A sustainable approach to soil
Given its organic nature and universality, it can be easy to think of the soil around us as a renewable resource. However, the truth is that the lengthy development period and the combination of several important natural factors in its formation mean that soil is essentially non-renewable. Due to its vital contribution to food security and future sustainability, there is growing recognition of the fact that – like all the world’s resources – soil needs to be protected and used appropriately.
This is reflected in both soil’s inclusion in the United Nations’ Sustainable Development Goals (see Targets 3.9, 12.4 and 15.3) and the European Union’s monitoring of the ‘Status of local soil contamination in Europe’.
Unfortunately, soil remains under increasing environmental pressure across the globe. The EU’s monitoring report also suggests that “the associated soil degradation is raising extreme values in Europe due to a high population density and its related activities, such as industrial activity, inappropriate agricultural and forestry practices, tourism and urban development”.
Of particular importance to the resource management industry should be the protection of soil through the reduction and removal of organic and inorganic contaminants, including heavy metals or manmade contaminants, rather than the removal and disposal of the soil itself, with the associated landfill issues. The EU has reported that there are a possible 2.8 million sites in the EU-28 countries where polluting activities have taken or are taking place, so this is a huge opportunity for the industry.
In Germany alone there are estimated to be around 300,000 potentially contaminated sites, of which the German environmental agency (Lander) estimates that between 10-15% need remediation. This would mean there are between 30,000 and 45,000 sites in need of attention. In addition, there are 29,000 sites in Germany either currently or formerly used for military purposes which may be contaminated.
Progress is being made to tackle the issue. In the EU, more than 5,000 new sites were under remediation between 2011 and 2018 when data was last recorded and published. It is also believed that more than 65,500 sites have already been remediated or are undergoing aftercare measures.
Three main challenges
There are three main challenges that can prevent effective land remediation, the main one is, perhaps unsurprisingly, cost. Although the polluter pays principle (PPP) applies, it is often hard to identify the relevant party either due to the contamination type or the length of time since the contamination took place. Where new contamination is concerned, PPP is usually applied, but the EU reports that 42% of total remediation expenses come from public funds to cover historic contamination issues.
The need for public funds impacts the second issue, political will. There is no specific European legislation that would ensure the consistent investigation and remediation of contaminated land. This means a variety of national, regional and local policies have been implemented as deemed appropriate by the relevant authorities. While some authorities have been attempting to tackle contamination for decades, for others it is a much newer issue to address.
The Sixth Environment Action Programme of the EU determined that soil protection against adverse impacts should be a priority for Europe and, subsequently, both social and political awareness of the importance of soil has risen. In addition, the UN Environment Assembly resolution, UNEA3, calls for global action on soil-pollution prevention and control and the remediation of contaminated soils. The action was adopted by 170 countries and should further strengthen and improve remediation efforts.
The third challenge is the most relevant for the resource industry; making the technology to remediate soil accessible and affordable.
As well as being present in soil and potentially causing issues through direct contact or airborne transmission, contaminants can leach into water sources and lead to direct contamination of human drinking sources, the bioaccumulation of chemicals in animals which can eventually make their way into the food chain, or adverse health complications due to their presence in land used to grow arable and horticultural crops. Therefore, removing pollutants and contaminants in the soil is vital to ensure safety for humans and wildlife.
Thankfully, the industry’s knowledge of current and emerging contaminants is increasing and so is our ability to treat them.
Wash and go
On-site equipment solutions are now available that wash and treat contaminated soil and sludges, including removing heavy metals, hydrocarbons and, of growing recent concern, Per- or poly-fluorinated alkyl substances (PFAS). These industrial chemicals are used in a variety of processes including the production of non-stick pans and clothing for example and are extremely difficult to break down because of the carbon-fluorine bond in their molecular structure.
Eunan Kelly, Head of Construction, Demolition & Excavation Recycling at CDE, says: “Taking on the multitude of contaminant challenges requires a suite of mechanical, chemical and biological processes. Our fully integrated solutions combine the soil treatment process with advanced tertiary water treatment systems to make the decontamination process as efficient and effective as possible.”
This means washed solids such as sand and aggregates can be recovered by transferring contaminants into the water phase and effectively treating them to produce recycled water for reuse within the process.
Each solution should be flexible to meet the individual situation. Eunan adds: “CDE’s bespoke solutions can be tailored based on tonnage of soil to be treated and level of contamination present to ensure maximum efficiency within every project we deliver.”
“By removing the majority of the contamination from the remediated land, the majority of what remains can be reinstated or recycled,” Eunan explains. The treated, clean soil is suitable for use in property expansion and redeveloped land; as a sustainable source of backfill for contractors or for clean aggregate and sand suitable for reuse.
Alongside the improved soil quality, the appropriate remediation systems provide savings on landfill charges and prevent extra investment in waste storage equipment.
Importantly, these systems also extract materials for reuse. By recovering 80-100% of materials from what would be considered waste, soil remediation can increase revenue and preserve our valuable natural resources.
For more information about CDE, visit CDEGlobal.com.