Abstract This paper identifies potential sources, and the key chemical properties, of methane. Guidance is provided on deriving a conceptual site model for methane, utilizing various lines of evidence to inform a robust, scientific, reasoned and logical assessment of associated gas risk. Discussion is provided regarding the legislative context of permanent gas risk assessment for methane, including via qualitative, semi-quantitative and detailed quantitative (including finite element modelling) techniques. Strategies for mitigating risks associated with methane are also outlined, together with the legal context for consideration of methane both in relation to the planning regime and under Part 2A of the Environmental Protection Act 1990.