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Replenishing contaminated soils in recycled aggregates applications


This summer, Australia faced devastation from harsh weather conditions, having experienced some of the worst bushfires on record, extreme dust storms across New South Wales, flash flooding in Queensland and long periods of drought.

Every day we are living with the reality of climate change and witnessing its impact on our environment – and without stark intervention, the consequences of global warming on our climate will be felt for decades to come.

Indeed, the Intergovernmental Panel on Climate Change (IPCC) reported temperatures could rise by 1.7oC by the end of 2100 and sea levels could continue to rise globally.

There lies a delicate balance between climate and its impact on our soil, and the rate of change is having a profoundly negative impact on contamination levels.

Contaminated soils are a key contributor to hazardous waste in Australia, yet the full extent of soil contamination is not yet fully known. This is due to variants in reporting between jurisdictions and a lack of historical reporting.

The Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) reports of more than 160,000 contaminated sites nationally. Of these, it’s estimated less than 10 per cent have been remediated.

Australian soil has been contaminated with conventional and emerging contaminants for decades, including heavy metals, hydrocarbons, organic matter, and man-made chemicals.

Increasing soil temperatures from climate change and recent bushfires have led to increased soil toxicity and greater bioavailability. These weather patterns are having devastating effects on soil and will unearth years of historical contamination.

In fact, research has shown the long-term effects of climate change, with increasing floods and drought conditions facilitating the movement of soil-based contaminants and soil erosion.

A study by CRC CARE found soil erosion at a rate of 70 to 300 tonnes per hectare (tph), compared to what were defined as typical losses in the region of 60 to 80 tph.1

Our changing weather is causing the level of soil erosion to increase and dust storms will accelerate the spread of toxic pollutants in exposed soil. Indeed, according to data from DustWatch, dust storms are happening much more frequently.2

The movement of contaminants in dust storms presents huge health and environmental risks, as pollutants enter the air and water before finally settling into the soil again. Many contaminants such as lead, mercury, and arsenic can enter the food chain and be ingested by humans and with dust storms there is even more risk from breathing in harmful toxins.

Exposure to toxic contaminants can have a devastating impact on our health so we must find ways to diminish the risk.

Many argue contaminated soil sites surrounding our waterways and agriculture lands are those which urgently require remediation. Our peers in the waste industry and local government are determined to clean up years of contamination and have already successfully remediated inorganic and organic materials.

Yet we cannot do this alone, we need more to join us as we try to make Australia’s soils safe again.

Successes have been reported. Notably, it was revealed in the Commonwealth Government paper Soil: Formation and Erosion, Australia State of the Environment 2016 that soil erosion rates are “equal to soil formation rates”.

However, it remains to be seen how recent and unprecedented bushfires will affect this ratio, or by how much it will set remediation efforts back.

So how can CDE’s bespoke soil washing solutions support this soil remediation effort?

CDE’s technologies utilise a suite of mechanical, chemical, and biological processes for recovering washed solids such as sand and aggregates. Contaminants are transferred into the water phase which is effectively treated to produce recycled water for reuse within the process.

CDE’s bespoke solutions can be tailored based on tonnage and level of contaminants to ensure maximum efficiency within every project it delivers. These systems provide savings on landfill charges, prevent extra investment in waste storage equipment, and introduce new materials for reuse. 

We can no longer ignore soil contamination; we must utilise remediation technology to help us eliminate potential risk to human health and to protect the world around us. 

Dan Webber is the regional manager for Australasia at CDE Global.


1. The Lead South Australia. Climate change threatens to expose deadly soil contaminants. http://theleadsouthaustralia.com.au/industries/environment/climate-change-threatens-to-expose-deadly-soil-contaminants/

2. ABC News. Dust storms happening with record-breaking frequency. https://www.abc.net.au/news/rural/2019-12-06/dust-storms-happening-with-record-breaking-frequency/11768306

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