Ground Gas and Coal Mine Gas
Ground gases on brownfield land or on land in the coal field can be excessively hazardous due to historic human activity including ground disturbance, waste deposition and mining. Unlicensed landfills have long been known as a source of hazardous concentrations of gases such as methane and carbon dioxide.
Most commonly hazardous ground gases are generated from biodegradation of buried organic matter, which can be found on all kinds of disturbed and brownfield land. In some cases it can be generated in hazardous concentrations and exceed thresholds for explosion and asphyxiation. Elevated risks occur when hazardous concentrations of ground gases can come into contact with development, occupied and inhabited buildings.
Development planning on brownfield land thus needs to be informed by an evaluation of ground conditions for the risk of ground gas. Guidance and procedures are well developed for ground gas investigations (BS8576), design of protection measures (BS8485) and testing and verification of protection systems (Ciria 736).
In the Development High Risk area of the coal field development planning needs to be informed by an appreciation of mineral stability risk. A coal mine gas risk assessment is usually required.
Millard provide services to clients at all stages of the process. We take an informed evaluation of risk to guide recommendations for making land suitable for use.
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