By Jane Dottridge, David Jones, & Paul Nathanail
Geology matters. It matters in all stages of risk-based management of contaminated soil and groundwater and features in all three components of the source-pathway-receptor linkage. The ground beneath a site can be a source of natural or anthropogenic contamination. Permeable strata or structures can act as pathways along which liquids, vapours or gases can migrate. Groundwater is a receptor to be protected under several legal contexts.
All remediation strategies – be they in situ or ex situ, source removal or pathway interruption – require a detailed understanding of the relevant aspects of the ground. Excavations need to have stable sides; floor heave and incoming water need to be controlled. Gas or vapour injection (e.g. for air sparging) or abstraction (e.g. for soil vapour extraction) require a well constrained conceptual model with respect to groundwater and preferential pathways. Monitored natural attenuation depends on the physical, chemical and biological processes affecting the evolution of contaminant plumes being well enough understood to demonstrate risks are being controlled. Permeable reactive barriers need to be designed so that contaminant plumes flow through the treatment zone and not around or under the barrier.
The land contamination sector is a key part of the UK’s house building industry. While this sector is multi-disciplinary, geologists are a very large part of the professional workforce. By far the largest professional background of Specialists in Land Condition (SiLC) are chartered geologists.
The Geological Society’s newest specialist group held its inaugural meeting on 29th March 2017. As the prime minister triggered Article 50 signalling the UK’s formal intent to leave the European Union, over 150 geoscientists gathered in Burlington House to hear Society President, Malcolm Brown formally open the activities of the new Contaminated Land Specialist Group. He says: “I’m pleased to see the Contaminated Land Group become the latest Geological Society specialist group. This is an area of growing importance and one where geologists can play an important role.” Invited speakers from industry, regulators, academia and national bodies gave their perspectives on how the geosciences contribute to protecting public health and natural resources from contamination.
The Group’s first Chair, Jane Dottridge, reported that the launch of the group represented the outcome of over four years of behind the scenes work and had attracted a tremendous level of interest. More than 60 had volunteered for the group’s committee and the Burlington House lecture theatre was full to capacity. The audience represented a wide range of contaminated land professionals: contractors, consultants, regulators and researchers from across the UK with varying levels of experience, from recent graduates to the seasoned experts who wrote the original guidance in the 1970s. The group will communicate and collaborate with existing land contamination organisations, although the differentiators are geology and membership of a chartered professional institute.
Seamus Lefroy‐Brooks delivered an invited keynote presentation that reflected over the past half century of emerging national and global awareness of the adverse impacts of land contamination. He observed that the inherent uncertainty in understanding the etymological link between exposure to environmental contaminants and adverse health impacts meant that a degree of over conservatism in decision making was unavoidable. He also noted that the science is in many ways sketchy, and that not everything could be blamed on the industrial revolution. He advised the audience to neither overreact nor to assume all is fine.
Paul Nathanail recalled the fundamental role played by geologists such as Mike Smith, Sue Herbert and the late Colin Ferguson in formulating UK policy and practice in contaminated land management. He noted that the requirements for candidates for Chartered Geologist to demonstrate their understanding of the complexities of geology and of geological processes in space and time and of how to critically evaluate geoscience information to generate predictive models apply directly to risk-based contaminated land management. The conceptual site model needs to reflect the geology in terms of its role as a source of contamination, a pathway or barrier or as a receptor in its own right in the form of groundwater or geological sites of special scientific interest.
Ann Barker, giving a regulator’s perspective, reminded the audience that the contaminated land sector’s work makes a difference – by protecting public health and the environment. This is in large part due to an ethos of working together, continually striving to improve skills and share knowledge. Given the predominance of planning related work, the details of how to continue to make such differences in the context of “permission in principle” still need to be worked out.
Mark Cave gave a medical geology perspective on the effect of contaminated soil on human health. He reminded us of the British Geological Survey’s work on surveying natural and anthropogenic potentially harmful elements. BGS has also led work to characterise the effect of soil geochemistry on contaminant behaviour during exposure. Its work on bioaccessibility and bioavailability has been taken up by risk assessors in detailed quantitative risk assessments to ensure public health protection and avoid unnecessary remediation. He closed with a tantalising glimpse into a future where contaminant toxicity may be studied in silico using ‘organs on a chip’.
The meeting closed with a period of free and convivial discussion in the Lower Library.
The Geological Society’s Contaminated Land Specialist Group is rare in this country in having an Early Career sub-committee. Early career professionals are both the future and also the best ambassadors in attracting graduates into employment in an exciting and burgeoning area of work.
The Early Career sub-committee are organising our next major event, the Janet Watson Conference in November (www.geolsoc.org.uk/jwatson17). The conference series celebrates the contributions made by its namesake, Professor Janet Watson (1923-1985) – as an inspiration to young scientists, a champion of geoscience education, and the Society’s first female President. The conferences provide a platform to showcase the work of young professionals from across academia and industry, alongside presentations from role models in their sector with more longstanding experience.