A mining report was published in 2017 claiming that there are over 60 000 mine sites in Australia that have been abandoned, with no attempt at rehabilitation. Some of these mines have dated back to the gold rush days. Currently, there are only a handful of mines that have actually shown evidence of complete rehabilitation in Australia post-mining operations. Overall across Australia, there are 17 well-rehabilitated mine sites in Southern Australia, 1 in NSW, 1 in Victoria, 1 in Tasmania, and none in QLD. In 2012, a QLD’s commission of audit found that there are more than 15,000 abandoned mines in the state, which poses a liability threat of over 1 billion dollars. Due to the large landmass of Western Australia, it is still not known how many mines have been abandoned in WA.

In this article, we will focus on a few chosen abandoned mine sites from Australia, to evaluate the extent of the environmental damage they are having on the environment even after mining operation have ceased. The case studies chosen will be juxtaposed to mine sites that have been properly rehabilitated in Australia. It’s fundamental to understand the consequences of our industries mining practices. It’s time to put our ego aside, and directly address the issue at hand. There are solutions, there are options and there are methods of rehabilitation. As will be discussed, it is possible to have a flourishing mining economy, and still protect the environment.

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Case Studies – Poor Quality Mine Rehabilitation Outcomes

Mt Lyell

The Mt Lyell Mine was utilised actively for over a century for gold and copper mining. It was well known throughout the community that the Mt Lyell mine was discharging smelter slag and mill tailings directly into the river system until 1994. As a result, Mt Lyell mine is known to have one of the worst cases of Acid Mine Drainage cases in Australia. The main components of contaminants included copper, aluminium, iron, manganese and zinc. The concoction of these chemicals when exposed to water, oxides and sulphides produce sulphuric acid. Meaning the water system literally contained toxic levels of sulphuric acid, which killed all life in the river system downstream. Only after years of pollution of the local river system, and assistance from the Tasmanian community was their action taken in rehabilitating the mine. However, there are still areas around the Mt Lyell Mine that are believed to be still toxic to life.

Mt Oxide

The mine at Mt Oxide has been abandoned since 1971. The main issue is that heavy metals from the mine are leaching into the surrounding creeks. There have been attempts to stop the contamination, however, the efforts have been deemed as “band-aid solutions”. Within 2 years there were 3 reports that have found evidence of catastrophic contamination levels of the water system, causing the water to turn light blue in colour. The problem is that these creeks run onto private property, potentially contaminating private underground water sources and flora. The worst case of the contamination was reported to occur after heavy rainfall. To this day, there have been little to no improvements. The Mt Oxide copper and cobalt mine were identified as 1 of 10 mines that were the worst contaminators of water supplies in the Gulf of Carpentaria, and Western Queensland.

mine-site-rehabilitation

Progressive Mining Rehabilitation Cases

Huntley and Willowdale

The Huntley and Willowdale mine in WA was opened in1963 and produced over 34 million tonnes of bauxite per year. The grand scale of its operations forced the mine to expand in size and caused a great deal of deforestation across the entire area. However, Alcoa, the owners of the mine, implemented an ambitious effort to restore the area to 100% after its closure. The company reached this target years later. All of the plant species were reintroduced into the area by strategic seeding. This significantly improved the area’s biodiversity and stabilised the area. The effort took numerous years, and investment in the appropriate resources to achieve this goal.

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Ginkgo Mineral Sands

Environmental damage experienced at Gingko was extensive, the worst damage witnessed was the loss of topsoil, which lead to the destruction of local flora. The topsoil was cleared to make way for the original mine site, and it continued to cause damage as the mine expanded. After mining operations ceased in an area of the mine, topsoil was replaced and combined with timber cuttings from trees that were originally cleared. The increase in biomass in the soil allows for microorganisms to flourish, creating a nutrient-rich environment for bacteria and other organisms to further enrich the soil. The state of the soil is significantly important when it comes to the health of local flora. As local vegetation began to regrow, the native fauna returned to the area, once again stabilising the area. However, this did not occur overnight. Such success was brought about consistent observation. The major challenge for this area was the harsh environment, with low rainfall and irregular distribution of trees it was important to reseed in carefully selected areas. The resulting microclimates assisted in the redevelopment of the area’s natural flora.

Woodcutters Mine

A method of rehabilitation that has not been utilised often enough is the collaboration with the lands indigenous population. The Woodcutters lead-zinc mine in the Northern Territory ceased mining operations in 1999, after over a decade and a half of active mining. There were two major components to this rehabilitation process: one was the filling of the open pit, whilst the other included the repopulation of native vegetation. The most appropriate approach, in this case, was the removal of any contaminated soil that could potentially contaminate local streams of water sources. With over 90% of the team being comprised of indigenous people from the Indigenous Consulting Group, they came to the conclusion that the area was turned into a wetland. Over time it has developed into a well-developed wetland that increased biodiversity in the area and stabilised the surrounding soils and river systems.

Concluding Remarks

From all the cases that have been described and evaluated today, we see that the difference is will and effort. It is possible to rehabilitate a mined area. The final article in this series will provide a comprehensive guide to rehabilitating mines in Australia. There are a number of considerations and possible methods of rehabilitation, ranging from strategic seeding to collaboration. It is important to set short term and long term goals with the inclusion of certain metrics to ensure that the appropriate steps are being taken to achieve the goals. Whilst mining will always be damaging to the environment, this damage can be minimised and in the long term, rehabilitation targets should be aimed to return land use to pre-development conditions.

References:
https://www.mining-technology.com/features/australian-mine-rehabilitation/
https://epa.tas.gov.au/epa/water/remediation-programs/mt-lyell-acid-drainage-remediation
https://www.mining-technology.com/features/featuremanaging-australias-50000-abandoned-mines-4545378/
https://cosmosmagazine.com/geoscience/australia-s-rehabilitation-of-abandoned-mines-offers-lessons-for-the-world
https://www.dmp.wa.gov.au/Environment/Abandoned-Mines-15518.aspx
https://theconversation.com/what-should-we-do-with-australias-50-000-abandoned-mines-18197https://www.abc.net.au/news/2017-02-15/australia-institute-report-raises-concerns-on-mine-rehab/8270558
https://www.couriermail.com.au/news/queensland/copper-contamination-from-the-abandoned-mt-oxide-mine-near-mount-isa-is-turning-local-waterways-bright-blue/news-story/64b8038f13c13e1b070c949585ba8b45?sv=de5801fee6dc3c486b5fc09723f7f2cf
https://www.environment.gov.au/science/supervising-scientist/publications/ssr/impact-historical-mining-operations-mount-lyell-water-quality-and-biological-health
https://www.environment.gov.au/system/files/resources/adbd8065-a57a-4f29-a151-ae5edea65496/files/ssr118.pdf