The management of legacy environmental impacts via risk-based analysis is driving a paradigm shift in sustainable remediation.
It is estimated that Australia spends over $2 billion each year cleaning up contaminated land and water. At the same time, areas of potentially high-value urban land lie unused.
While existing on opposite ends of the remediation spectrum, the convergence of these realities highlights issues with the historical approach to managing legacy environmental impacts.
On one hand, traditional ‘dig and dump’ methods resulted in costly and at times unnecessary attempts to remove or remediate contaminants.
While on the other, would-be productive land is left unused due to a perception that the contamination is too difficult to deal with – presenting a multitude of environmental, social and economic impacts.
According to Fiona Robinson, Ramboll’s Australia and New Zealand Regional Director, understanding those impacts is critical to shifting the dial on remediation and safeguarding a sustainable and healthy environment for future generations.
Robinson, who holds a Masters in Engineering and has over 25 years’ experience in environmental science, engineering and consulting, explains that remediation strategies are undergoing a significant paradigm shift.
Once the exclusive domain of energy-intensive, mechanically driven processes, passive strategies such as in situ bioremediation, chemical oxidation and chemical reduction are emerging as integral remediation tools.
Robinson’s specific areas of expertise include hydrogeology, site evaluation and remediation design in the contaminated site field, as well as groundwater resource and impact evaluation through three-dimensional modelling.
“I have always had an interest in sustainability and felt that engineering was a good way to make a difference in terms of being able to solve problems and provide better solutions,” she says.
Robinson joined Ramboll in 2010 as a Manager at the company’s Hunter office in NSW.
In 2017 she accepted her current role as Australia and New Zealand Managing Principal, working to further diversify Ramboll’s environmental services.
While Robinson’s personal focus is remediation and environmental management, she notes Ramboll’s work in new and emerging markets for a zero emissions future, including waste-to-energy and solar and wind farm engineering.
“I joined Ramboll to be part of a global company that is aligned with what I intended to do with my career, which is to help develop sustainable solutions for the future,” Robinson says.
“As a company, that’s our focus. We’ve been working in this space for 75 years, and all of our engineering is driven by sustainability principals, which for me is great, because remediation historically has been very dig and dump. And that never seemed very sustainable.”
RISK-BASED FRAMEWORKS
Headquartered in Denmark, Ramboll applies risk-based strategies throughout the investigation, remedial design and execution process to streamline site investigation and decision making, with a focus on effectively protecting human health and the environment.
Underpinning this approach is the United Nations’ Sustainable Development Goals.
“From a remediation context, an often overlooked aspect is the Sustainable Development Goals of intergenerational equity, ensuring we don’t leave remediation for someone in the future,” Robinson says.
Ramboll engineers, geologists and scientists deliver value-added, site specific solutions that address all aspects of the remediation process – from site investigation, risk assessment and feasibility studies, to remedy selection, remedial design, environmental assessment, management and approvals
“We differentiate ourselves by providing tools to evaluate remediation projects using multi-criteria analysis that looks at environmental and social impacts and benefits,” Robinson says.
“It’s about looking more holistically at-risk profiles and being able to quantitatively evaluate a whole range of criteria to determine the optimal remediation outcome.”
Robinson explains that Ramboll’s approach is driven by a recognition that remediation in and of itself can have an impact. She adds that the sector has not historically looked at the impact of remediation, whereas now, the focus is shifting towards full lifecycle assessment.
When engineering a solution, Ramboll considers ultimate risk-reduction goals, risk management during implementation, management of long-term risk and future liabilities, and the short-and-long-term costs of various alternatives.
“Ramboll’s interdisciplinary approach to site remediation helps our clients manage the complex and interrelated issues that drive remedial decisions,” Robinson says.
HOLISTIC ASSESSMENT
In 2012, NSW’s Kurri Kurri Hydro Aluminium Smelter suspended operations, with closure announced in May 2014 following a two-year period of care and maintenance. When operational, the smelter produced 180,000 tonnes of aluminium metal each year.
Ramboll was engaged to prepare a Remedial Action Plan for the remediation of the smelter including remediation of a capped legacy landfill.
“The potential remediation options ranged from segregating and decontaminating all wastes for recycling by others, to relocating the wastes to waste repositories a significant distance from the site.” Robinson says.
