Future proofing Australia's engineered landfills

Australia is making significant strides in sustainable waste management, with a renewed focus on increasing diversion, reuse, and recycling opportunities. In 2022-23, Australia generated approximately 75.6 million tonnes of waste (1), with 63% of this waste recovered for reuse, recycling, or energy (2). However, recent state strategies like Victoria’s Recycling Infrastructure Plan 2024, the draft Queensland Waste Strategy 2025-2030, and the draft NSW Waste and Circular Infrastructure Plan 2025, reveal that we still rely heavily on engineered landfills. This will likely continue until alternatives, such as energy from waste facilities, are more widely available. 

As we transition to a more circular economy, engineered landfills will play a critical role for disposal of wastes that cannot be recycled or used to create energy, and for the ash and combustion products from energy from waste facilities that cannot be repurposed. Therefore, any disruptions to landfill operations could have serious consequences. It is therefore critical that we anticipate and address various change drivers that might impact on the design and operation of landfills in the future. We explore these further below:

As a result of initiatives and opportunities such as food organics and garden organics diversion, along with further implementation of energy from waste, and a drive for circularity, the composition of waste disposed to landfill is slowly changing. Experience in the UK suggests that this brings new challenges, for example removal of recyclables can change the physical structure of compacted waste. Landfill gas composition can change with less food organics being present, and the chemical composition of leachate can also change, and may require upgrades to systems already in place to manage these byproducts.  

Residual wastes of certain types will need bespoke containment solutions. Based on our long-term experience in industrial and hazardous waste facilities, we predict an increased focus on site-specific and long-term performance testing for landfill liner material selection. This will be based on waste and leachate characteristics and the development of more sophisticated containment, drainage collection and treatment systems to meet this demand. This may include additional safeguards such as leak detection layers to identify and manage any issues with containment systems if they arise.  

One of the biggest challenges facing waste management is how to safely manage emerging contaminants such as PFAS (per- and polyfluoroalkyl substances), the “forever chemicals”. These chemicals, which repel water, oil and heat, may pose significant risks to human health, and are known to be present in the waste that is landfilled. Their extremely high mobility means they can migrate into landfill leachate and potentially escape into the environment. Landfill leachate is often disposed to sewer after pre-treatment to reduce its biological load on sewage treatment plants. For leachate management, additional requirements are already being flagged by water authorities for removal of PFAS to very low levels prior to sewer. This points to more complex leachate pre-treatment being required at landfill sites in future, such as activated carbon filtration or ion exchange. However, removal of PFAS from wastewater means higher concentrations of PFAS in residues from PFAS treatment systems.   

Research has shown that PFAS has potential to reduce service life for typical containment solutions such as polyethylene geomembranes (3). Therefore, enhancing landfill liner systems with secondary or even tertiary lining may be necessary to address this emerging issue. On a positive note, on the back of this, the industry is already heavily investing and researching new containment products that may be better equipped to combat the impacts of PFAS and other contaminants.  

Recent studies have also identified the presence of PFAS within landfill gas (4). This presents another potential contamination concern, as landfill gas flares are not currently equipped to destroy PFAS.  

For landfill owners and operators, the presence of emerging contaminants in our waste streams is not a problem of their making. Rather it is a societal issue that needs to be addressed through dialogue across multiple parties – including landfill owners and operators, environmental regulators, and water authorities. We need to drive pragmatic solutions while still protecting human health and the environment.

Climate change will drive higher standards for the design of landfill infrastructure, in particular how water flows are properly segregated and managed with consideration to higher and more sustained peak events. Recent guidelines and legislation, such as the Australian Rainfall and Runoff guidelines, have sought to include requirements to consider the latest climate science and projections for flooding and water infrastructure design. The evolving guidance will require practitioners to implement more detailed projections across the life cycle of an engineered landfill, to adequately future proof environmental management controls. 

It’s important to acknowledge the increased risk of natural disasters and their potential to generate significant amounts of waste in a short period. Effective planning will be key to mitigate the risks these events present. Landfills that may be used to manage such waste should consider comprehensive mitigation measures, including contingency capacity, to address the potential for overwhelming waste volumes and environmental hazards. Strategic consideration is essential for the resilience and safety of waste management systems during disaster scenarios.

Landfill gas recovery technologies continue to evolve, with stronger capabilities to extract stable and good quality landfill gas, improving energy yields and viability. 

In particular, the conversion of landfill gas to renewable natural gas (instead of electricity) represents an exciting opportunity. Around the world, and particularly in the USA, there has been a major uptake in the development of these facilities that produce a gas with a higher revenue generating potential, driven by market incentives such as carbon credits/offsetting. It is very likely that the same incentives will emerge within the Australian market as we continue to seek to reduce greenhouse gas emissions across the country. 

Notwithstanding this, as landfilled waste becomes more organics depleted, the landfill gas generating potential is likely to reduce and composition is likely to change. This may adversely impact the feasibility of ongoing energy recovery opportunities. These factors need to be considered as we assess potential opportunities in this space.

Technological advancements at landfills now include drone surveys and photography to monitor filling progress, as well as sophisticated instrumentation and control systems for managing leachate and landfill gas. These technologies facilitate ongoing monitoring and enable faster emergency responses. Emerging technologies, such as drones and satellites for landfill gas monitoring, are also being explored. Future opportunities, like fully remote-controlled equipment, may gain momentum in line with industry trends. 

Automation, AI, and other technologies are crucial for improving safety, performance, and compliance at landfills. However, the slow adoption of these innovations remains a challenge due to the strict regulatory environment. While consistent and stringent environmental regulations are essential, they should not hinder positive innovation. Finding the right balance is key.

We recognise that engineered landfills will continue to play a pivotal role in our waste management hierarchy into the near future. The changes that will drive their evolution are not insurmountable, and in many instances represent opportunities to improve the effectiveness of these facilities. We encourage the waste and resource recovery industry to address these upcoming challenges together so that our landfills are sustainable, safe and environmentally sound. At GHD, we are committed to supporting this effort, whether it be through our transferrable hazardous/industrial waste facility skillset, our breadth of PFAS knowledge across all facets of management, or our proven technical solutions for maximising landfill gas recovery.

1: Waste emissions projections 2023

2: Australian Waste Statistics 2025: Trends, Forecast and Insights - Aus Rubbish 

3. Rowe, R. K. & Somuah, M. (2023). Effects of perfluoroalkyl substances (PFAS) on antioxidant depletion from a high-density polyethylene geomembrane. Journal of Environmental Management, Volume 328 

4: Lin, A. M., Thompson, J. T., Koelmel, J. P., Liu, Y., Bowden, J. A., Townsend, T. G. (2024) Landfill Gas: A Major Pathway for Neutral Per- and Polyfluoroalkyl Substance (PFAS) Release. Environmental Science & Technology Letters, Volume 11, Issue 7