Potentially toxic waste seeped into groundwater, Cadia admits

The revelation was confirmed in the recently released Cadia Annual Review for 2022/23.

The document stated that "increases in arsenic concentrations and a decrease in the sulfate-chloride mass ratio, were observed in (Ordovician bores, MB94 and MB95), which further supports localised interaction between the tailings decant water and groundwater."

Groundwater is the water below the land surface while tailings are the waste materials left after the target mineral is extracted from ore and can include heavy metals such as copper and lead, copper.

Both of the bores where the observation was made have now been decommissioned.

However, Cadia claimed the seepage was nothing to worry about.

"We acknowledge concerns raised by the community and we can confirm that, based on independent expert advice, there is no impact on offsite groundwater or surface water from Cadia's operations," a Newmont spokesperson said.

"Cadia's Tailings Storage Facilities (TSF) are designed and operated in line with Australia Standards and our operating approval."

The spokesperson added that the groundwater monitoring network features more than 100 monitoring bores, both on site and across the Cadia district.

"This network has been installed to assist in the early detection of any potential changes to groundwater levels or quality, with particular focus on shallow groundwater interactions with local water sources.

"All data is openly and transparently shared with relevant government agencies, and the community via the Newmont Cadia website.

"We take our environmental stewardship obligations seriously and reaffirm to our farming neighbours that there are no groundwater impacts outside of our operation."

The report added that the risk of impacted groundwater making its way away from the pit is "minimal".

In wake of the news, Greens MP and water and mining spokesperson Cate Faehrmann said that Newmont's Cadia Gold Mine should be stripped of its Environment Protection Licence.

"It shouldn't take the community trawling through hundreds of pages of reports to find out whether this massive gold mine is safe to live next to, but that's what it's taken," Ms Faehrmann said.

"The upcoming review of Cadia's Environment Protection Licence needs to be strengthened considerably, including by ensuring that limits are placed on the pollutants for groundwater."