Article provided by Paul Nathanail (GHD), Claire Dickinson (Geo Environmental Matters) and Dr. Tom Henman (RSK Geosciences)
Climate change is causing extreme weather events – more intense precipitation, flooding events, prolonged droughts, extremes of temperature, prolonged periods of high or low temperature, more intense storm events leading to frequent and stronger winds and steeper drops in atmospheric pressure. In their pioneering presentation at the 10th Congress of the International Association for Engineering Geology and the Environment, held in Nottingham, Judith Nathanail and Vanessa Banks (2009) highlighted the effect of climate change on land contamination, among other aspects of engineering geology. These changes will influence the way we manage land contamination and carry out site investigations, risk assessments and design, undertake and verify remediation.
As well as influencing slope stability and rates of soil erosion, these events will affect the ground and hence the risks posed by chemical contaminants in the soil, water, non-aqueous and gaseous phases. The strength, deformability, permeability and durability of ground will change. Prolonged droughts will deepen and widen desiccation cracks in high plasticity soils. More intense precipitation will saturate and weaken ever deeper soils. There will also be effects on the water table. Higher temperatures will increase rates of chemical absorption rates, weathering and biological activity.
Extreme weather events will alter the behaviour of contaminants. Increased volatilisation will result from the higher vapour pressure of volatile organic compounds (VOC) resulting from higher temperatures. Most ground gas related incidents relate to very large falls in atmospheric pressure so their occurrence may increase unless adequately mitigated
Higher temperatures and more precipitation resulting in faster weathering could capture inorganic carbon in carbonate minerals. Increased dissolution could release nutrients stimulating microbial activity such as hydrocarbon degradation. Heavy metal mobility can increase by acidification as more carbon dioxide dissolves in rainwater.
Remediation works will be disrupted by sudden downpours. Wet, slippery conditions increase wear and tear on tyres and make working conditions more dangerous. Worker and public safety will be threatened by stronger winds picking up hoardings or loose materials and equipment.
Risk assessments, remediation design and choice of construction materials must be resilient to modelled climate scenarios, such as extreme summer and winter temperatures and increased precipitation intensity. The probabilistic UK Climate Projections (UKCP18) are based on a limited number of future greenhouse gas (GHG) emission scenarios. Land contamination professionals will need to ensure that an appropriate range of future GHG emission scenarios have been taken into account.
In the UK, a professional is usually identified by being a chartered member of their relevant body. A chartered practitioner has demonstrated a high level of knowledge, skills and experience, and is bound by a strict code of professional conduct.
A SiLC is a senior professional with the broad awareness, knowledge and understanding of land condition to provide impartial advice in the SiLC’s field of expertise. The SiLC Register lists professionals from the range of professions relevant to land condition matters. SiLC is also the approving body for SQPs able to sign declarations of document adequacy under the National Quality Mark Scheme (NQMS). The Register is managed by the Professional and Technical Panel (PTP) of representatives from relevant professional bodies.
There is always uncertainty within site assessments and considering potential climate change impacts should be as site-specific as possible and based on available regional or local climate projections. The NQMS mandates consideration of uncertainties and the implications for both the site assessment and decisions taken on next steps.
For climate change to be effectively accommodated in land contamination risk management, each profession needs to ensure its insight into the effects of extreme weather effects are considered at each stage of a project. SiLCs are well placed to contribute to such multi-disciplinary assessments and advise on the wider implications for the project.
The authors are members of the SiLC Professional and Technical Panel. For more information on SILC please visit www.silc.org.uk
You can also contact Paul via email: firstname.lastname@example.org
Nathanail, J. & Banks, V. 2009 Climate change: implications for engineering geology practice. In: Culshaw, Martin; Reeves, Helen; Jefferson, I; Spink, T.W., (eds.) Engineering geology for tomorrow’s cities. Geological Society of London Engineering Geology Special Publication, pp 65-82, 17pp. Available at: http://nora.nerc.ac.uk/id/eprint/9308/