Sending mines to rehab: good for health, good for the environment

What can you do with a hole in the ground? It’s about more than planting trees. OZinOH/flickr

In late 1986, residents of Diamond St, Kingston, an outer southern suburb of Brisbane, began to notice a black sludge-like substance seeping through the soil and into their gardens.

Within six months, numerous inexplicable health problems had been reported by people in the affected area and the local government began to warn people to avoid coming into contact with the sludge.

Testing confirmed that the soil and groundwater were contaminated with acid, cyanide, heavy metals and other harmful pollutants. Five years and around $8 million later, the Queensland government had acquired a total of 46 affected properties, relocated the owners and cleaned and capped the site. Now, 25 years after the sludge first appeared, the area is still subject to ongoing monitoring.

The Diamond St problem came from a gold mine, Mt Taylor, which operated between 1931 and 1954. When mining operations ceased, the Albert Shire Council approved the use of the pit for disposal of wastes from recycled oil processing.

This practice continued for over a decade until it was redesignated as a general household garbage and industrial waste tip. After the tip closed the land was redeveloped as a residential subdivision and its previous history was forgotten.

Until 1986, that is.

While it may be tempting to believe that in these environmentally enlightened times these practices would not be repeated, such optimistic thinking would be an ill-founded leap of faith.

In 1996, the Woodlawn open-cut base metal mine near Tarago on the New South Wales Southern Tablelands, closed overnight when mining company Denehurst went broke. Multi-national waste management giant, Collex, stepped in and made a deal with the NSW government which enabled it to redevelop the mine as a waste facility and bioreactor.

During 20 years of mining at Woodlawn, 25 million cubic metres of ore and rock were extracted from what is now a gaping void in the landscape which Veolia (formerly Collex) is refilling with close to half a million tonnes of garbage per year.

The waste is not from the local region, but transported daily by train and truck from Sydney – a 500 kilometre round trip. This is what the waste and mining industries call “mine rehabilitation”.

The former tailings dams that surround the Woodlawn void resemble a lunar landscape. The soil is so contaminated with acid and heavy metals that it is incapable of supporting an ecosystem.

Given the level of acid activity and iron oxidation evident, any instability of the structure of the tailings dams would see contamination of an area which includes the Murrumbidgee and Lake George catchments.

While the mine void itself has been lined with concrete, there is still a risk of groundwater contamination from toxic leachate, and in early 2006 a fire spontaneously broke out in the pit that required seven fire units to bring under control and consumed almost a quarter of the surface area of the pit.

The mining industry is a major contributor to the Australian economy.

It is one of the reasons we escaped the 2008 global financial crisis virtually unscathed. According to Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) it represents around 5% of our annual GDP and around 35% of our total exports. Australian governments, at both state and federal level, have a strong vested interest in the continued extraction of mineral resources.

What is not evident, however, is any interest in ensuring that this extraction is carried out with the highest possible consideration for its impact on both the environment and human health.

In the scramble to clear the way for mining and reap its economic benefits, governments are neglecting what should be a relatively simple approach: clear, consistent policy and standards to ensure mining companies are liable for environmental restoration and site rehabilitation.

The application process for mines does require companies to rehabilitate mine sites. But standards and conditions differ from state to state.

In NSW there is no requirement for companies to state how they will rehabilitate mines and no criteria to determine when a site has been successfully rehabilitated.

Mining companies, quick to point to their responsibility to return a profit to shareholders, are even quicker to avoid the costs and time associated with environmental restoration.

A 2001 ABARE report on mine rehabilitation concluded that if environmental standards for rehabilitation were too high, it may discourage mining and have economic implications.

This argument only holds, however, if the standards are not consistent across all states or applied equally to all companies and all sites. And this line of thinking only reinforces the politically expedient and deeply flawed dichotomy of economy versus environment.

Mine rehabilitation must begin before the first load of ore has left the site, with independent pre-approval analyses of soil and vegetation types, surface and groundwater, downstream landuse and biodiversity. The importance of independently carrying out this process cannot be overstated.

An application currently before the NSW government by mining company Cortona to reopen the Dargues Reef gold mine on the NSW Southern Tablelands proposes that the company will carry out monitoring of groundwater and that hydrological assessments cannot be done until after mining starts.

There are at least six species of federally-listed endangered flora and fauna within four kilometres downstream of the site, but the company surveyed only one in its environmental assessment with no mention of the impact of mining on habitat, nor any assurance of how flora and fauna will be protected or the environment rehabilitated.

Cortona has sunk only two test bores downstream from the site, and their claims that there will be no impact on the downstream aquifer are based on upstream bores. Under current government policy, these standards are deemed sufficient for approval.

The environmental impacts of mineral resource extraction are well documented.

We have the knowledge and technology to restore and rehabilitate the environment after mining, as well as minimise the impact during mining.

We are well aware that rehabilitating a mine site is more than just planting trees. Governments must take a leading role through the legislative process.

Taking advantage of the economic benefits of mining comes with a heavy responsibility to ensure environmental and human health into the future.

Diamond St was the warning bell, we’re now well into overtime.

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