Written by John Russell and Dr Dawit Bekele. Published in e-cronicle in April 2025.
Soils are a limited, non-renewable natural resource and should be used and managed in a manner that is sustainable across Australia’s regulatory jurisdictions. The DCCEEW National Waste Policy Action Plan 2024 (DCCEEW, 2024); NSW EPA Towards a Circular Economy: enhancing the NSW resource recovery framework (NSW EPA, 2023); NSW EPA Guide to the NSW Resource Recovery Orders and Exemptions Policy Framework (NSW EPA, 2024a); NSW EPA Orders and Exemption Application Guideline: Applying Waste to Land (NSW EPA, 2024b) outline an ambitious regulatory framework to maximise soil re-use. Further to this, the use of certain construction and demolition waste streams are also considered as potential ‘soil’ or ‘engineering fill’.
Soils / fill excavated from contaminated sites and/or derived from construction and demolition waste streams, irrespective of the contaminant-loading, have in the past, been perceived as a waste, destined for costly and capacity-limited landfills. Careful risk-based assessment can be used to assess and characterise soils sourced from contaminated sites and/or construction and demolition waste streams to facilitate beneficial re-use, as appropriate.
Novel regulatory frameworks have been in place in other countries facilitating off-site treatment followed by beneficial re-use of contaminated soils. For example:
- The New York, Clean Earth soil treatment and recycling facilities using “thermal desorption technology for the remediation, recycling, and beneficial re-use of contaminated and uncontaminated materials including soil, stone, dredge, mine tailings, paper mill sludge, and much more.”
- UK ‘soil hospitals’ / treatment facilities which accept and treat various excavated materials / waste streams / dredged materials. The facilities use various treatment / remediation techniques to process soils for post-treatment beneficial re-use.
In Australia, similar facilities are becoming established under a similar ‘circular economy’ philosophy, such as:
- A facility in VIC offering waste material processing via thermal treatment and soil washing solutions.
- Facilities in NSW offering receipt, processing and beneficial re-use of ‘general solid waste, recyclable’.
Caution is necessary in the receipt, characterisation, treatment and re-use of these materials. In NSW, resource recovery orders (RRO) stipulate how generators characterise their “resource recovery waste” for beneficial re-use and resource recovery exemptions (RRE) stipulate the end use conditions of these materials. From a risk-based perspective, consideration should be given to contaminants of potential concern (CoPC) associated with input waste streams and these could vary from the generic CoPC testing regime recommended for the respective RRO.
The testing regime and scope of analytes for waste streams such as “recovered fines” should be based on a robust risk-based framework. Construction and demolition waste streams can often contain traces of asbestos from a multitude of now phased-out building products, polychlorinated biphenyls (PCB) in electrical equipment, polybrominated diphenyl ethers or (PBDE) (flame retardants) in wires and cables, mercury in light bulbs and fixtures, lead paint and wood preservatives containing heavy metals (Molla et al, 2024), posing challenges to be managed by recyclers. Hence the incoming materials’ sorting becomes the crucial point to screen certain high-risk items / loads out. Robust quality control testing of the end product(s) should, however, be the ultimate check to provide the community confidence in products (soils / engineering fill) being sold to the market.
The asbestos-in-mulch issue in NSW was a sage reminder that compliance requirements and regulatory oversight are necessary to ensure that CoPC in the products being sold to the market are appropriate from a contamination risk-perspective.
Construction materials like PVC, insulation foam, and paints can degrade into microplastics, which also represent an emerging contaminant risk. Health standards (thresholds) and testing methods for microplastics are currently lacking, however, it is possible that these could be established at some point and regulatory frameworks will need to be sufficiently agile to accommodate the evolution of the science. The example of how per- and polyfluoroalkyl substances (PFAS) in PFAS-impacted soils is dealt with under the HEPA PFAS National Environmental Management Plan 3.0 (HEPA, 2025) forms an excellent risk-based framework for other emerging contaminants.
The evolving framework discussed for NSW, as with other jurisdictions, should be underpinned by risk-based principles including adequate risk-based thresholds for common CoPC and emerging CoPC for treated and recycled products, reflective of the end-use risk profile (e.g. engineering fill for infrastructure projects vs topsoil for residential backyards).
In summary, soil from contaminated sites along with suitable demolition materials should be prioritised for treatment and re-use under a risk-based framework to minimise landfill reliance and support sustainable land use. Evolving regulatory frameworks around the beneficial re-use of remediated / treated soils and/or engineering fill products derived from various waste streams represent an opportunity for contaminated land practitioners, regulators and related industries to make a meaningful change by contributing to the circular economy.
Reference:
Molla et al (2024). Sustainability and Toxicity of Building Materials.
DOI: https://doi.org/10.1016/B978-0-323-98336-5.00027-3
John Russell (CEnvP-SC)
John Russell is a Principal Scientist with over 20 years’ experience in environmental consulting at Douglas Partners. John has received a BSc, MEnvSc&Law and MSc and maintains a focus on risk assessment and remediation of complex contaminated sites in Australia for public and private sector clients. John is currently a member of the ALGA risk assessment special interest group.
Dr Dawit Bekele (PhD, CPEng, NER, RPEQ, CEnvP-SC)
Dr Dawit Bekele is experienced environmental engineer and scientist with over 22 years’ of expertise in contaminated land assessment and remediation across Australia. He specialises in the fate and transport of subsurface contaminants, vapour intrusion, and contaminant hydrogeology. He is a CEnvP-SC, a CPEng with Engineers Australia, and a Registered Professional Engineer of Queensland (RPEQ).