Old abandoned mine

By Professor Ravi Naidu, Managing Director and CEO of the crc for Contamination Assessment and Remediation of the Environment (crcCARE) and Laureate Professor and Director of Global Centre for Environmental Remediation (GCER)

Mining is one of Australia’s leading industries, contributing eight per cent to the country’s gross domestic product (GDP), and employing more than 200,000 people. With mining playing such a significant role on the national landscape – socially, physically and economically – there comes huge responsibility.

Australia is one of the world’s top five producers of iron ore, lead (Pb), zinc (Zn), gold (Au), nickel (Ni), mine sands and coal; in the past year, the industry contributed a record AU$455 billion in export revenue, accounting for two-thirds of all export revenue.

Mining operations are finite by nature and mining is only one of many land uses that can occur in the one place over time. Likewise, during development and operation, mines can bring significant social benefits to regional areas through economic development, employment, capacity building and infrastructure, but many communities are also displaced from their ancestral lands or farms, or have had their land degraded to the point where it poses a significant threat to people’s health and livelihoods.

Preventing these potential negative long-term impacts before they occur needs to be a part of every mining company’s strategy and its environmental and social responsibility.

Historically, mining companies have been able to get away with little accountability for their impact on the environment and upon affected communities – especially First Nations. In the absence of clear environmental laws setting standards and processes following mine closure, miners in the past were able to abandon their sites, leaving a plethora of headaches for future generations and safety hazards including contaminated land and water, which killed wildlife and impacted the livelihoods and health of local communities.

There are approximately 80,000 abandoned mine sites around Australia that have created a serious environmental, social, and economic burden. This is a picture seen worldwide; with approximately 500,000 abandoned mines in the US, at least 10,000 in Canada and at least 1,500 and 12,000 old coal mines, respectively in the UK and China.

Thankfully there has been much improvement over the past few decades in both mine design and in the management of mine closures, discouraging operators from simply walking away and abandoning mine sites.

Worldwide, ESG (environmental, social, governance)-focused regulations, codes and principles now influence mine design, development, operation and closure. The aim of these ESG frameworks is to navigate and balance the long-term benefits to people and the planet as well as making a profit in the short term.

Making ESG a priority

The roots of ESG go back to the 1960s when socially responsible investing was first introduced. This approach has grown as investors have demanded increased attention to ESG-related matters. Nowadays, the industry is subject to considerable scrutiny, both from within the environmental science research community and from government bodies who actively monitor the industry’s trajectory towards sustainable development. However governing policies vary widely from state to state and territory, and adherence to ‘best practice’ is unfortunately still optional.

The Minerals Council of Australia is publicly committed to the development of policies, strategies and partnerships that support and improve mining’s ESG performance; these include climate change action plans, water accounting frameworks, tailings management, First Nations partnerships, commitment to sustainable development, site-level ESG management and performance and more.

Companies currently need to demonstrate to regulators that rehabilitation objectives have been met before their bond is returned and mined land can be divested. However, too much is still left to the discretion of individual companies: for some, social and environmental sustainability are central to their operations, while others do the bare minimum.

Two things that would radically improve the situation are:

  1. Currently, all states and territories have different governing policies regulating the industry; harmonising these would enforce a more uniform approach on company managers
  2. Companies need to recognise that investing in research will not only ensure we protect the environment and local communities with the best new methods and technologies, but will also return huge financial savings later on during mine closure

The direct impacts of mining on the environment can be divided into two categories: firstly, physical impacts, such as land clearance, excavation and the movement of topsoil; secondly, chemical impacts from spillages of oil or petroleum, mine drainage and contamination from the use of foams and solvents.

All mine sites have been physically degraded by excavation, erosion and land clearing; most will also have been chemically contaminated.

Unpacking mine rehabilitation

Sites that have been physically degraded topsoil cleansed and replaced and water courses and hydrology restored.

The removal of topsoil means loss of organic matter as well, which in turn has implications for carbon sequestration. For rehabilitation to happen effectively, assessments need to be made on the state of these sites at an early stage – preferably before mining begins – their geographic location and their likely future uses. These factors will determine whether native species will be planted, or whether it’s preferable to use introduced species. Whichever is chosen, a small parcel should be revegetated first to determine optimal growth conditions, then when that’s achieved, larger scale revegetation can proceed.

We know that planting trees into a disturbed slag heap doesn’t work, so symbolic careful attention must be paid to associations, such as soil rhizobia and microfauna essential to sustaining native surface vegetation.

While it’s impossible to take a site back to its original state, ideally it should be returned to a comparable state – or one suited to future uses, such as agriculture. Revegetation is a slow process, so even successful, the indirect impacts upon climate change from loss of (carbon-sequestering) trees, increasing net emissions over so many years, must also be calculated when assessing environmental impacts.

This is where building an ESG approach into the early design phase of mine development is essential. A green approach that focuses on minimising emissions and erosion will reduce land degression and assist rehabilitation and hence reduce net carbon and other emissions.

Characteristics of mine remediation

Where chemical contamination (for example, due to the production of toxic dust or acid mine drainage) has occurred as well as land degradation, a mine site will also need remediation.

