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Rain, runoff and rare metals – the toxic threat to the Dorrigo Plateau

Is this the place for an antimony mine? I guess that depends what an antimony mine is… Karl Vernes

Hands up those who’ve heard of antimony. Now, keep them up if you can name its chemical symbol, list the world’s leading producers, or even name a single commercial product that contains the element.

Most of us struggle to answer any of these questions. But the residents around Dorrigo, a quiet hamlet on the edge of the Great Escarpment in north-eastern New South Wales, are mounting a campaign against a mining company that plans to mine for this precious metal adjacent to Dorrigo’s World Heritage-listed rainforest.

A World Heritage listed rainforest

Approach Dorrigo from the west and you’re greeted by rolling hills of vivid green scattered with patches of remnant rainforest. Black and white dairy cows dot the hills.

As you get nearer the escarpment, the pastures give way to larger areas of rainforest. There are four distinct varieties – warm temperate, cool temperate, sub-tropical and dry rainforest.

These forests are rich in biodiversity and globally important; they are included in the World Heritage listed “Gondwana Rainforest of Australia”.

Beneath the canopy of coachwood, sassafras, prickly ash, giant strangler figs and dozens of other rainforest trees, threatened species abound. There are red-legged pademelons (a type of rainforest wallaby), spotted-tailed quolls, powerful owls, Wompoo fruit doves, and sphagnum frogs, to name a few.

The red-legged pademelon. Peter Jarman

Turn over a log and you might reveal some of Dorrigo’s smaller wildlife treasures, such as the world’s biggest earwig, or Australia’s largest weevil.

Understandably, the residents around Dorrigo are worried that the nearby biological wonder is under threat from a local mining boom.

Why come to Australia for antimony?

China is the leading supplier of antimony. In 2009 it produced about 140,000 tonnes of the stuff, or about 90% of worldwide production. Australia is at the other end of the scale, producing in that same year a mere 1,000 tonnes.

So why is Chinese-owned Anchor Resources looking for antimony on the Dorrigo Plateau? Part of the reason lies in a surge in the value of the metal.

Traditionally, antimony has been used in lead-acid batteries and fire retardants. Recently, it has become increasingly important to the microelectronics industry for use in semiconductors.

And the Chinese government has recently clamped down on antimony mines in China – closing a number of them – because of apparent concerns over safety of mine workers, and threats to the environment.

In 2009, an accident at an antimony mine in Hunan Province left 26 people dead. It led to the closure of all antimony mines owned by Hsikwangshan Twinkling Star Co. Ltd. – the world’s biggest producer of antimony.

This sent the global price of antimony skyrocketing from $4,000 a tonne in 2009 to a record $10,000 a tonne today, and sparked a worldwide hunt for the commodity.

This search led Anchor Resources to begin exploring reserves at an old antimony mine site at Wild Cattle Creek, north of Dorrigo. With test drilling now complete, the company is confident the antimony reserves will yield “positive financial returns”.

Is this the place for a mine?

But things have changed in Wild Cattle Creek. Since the 1970s, when the mine last produced commercial quantities of antimony, and even since 2009 when Anchor Resources began test drilling, much of the forest around the existing mine shaft has come under the umbrella of the National Parks estate. Some of this has now been listed as World Heritage.

Concerns about mining in this area include the increased noise, dust and traffic associated with mining. These are at odds with the scenic beauty of the rainforest and the thriving ecotourism industry that it supports.

Not just quolls might be in danger. Jane Rawson

But the most serious concerns relate to the inescapable geographical realities of where the mine is located.

It sits atop a mountain within a World Heritage listed catchment that receives very high rainfall. The runoff supports rural and urban populations, livestock, crops, nature-based tourism, and the natural environment of the thriving “Banana Coast” region around Coffs Harbour, a mere 20 kilometres from the mine, and directly downstream.

Antimony is toxic, with side-effects not unlike those seen with arsenic poisoning. The byproducts of the antimony mine at Wild Cattle Creek will include (along with antimony) arsenic and mercury.

All this water – and antimony – has to go somewhere

Apart from being an area of great natural beauty and rich biodiversity, the Dorrigo Plateau is also very wet.

Rainforest needs rain, and Dorrigo gets plenty. The town has an average annual rainfall that exceeds two metres, and in 2008 had its wettest year on record, with a whopping 2,650 millimetres.

The Dorrigo plateau is a rainy place. Karl Vernes

All this water has to go somewhere. In the case of Dorrigo, runoff finds its way via myriad creeks and streams (including Wild Cattle Creek) into the Nymboida River, where it’s captured by the Nymboida Weir.

Water from that weir is pumped to the new Shannon Creek Weir, which provides drinking water for the 250,000 people living in the Coffs region from Iluka to Sawtell.

Suspended sediments from the Dorrigo Plateau do wind up in Coffs Harbour’s drinking water, because eroded red soils that sometimes cloud the reservoirs below can be traced directly back up the hill to potato farms on the plateau.

If the mine at Wild Cattle Creek has trouble controlling its toxic wastes, the costs to people and the environment might make the profits from antimony look like a drop in the ocean.

Contaminated water does escape antimony mines in northeastern New South Wales. In August 2011, following heavy rainfall, a sediment erosion control dam at an antimony mine at Hillgrove near Armidale on the New England Tableland overflowed.

It released arsenic, copper and zinc downstream into the Macleay River, adding to previous contaminated outflows from the mine. The NSW government conceded contaminants will be detectable in river sediments for millennia.

In April 2009, a spill from the Hillgrove mine of up to 3000 litres of slimes containing high levels of antimony, arsenic and lead washed into a nearby creek. The mine operator, Straits Gold, was fined $50,000 dollars in the Land and Environment Court of New South Wales for that leak. The long-term environmental costs of leaks like this can only be guessed at.

More recently, a report commissioned by Anchor Resources has shown elevated levels of antimony and arsenic in waterways adjacent to their exploration lease at Wild Cattle Creek. Antimony levels were recorded at 126 times the Australian and New Zealand Environment Conservation Council’s (ANZECC) guidelines for drinking water.

In the song “Blue Sky Mine”, Midnight Oil’s Peter Garrett sang (with some sarcasm): “nothing’s as precious as a hole in the ground”. At Dorrigo, where “blue sky” days are a cherished reprieve between the days of steady rain, the potential environmental damage that “hole in the ground” might cause needs some careful consideration.

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