In 2011, SoBRA established a number of sub groups to work on specific topics with the aim of providing guidance and tools of potential benefit to land contamination practitioners. The sub groups operate in accordance with SoBRA’s procedure document.

Our currently active sub groups are listed below. If you would like to become involved in a sub group then please email: [email protected].

Members can suggest topics for new sub groups using this form

Non-Aqueous Phase Liquids

The evaluation of contaminated land risk relies on understanding sub-surface processes. Non-aqueous phase liquid (NAPL) can be difficult to measure, meaning conceptual site models (CSM) may be data deficient.  Following several requests from our members, SoBRA has created the NAPL sub group. The aim of the NAPL sub-group are to support technical excellence in the assessment, estimation and evaluation of risks associated with NAPL, and to encourage best practice by delivering practical advice to support decisions regarding the appropriate management of NAPL risks.

The sub group aims to avoid reproducing the wealth of existing NAPL guidance but instead provide clear practical advice that can be applied to the various stages of site assessment: including introductory context for the UK approach and regulatory signposts, development of a solubility spreadsheet, a NAPL mobility screening tool, information on options for monitoring and their respective pitfalls, interpreting results from bail down tests, NAPL transmissivity and residual saturation, and a guide to remedial options for NAPL.

Members were invited to be part of a sub group in 2019.  Please see the Terms of Reference for further details

Ground Gases

The focus of the ground gas sub group is to improve the quality ground gas risk assessments delivered by the industry. Currently many assessors only consider gas monitoring results with little attention given to other equally important data. Members are currently working on three projects that have been prioritised by the group:

  • a road map or tool box of the guidance on ground gas investigation and assessment;
  • advice sheet on developing and using conceptual site models for gas; and,
  • advice sheet on how to calculate gas mass flux rates and to screen out “no risk sites”.

Anyone with an interest in ground gas is welcome to join.
Please see the Terms of Reference for further details.

Early Careers

A new early careers subgroup was requested by our members for 2021. The aim of the subgroup will be to provide advice and training opportunities for early careers professionals within contaminated land, raise awareness of key guidance documents, and provide mentoring and networking opportunities for early career professionals. The aims will be delivered through hosting webinars and workshops.

Please see the Terms of Reference for further details.

Controlled Waters and Climate Change

A new controlled waters and climate change sub group was requested by our members for 2021. The need to incorporate the effects of climate change into qualitative and quantitative risk assessments is set out within Managing and reducing land contamination: guiding principles (GPLC2) FAQ 8, 2010, and the National Planning Policy Framework. However, there is currently little guidance on how to consider the effect of climate change on land contamination. The aim of the sub group was to provide clear practical advice on how to include for the potential effects of climate change in the assessed stages of land contamination controlled waters risk assessment.

Please see the Terms of Reference for further details.

Update: The sub group completed its work in August 2022 with the publication of its report, Guidance on Assessing Risk to Controlled Waters from UK Land Contamination Under Conditions of Future Climate Change.

CSM and Statistics

The CL:AIRE “Guidance on applying statistics to land contamination decision-making” publication (September 2020) emphasised the importance understanding the Conceptual Site Model (CSM). To support the risk assessment community in understanding what this might mean in terms of soil chemistry / chemicals, SoBRA proposed to develop and publish a discussion paper outlining key considerations and steps an assessor should consider when developing a CSM which can provide a good foundation for further/future data analysis.

The objective of the (short-term) subgroup is to provide a good practice guide regarding how the conceptual model and soil contamination data interface with each other. The intention is that assessors could use the guide each/every time they assess data and develop/refine conceptual model(s), and may include some other approaches that might be useful to consider given particular circumstances.

The good practice guide hopes to include some demonstrations/examples (case studies) showing how simple data analysis can be a useful additional tool for a risk assessor when interpreting chemical concentration data for soils.

Please see the Terms of Reference for further details.