This is done by first assessing the site and the severity of contamination, before proceeding with clean-up. Factors that need to be considered include the relevant governing policy (which varies according to state or territory),assessment of risks and an estimate of the threshold required to create a safe and healthy environment. These thresholds will vary depending upon the geographical, environmental, economic and social location. For example, nearby fragile coastal ecosystems, farms or residential properties will demand much tougher thresholds in order to ensure no undue risks are allowed.

Clearly there is no one-size-fits-all approach. Closure of mine sites will always require a carefully tailored approach, taking into account whether sites need rehabilitation only, or remediation as well; the attributes of the natural ecosystem; its proximity to communities and its likely future land uses. This means there is no off-the-shelf solution and that approaches will vary site by site. However, today we have the ability to convert technologies based on site specific details, enabling a generic response.

Unfortunately, discrepancies in policy between state and territories create confusion and variability in interpretation of what may be required, which means that many mining companies have to operate under different sets of often conflicting rules.

A uniform national approach to rehabilitation and remediation of mine sites across Australia is urgently needed. Also, while there are policy end points determining what is require when remediating land after mining, we currently have no policy end points for land rehabilitation. This means rehabilitation is often largely left to the discretion of individual companies and their social conscience. This needs to change.

Terrain with mining waste fillings, working machinery and high-density geomembrane cover.

The residual impacts of mining operations

Where rehabilitation and remediation are not performed or are performed inadequately, the impacts can be extensive and very long lasting (Iron Mountain Mine, in Northern California, is one famous example. Mining operations ceased there in 1963 and it’s still considered one of American’s most toxic waste sites).

Areas of land, water and surrounding water bodies where mineral extraction and ore processing have taken place result in significant environmental damage.

Land clearing and excavation increase erosion, altered landscapes change water flow, and the loss of vegetation causes a net increase in emissions due to the carbon sequestering function of vegetation.

Mine waste comprises metalliferous and non-metalliferous materials generated from tailings, wastewater, acid runoff, waste sand, silt, clay, millings, drilled muds, crushed gravels and rocks, dust and powdery waste. This waste can contaminate topsoil, which is then released into the atmosphere and hydrosphere. Mine voids fill with water, creating pit lakes that present serious water quality problems such as acidity and toxicity.

Environmental contaminants are also released into the environment as a direct result of mining operations, such as grinding, concentrating areas, and disposal of tailings and wastewater.

Mines that have not been satisfactorily closed pose real and ongoing threats to human safety, health, and the environment, making them a primary global concern. These mine sites contain abundant metal sulphide minerals and, long after mining has ceased, these zones continue to release toxic materials and liquids from their built-up residue, posing a dangerous hazard to humans, wildlife, air quality, ground and surface water. These high-density heavy metal(lid)s are also persistent toxic chemicals, meaning it cannot be assumed their dangers will dissipate over time; they are bioaccumulative, and will work their way up the food chain, potentially affecting humans. These factors therefore not only negatively affect wildlife but also the people, communities and industries
reliant on these resources.

The extent to which companies invest in environmental sustainability research varies widely and depends upon internal corporate governance. It’s unfortunate that environmental sustainability currently depends too much on the attitudes of individual managers (who may have little or no expertise in sustainability) and the influence of environmental officers within each company.

Some companies remediate land after mine closure, but not all of them. Some are very focused on implementing an ESG framework while, for others, research and implementation of ESG principles is less important, and they only carry out the bare minimum. There is currently no national oversight or yardstick for measuring company performance.

At crcCARE, our partners benefit directly from the support and guidance we provide from a rehabilitation and remediation perspective. If these principles are taken seriously from the early design phase, companies find they can reduce rehabilitation and remediation costs later on, as well as curbing the risks of more serious impacts on the environment and communities, especially First Nations. Unfortunately, some companies still retain an old- fashioned view that these issues are secondary to ‘core’ business; however there is mounting evidence that this kind of approach leads to greater risk of environmental damage, negative impacts on communities, protracted and far more expensive closures and potential legal costs and reputational damage.

BHP is one example of a company that takes ESG seriously. It is very focused on research and investing in the science that underpins sound ESR policies. The company’s funded research has enhanced the body of knowledge on forever chemicals and their effects on groundwater quality, soil ecotoxicology, petroleum and hydrocarbon remediation and the development of technical guidance for clean-up of petroleum and hydrocarbon contamination. By investing in this research, BHP is creating a more environmentally sustainable company, reducing future risks and costs, and building better relationships with communities. Furthermore, its research also benefits other companies.

These days, an ESG approach is not only seen as preferable for investors on conscience grounds, it’s also a way of mitigating risk, cutting costs and identifying new opportunities. Australian governments now need to start developing a standardised approach to mining rehabilitation and clean-up across the country. Mining companies also need to work with each other on this front, sharing knowhow and technology, as the industry overall will benefit significantly if they combine their efforts on research.

The ability to successfully rehabilitate and remediate mined areas is fundamental to the mining industry’s social licence to operate.

Companies will find that by investing early in the best new ways to do this, they save money in the long term, increase their standing in the community and, importantly, protect the environment and the communities who depend upon it.

Mining companies who are interested in joining crcCARE can find more information at www.crccare.com


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