Ground gas health and safety monitoring during drilling and grouting of former mine workings

Principal contractor
August 2023
Project description

The site comprised a new railway station. As part of the development works, there was a requirement to remediate former coal workings through a programme of drilling and grouting. It was recognised that during these intrusive works, there was a potential risk of hazardous ground gas emissions due to the introduction of preferential pathways and displacement of ground gas.

Prior to commencement of the drilling and grouting, there was a requirement for a safe system of work to be in place to manage the potential ground gas risk. GGS developed a system of control measures for a range of gases of concern, inclusive of RAG ratings and action levels. Subsequently, GGS supported a safe system of work by:

  • Providing daily attendance by a gas specialist during intrusive works.
  • Undertaking high-resolution gas sweep surveys prior to and post intrusive works on a daily basis, to confirm baseline conditions, ensure a safe working environment and provide an indication of any changes that may be occurring.
  • Providing a watching brief during intrusive works, with measurements of ground gas recorded on a regular basis to parts per million by volume level, to provide an early indication of potential hazardous ground gas emissions.
  • Provision and management of gas alarms, to provide a warning system and evidence to time weighted exposure.


GGS presence on site ensured that a safe system of work was in place to enable the remediation works to safely commence. Daily site records were provided to The Client to provide evidence that a safe system of work was implemented at all times.

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At GGS we provide a range of specialist ground-gas services for our clients within a variety of industries. We undertake a range of ground-gas monitoring methods, factual and interpretive reporting and consultancy.