although uranium is a natural part of the earth’s crust, it is generally found at very low background levels of around three parts per million (3ppm) in most parts of the world. But around Richards Bay the levels are higher, and once these sands have been processed and concentrated in the mining process, the uranium levels in mining waste dumps can increase by about 50 times to reach levels of more than 150ppm.
And over the decades, RBM has accumulated a 16 million ton pile of discarded heavy mineral sand which contains radioactivity levels considered hazardous enough to be classified and regulated by South Africa’s National Nuclear Regulator.
Known as “tailings”, these heaps of discarded heavy mineral sand have been piled up in a restricted area known as Stockpile H, not far from Lake Nhlabane north of Richards Bay
Stockpile H is fenced off to keep out the public, and RBM is obliged to submit safety reports every three months to the National Nuclear Regulator, which also audits RBM operations.
To protect the public and workers from being exposed to radioactivity, the stockpile has been licensed by the nuclear regulator and covered with a layer of sand about 2m thick. RBM is also required to monitor the nearby area for signs of radioactive water pollution, although these reports are not widely circulated.
Now RBM has applied to the nuclear regulator to bury the stockpile as part of a new project to recycle zircon, monazite and other heavy minerals from the old tailings dumps using newer technology.
According to a draft environmental impact assessment (EIA) published in August, RBM also wants to dump the waste residue in the shallow pits left behind by its current mining operations.
The radioactive residues would be piled up to a depth of about 2m and then covered with a layer of normal dune sand between 50m and 150m thick.
According to the EIA report, part of the rationale for burying the stockpiled tailings is to reduce the potentially “significant impact” of polluting Lake Nhlabane.
But RBM also seems to have financial and other motivations to bury its radioactive legacy.
The environmental report by Golder Associates acknowledges that Stockpile H still releases “small quantities of radiation” and that this situation will continue for several thousand years.
“For this reason… Stockpile H is required to be managed perpetually. This option is not ideal as it would result in the naturally occurring radioactive material being only buried under a thin layer of sand/ tails, plus it also creates a never-ending liability in terms of managing this disposal site and effectively sterilises the land on which Stockpile H is located.”
The report says RBM also looked at the option of “blending” or mixing up the concentrated tailings sand into the original sand from where it had been recovered, but this option had been ruled out because the concentrated radioactive tailings were likely to increase the level of background radiation in dunes rehabilitated after the mining process.
Golder Associates suggests that burying the radioactive stockpile is a more “sustainable option” than leaving it on the surface, and that covering it with a layer of sand at least 50m high would create a natural barrier to reduce the potential risk of radiation exposure to the public and environment.
A specialist report by radioactive waste consultant Dr Japie van Blerk recommends that any RBM staff directly involved in burying the stockpile would have to be formally classified and protected as “radiation workers” and that they should be equipped with protective breathing equipment and wear radiation exposure dosimeters.
However, separate assessments by Van Blerk and other specialist water and geochemistry consultants conclude that the general public would not be exposed in future to significant risks of radioactivity – even if they built houses directly above the new dump sites, planted mealies and other crops or ate chickens and fish potentially contaminated from nearby groundwater and Lake Nhlabane.
Van Blerk’s computer modelling results suggested that if the radioactive tailings were covered by at least 50m of sand then “all potential impacts” from radon and gamma radiation would be eliminated.
His models also simulated radiation exposure to babies and adults exposed over a lifetime to living directly above the buried tailings, swimming in Lake Nhlabane or eating vegetables, fruit, poultry, fish and dairy products exposed to irrigation water in the area.
Because the waste would be buried so deeply, the roots of any crops grown by subsistence farmers were not expected to reach the contaminated waste.
“The highest radiological dose estimated from all of the ingestion and exposure routes combined, is well below the recommended (safety limit) dose constraint of 250 microsieverts a year.”
His analysis did not include the potential risk of future earthquakes or rising sea levels shifting or exposing the buried wastes.
A separate groundwater study also raises question marks about the possibility of radioactive material and other pollution “leaching” into groundwater in certain areas including Lake Nhlabane.
This report recommends that RBM should not dump waste in certain areas as it could lead to “significant levels of localised contaminant concentration that could impact on aquatic environments in specific situations”.
Commenting on the report, the Wildlife and Environment Society of South Africa (Wessa) said it welcomed the investigation into new methods of resolving RBM’s radioactive waste stockpile.
However, the report had failed to describe the full ecological impacts of radioactive pollution on Lake Nhlabane and the Indian Ocean.
Wessa official Carolyn Schwegman said the report suggested that the risk to the aquatic environment was “low” – but the actual effects had not been described in detail. “In our opinion the studies are incomplete,” she said.
Wally Menne, a Durban environmentalist who campaigned strongly against mining at Lake St Lucia, said he did not have the technical expertise to comment on the risks of dumping radioactive waste sands into the dunes.
“But my first reaction is to ask whether this is not simply a matter of dumping the problem in a hole in the cheapest way possible. RBM has made billions of rand of profit over the years from mining the Zululand coast and we need to ask some serious questions about the long-term future of the dune ecology once the company has finished mining.”
Roger Porter, the former head of conservation planning for Ezemvelo KZN Wildlife, acknowledged that there were several places in the world with abnormal levels of natural background radiation.
Nevertheless, Porter said he would prefer to see the waste “blended” and diluted with the original sand rather than buried in a concentrated form.
“A nuclear expert would have to examine all the risks and recommend the best options for disposal, but one has to ask whether this plan is a matter of out of sight out of mind.
“It would also be important to ensure that the project is monitored properly to ensure that the waste doesn’t end up in one big hole.”
According to the UN Scientific Committee on the Effects of Atomic Radiation there are no indications of increased cancer risk in people living in places with higher than normal background levels of radiation.
However, the committee’s website acknowledges that some plants and animals are more vulnerable to radiation than people.
Whereas humans exposed to low doses of radiation showed no direct evidence of health damage, similar low doses were often lethal for birds and animals, frogs, fish and other creatures.
And although the levels of natural background radiation in the RBM mine dumps are high enough to be regulated by the National Nuclear Regulator, there are several places in the world with very high levels of natural radiation.
Examples include the town of Ramsar in Iran, parts of Kerala in India, Yangjiang in China and Areia Preta (Black Beach) in Guarapari, Brazil.
RBM was investigating a number of engineering alternatives and the public would have the chance to comment on the project before the report was finalised. - The Mercury