Hazardous gas is considered to be any mixture of potentially explosive, toxic or asphyxiating gases, but the most notorious ground gases are methane, carbon dioxide and radon.
Assessment of potential risks associated with hazardous gas is based on a review of data obtained during the desk study.
Where the desk study indicates a potential risk from hazardous gas, Lithos are able to review monitoring data and undertake a risk assessment in accordance with current guidance.
Where the proposed development comprises low rise residential housing, the gas regime is characterized in accordance with a “traffic light” methodology. For sites classed as Amber 2, validation is required to confirm that protection measures have been installed correctly.
Other forms of development are characterized in accordance with “Wilson & Card” methodology. Both methodologies are outlined in CIRIA Report C665.
On completion of the risk assessment, we provide advice with respect to appropriate gas protection measures (membrane and sub-floor ventilation).