Better Risk Assessment For More Sustainable Developments

The climate emergency is not up for debate, it is here and brings with it serious negative impacts. Climate change is caused by greenhouse gases generated from a range of human activities – energy production, transport, industry and producing food – entering the atmosphere and warming the planet. The construction industry contributes 39% of global carbon emissions. Everyone involved in the industry has a role to play in reducing this number. We caught up with Amy Juden, a Ground Contamination Consultant for EPG, to capture her thoughts on the role of risk assessments in producing lower carbon developments.

The death rate for the climate emergency has previously been estimated at around 300,000 per year (Global Humanitarian Forum, Human Impact Report, 2009) and is continuing to rise. As contaminated land risk assessors, we deal with minimal risk thresholds for excess deaths related to toxic chemicals. The harm being done by climate change is on a much larger scale.

Recent studies have introduced a new concept – the carbon cost of a life. A recent study by Bressler, published in Nature concludes: adding 4,434 metric tons of carbon dioxide in 2020—equivalent to the lifetime emissions of 3.5 average Americans – causes one excess death globally in expectation between 2020-2100.

However, this estimate only takes into account direct temperature-related deaths, whereas climate change can also lead to other deadly environmental and related social disasters resulting in excess deaths, such as flooding, wildfires, crop failures, conflict, and mass migration. So, it is likely to be a significant underestimation.

Another ‘back of the envelope’ calculation by Mike Berners-Lee in his book “How bad are bananas?”, estimates the carbon cost of a life to be as low as 150 tonnes. Given that my personal carbon footprint per year is around 15 tonnes, by this measure my emissions could be leading to a climate-related death every 10 years. The true number is likely to be somewhere between 150 and 4,400 tonnes, perhaps a few hundred tonnes.

Remediation works are necessary for some brownfield sites to make them safe and suitable for development, but all remedial interventions have a carbon cost. However, most carbon calculators available for construction activities only focus on the structure and are not designed to calculate the impact of ground works, excavations, remedial interventions, and treatments. Nevertheless, some companies are developing their own internal tools to do this, such as the Leap CReDiT tool for soil cover layers and foundations, and carbon calculators used by SoilFix. Recent discussions at the 2023 SiLC annual forum highlighted the importance of these calculations – you can’t manage what you don’t measure, and the need for standardisation of such tools.

As contaminated land risk assessors and designers, we have the greatest opportunity to minimise the carbon impact of developments on brownfield land. Similar to the waste hierarchy we learned at primary school, where the first priority is to Reduce, then Reuse, then Recycle, when it comes to remediation, the most sustainable option is often to do nothing. Better conceptualisation of a site and using detailed quantitative risk assessment (DQRA) can make this possible, but these tools are underutilised. Over-conservative assessments lead to over-engineered designs and unnecessary remediation works, contributing to the significant embodied carbon in the construction industry.

It should be considered environmentally irresponsible to specify remediation on the basis of a generic screening approach alone, without considering further assessment that could lead to a reduction in remediation. Remediation should not be used as a substitute for adequate investigation and assessment.

Most of the rhetoric and guidance/publications on sustainability in contaminated land to date (i.e. that produced by the CL:AIRE Sustainable Remediation Forum SuRF-UK) focuses on methods to minimise operational carbon emissions during remediation works. However, I argue that we could have a more significant impact on the carbon budget of a project if we consider the carbon impact earlier in the process and eliminate unnecessary remediation at the risk assessment stage.

As risk assessors and designers, we have a responsibility to design out carbon from our development projects wherever possible, in the same way that we have a duty to design out health and safety risks under CDM.

If climate change is causing deaths now at a rate of a few hundred tonnes of carbon dioxide per death, are our frameworks for assessing risk from contaminated land fit for purpose? Do we need to rethink the precautionary principles on which we operate? It also depends on people’s attitudes to risk. Perhaps climate change is so well-known and accepted in society now that we accept the fact that people all over the world are dying in climate related natural disasters. Our appetite for health risks associated with ground contamination (i.e. toxins in our garden soils, or carcinogenic vapours in our homes or workplaces) may be different.

Never-the-less there is far more that can be done within the existing frameworks and acceptable minimal risk levels. Remediation is being over specified on the basis of theoretical risks that are poorly determined.

In summary, as contaminated land risk assessors and designers, we have the power to minimise the carbon impact of developments on brownfield land. The most efficient way to do this is by intervening early. This means that before considering remediation, we should better conceptualise a site and use DQRA to determine if no action is the most sustainable option.

This is the approach that is always taken at EPG. We pride ourselves on delivering the most sustainable solution for a site, and are never afraid of offering an innovative assessment or bespoke approach to get there. This can have the added benefit of saving our clients significant sums of money in the construction phase.

But what will the future of contaminated land assessment look like in the context of climate destruction and the race to net zero? Should we incorporate the carbon cost of a human life into a new holistic framework for construction and remediation on brownfield land that considers the need for development and remedial intervention against the actual human cost? By changing the narrative and talking about carbon footprints in terms of death rates, we can increase awareness of the urgency of the climate crisis and the need to transition to net zero as quickly as possible.

Improving standards in contaminated land risk assessment through increased use of DQRA, education and training, and new targeted research, will allow for a reduction in the carbon footprint of our industry. As well as saving money on development projects. Development of standardised tools for measuring the carbon impact of remediation works, will allow us to manage this effectively. And incorporation of the concept of the “carbon cost of a life” would allow for comparison of carbon budgets, with human health risks.

Better risk assessment is integral to reducing carbon emissions in remediation of brownfield land. Let us work together to create a more sustainable and resilient future for all.