Following Ramboll’s review of remediation options, it determined that relocation of the mixed waste to a new purpose-built containment cell within a more geologically suitable area of the Hydro land was the most appropriate remediation strategy.
According to the detailed quantitative studies completed, this strategy will have the least impact on the health, diversity and productivity of the environment.
Additionally, the containment cell will facilitate the needs of future generations, by making the Hydro land suitable for future use including employment land, residential land, rural land and a large area dedicated for biodiversity conservation, as well as providing financial support for the long term management of the containment cell.
These new land uses, combined with financial assurance, will provide long-term environmental, social and economic benefits, consistent with the principle of intergenerational equity.
The Hydro Aluminium Smelter remediation project is one of the first in Australia to use Ramboll’s newly developed net environmental benefit analysis (NEBA) tool, Robinson says. She adds that NEBA works to demonstrate the positive and negative impacts on natural resource services associated with a remedial action, relative to the change in risk profile.
“Risk underpins the need for remediation. All remediation is driven by risk,” Robinson says.
“You need to consider what is that risk? And when you are evaluating risk, are you evaluating all, or just part of the risk story?”
“In some cases, for example, a proposed remedial action or reuse activity may destroy or significantly degrade an ecological landscape, that outweighs the environmental or human health benefit achieved from the remediation.”
Robinson highlights communication of risk as a historical challenge for the remediation sector. To mitigate that challenge, Ramboll’s NEBA tool provides its consultants with the ability to effectively evaluate a project under a range of potential options. And in turn, be able to communicate those options to various stakeholders in a way that can be understood.
“Effective communication requires one type of conversation with regulators and another type of communication with community members,” Robinson says.
She explains that often in situ solutions are not preferred by either the regulator or the community, despite potentially providing the most sustainable outcome.
“The purpose of the remediation assessment tools we’ve developed is to build transparency in the process and make it less subjective.
“It’s a more quantitative process, where you complete a quantitative analysis and understand what the risk or benefit profile is. And because you’re taking it all from first principles, it’s easier to communicate to both the regulator and the community.”
Chemical stabilisation is another area Ramboll is focused on developing.
Ramboll’s Dr Annette Nolan has over 25 years’ industry experience in environmental chemistry and research and is currently investigating the long term stability of PFAS in chemically stabilised soils.
“When properly evaluated, chemical stabilisation, particularly in-situ, represents a sustainable and safe long term remediation solution for some contaminants. It’s exciting to have this research underway at Ramboll,” Robinson says.
“Dr Nolan’s preliminary bench scale trials of PFAS stabilisation using a range of soil amendments are showing very promising results and indicate PFAS can be cost-effectively stabilised in soil with >99 per cent reduction in leachable PFAS concentrations achieved using a multiple extraction procedure, which demonstrated good long term stability. Technologies such as these can provide great outcomes for these difficult sites.”
FIRST PRINCIPLES FUTURE
Looking forward, Robinson predicts that brownfield development will continue, alongside the development of more sensitive land uses on industrial sites. That said, she believes that remediation and contaminant levels will become progressively less severe with time.
“A lot of the heavily impacted sites are now being remediated. If you look at gasworks, we’re not creating any new sites – that’s not an emerging issue for the future,” Robinson says.
“Landfills are the area where we will have to really look at risk and clever solutions, because traditional remediation of those sites is not going to be practical. That’s already happening with urban sprawl encroaching on former landfills.”
Protection of groundwater resources will be another area of future focus, Robinson says.
“Groundwater has not historically been seen as a resource in urbanised areas,” she explains.
“We might be wanting to look at remediation solutions that afford a higher level of protection for the groundwater resource.
“And of course, PFAS contamination, which will be a whole of industry pursuit.”
At present, the problem of PFAS is dominating industry discussion, with the contentious fate of tunnel boring spoil from the West Gate Tunnel project prompting community concern and legal challenges.
While Robinson says industry has a long way to go before fully understanding the risk of PFAS, Ramboll is committed to working on viable solutions.
“We have two research projects at the moment looking at PFAS destruction in water streams. One is an ex-situ approach, and the other is looking at a potential in situ treatment process,” she says.
“We have a global team working on sustainable solutions for these and other emerging contaminants.”
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