NSW’s Cadia goldmine confirms groundwater affected by potentially toxic mining waste
A goldmining operation in the New South Wales’s central west has confirmed groundwater has been affected by potentially toxic mining waste.
The most recent Cadia Valley Operations annual review described an increase in arsenic concentrations in two decommissioned monitoring bores in the mining pit at Cadia Hill, attributed to tailings deposition, or discharge at the mine site. Indicators of seepage at the tailings storage facility were also detected.
The report said findings “further support localised interaction between the tailings decant water and groundwater” at the pit but the “risk of this groundwater migrating away from the [mining] pit is minimal”.
Tailings are the waste product of the mining process and can include heavy metals such as lead, copper and arsenic. The waste is processed either into a paste, dehydrated and dry stacked, mixed with cement and stored underground, or mixed with water to create a slurry, held in a tailings dam or pond.
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Monitoring bores located at the tailings storage facility also showed “some indicators of seepage affecting groundwater chemistry”, the report said, but with potentially affected groundwater remaining “of good enough quality that it is unlikely to represent a risk to the surrounding environment”.
A spokesperson for Newmont, which owns the mine, said assessments over two decades had concluded that any potential seepage from tailings facilities was within acceptable criteria, approved by the planning department as part of the mine’s approval and not discharging into local waterways.
“The monitoring and management programs undertaken by Cadia have been developed in conjunction with independent groundwater specialists to ensure we do not have an impact on downstream receptors,” they said. “Any seepage from the tailings storage facilities (TSF) is localised to the immediate TSF area and contained, and does not have an impact on downstream groundwater receptors. This data is reported annually to relevant government agencies and shared with the community.”
After the mine’s operator pleaded guilty to breaching clean air regulations last year, community advocates have expressed concern that contaminated water could enter fault lines on the site, spreading to local waterways.
A spokesperson for the Cadia Community Sustainability Network called for nearby waterways and water supplies to be tested for potentially damaging particles and for regular updates to be provided to the community.
“Claims that contamination is limited to an area close to the tailings dams are not credible; water will flow through aquifers and fault lines,” the spokesperson said. “The mine and in particular the pit being used to store tailings and process water is built on a series of fault lines.”
“All downstream users of the Belubula River and owners of bores in the vicinity should be extremely concerned. The priority now, regardless of what happens to the mine operations, must be to protect the Belubula for all Australians.”
The state Greens MP and the party’s water spokesperson, Cate Faehrmann, said the government had “downplayed the seriousness” of studies undertaken by residents near Cadia. She called for the upcoming review of the mine’s environment protection licence to require limits on pollutants in groundwater.
“This confirms what the community has been sounding the alarm about for years – that the Cadia mine is polluting the air and water with potentially serious ramifications for human health,” she said. “Throughout every step of this process, the government has put taking tough action against Cadia in the too hard basket … Surely, this is enough for them to now act.”
The Environment Protection Authority’s executive director of operations, Jason Gordon, said the agency had “identified groundwater monitoring as a priority for our current review” of the Cadia mine licence.
“As part of our review, we’re also investigating community concerns about groundwater contamination and if any breaches are detected, we will consider taking regulatory action.”
Gordon said the EPA would seek independent advice on groundwater monitoring data and “make any necessary changes to the licence that will ensure the highest operational standards and reduce potential impacts on community and environmental neighbours”.