Historic toxic aluminium dross waste found at a coal mine near Gore is "low risk", but a possible second site is also being investigated, Southland's regional council says.

Up to two truckloads of buried aluminium dross powder were found discharged at the Goodwin mine after community members relayed concerns, Southland's regional council Environment Southland said.

Stuff has reported the waste was the Tiwai Aluminium smelter at Bluff, and quoted a spokesperson for the smelter, who said said a small amount of dross had been buried at the mine several decades ago during a disposal trial.

"We understand it was done within all applicable regulatory guidelines at the time. We are not aware of any other sites,'' the spokesperson said.

A potential second discharge site was also now under investigation, but the council would not reveal further details.

Material at the first site dated back to 1988, before the Resource Management Act was passed three years later, an investigation and search of records had revealed.

In 2021, the council said about 12,000 tonnes of aluminium refining waste was estimated to be stored in various warehouses around Southland, which would be progressively removed.

Council land sustainability manager Fiona Young said the latest find of contaminated land at Goodwin mine posed little risk.

"Given what we know about the quantity - two truckloads, what we know about the sampling that was done ... that showed considerably low level of contamination. There's very low risk at this stage.

"We tested for nitrogen, we tested for fluoride. On both those occasions both that testing came back with low levels and levels we would expect in the environment anyway, based on land use at the time."

The council said moving or unearthing the soil could pose a higher risk than leaving it undisturbed.

In recent years, there has been increasing friction between Southland residents, industry and authorities after high profile cases involving toxic materials.

Southland residents protest about toxic aluminium dross stored around Invercargill and Mataura. Photo: Facebook / Sort out the Dross group

Residents of Mataura were increasingly angry about 10,000 tonnes of potentially dangerous aluminium refining waste that was stored in the town's old paper mill, next to the Mataura River for seven years, until it was removed in July 2021, after contentious disagreements about who was responsible for it.

And Tiwai Point aluminium smelter has been grappling with a backlog of waste materials at its site beside Foveaux Strait, with the clean-up costs pegged at almost $700m earlier this year.

Reproduced with permission