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]. To join a sub-group you must be a member of SoBRA.

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.

Poster Submissions for the 2024 Conference can be found here.

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.

Vapour Intrusion and Risk

Assessment of risks to health from volatile compounds in soil and groundwater is frequently undertaken by comparing their concentrations to generic assessment criteria (GAC). Although it is well understood that these are typically conservative, there is currently a lack of established UK standards against which to compare soil vapour concentrations, or information on other vapour assessment approaches.

A previous soil vapour subgroup published reports in 2022 on understanding the vapour Conceptual Site Model and vapour sampling. This revived subgroup aims to build on recommendations of the previous subgroup by:

  1. Reviewing and summarising available information on ‘screening distance’ approaches to assessing vapour risks.
  2. Developing and publishing Soil vapour GAC. A key element will be to highlight the key assumptions within the CSM so that assessors are able judge whether it is appropriate to use the vapour GAC.
  3. Vapour DQRA Guidance. The sub-group will produce a detailed report that reviews and summarises globally recognized approaches, methods and models for carrying out vapour intrusion risk assessments.

Members were invited to be part of this sub group in 2025.

Please see the Terms of Reference for further details.