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Ground Gas Risk Assessment

Ground gases can be generated by a variety of natural and anthropogenic sources such as peatland and marine alluvium with high organic matter contents and landfill sites. The typical gases that are monitored as part of a ground gas risk assessment include carbon dioxide, methane, hydrogen sulphide and carbon monoxide. We can also provide short or long term monitoring of radon gas concentrations.


A lack of understanding of the required assessment can often result in project delays and/or the installation of over-designed protective measures. Our ground gas assessments are undertaken according to guidance found in BS 8485:2015+A1:2019 and CIRIA C665 and are specific to each individual site and the ground conditions encountered therein.

At DAM Geotechnical Services we usually include a ground gas risk assessment as part of our Phase II site investigation reporting, although we can also undertake this as a standalone exercise. We will also include detailed recommendations of any gas protection measures required (if any) to achieve the correct 'points score' for the development, as defined in BS 8485. We can also offer supervision and validation of the installation of any ground gas protection measures in order to satisfy the requirements of the Local Authority.

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