Ground gas and vapour – An update on assessment for brownfield development, Exeter

17 November, 2016 | 18:00 - 20:00

Ground gas site.
Ground gas site.

About this event

In 2014 and 2015 three key pieces of gas / vapour guidance were published in the UK: BS8485, CIRIA Report C735 and CIRIA Report C748. Collectively these publications should aid practitioners in completing pragmatic, robust and scientific risk assessments for both permanent gases and vapours.

The truth is that, when it comes to the assessment of gas and vapour risks, often the fundamental requirements of risk assessment are overlooked. For all sites, the Conceptual Site Model is king. It allows appropriate design of site investigation and of gas monitoring wells. Everything else that follows, the risk assessment, the calculations, the modelling, they are all useless if the Conceptual Site Model is not robust.

Robust assessments should consider gas / vapour risks using multiple lines of evidence just like any other contaminant, consistent with UK Guidance as outlined in CLR11. Use the TOC approach and CLAIRE RB17 approach to reduce the amount of gas monitoring and time scales of investigations, allowing efforts to be focussed on sites where there is a real risk of gas migration into buildings.


Steve Wilson, Technical Director and Sarah Mortimer, Principal Engineer at The Environmetal Protection Group. Authors, co-authors and contributors to national guidance documents and specialist consultants advising on ground gas risk assessment and remediation and design.


Ian Cutler

The Geological Society