Coal Mining Risk Assessments

What is a Coal Mining Risk Assessment?

A Coal Mining Risk Assessment (CMRA) is a report that considers the legacy coal mining activities beneath a subject site and within the local area, to assess the potential hazards which could present a significant risk to the proposed development. A CMRA is a desk-based study which analyses published records from the likes of the British Geological Survey and Mining Remediation Authority to gather an understanding of the complex geology and assess its economic potential as a historic resource.

Coal Mining Risk Assessments and Planning

Coal Mining Risk Assessments (CMRA) are often stipulated as a planning condition by multiple local authorities across the United Kingdom where the proposed development falls within a Mining Remediation Authority (MRA) ‘Development High Risk Area’ and where the MRA would be a consultee. Should the subject site not fall within a ‘Development High Risk Area’ and only a ‘Coal Mining Reporting Area’ a full CMRA may not be required. However, this will need to be assessed on a site by site basis.

Where are the Mining Remediation Authority ‘Development High Risk Areas’?

Mining Remediation Authority ‘Development High Risk Areas’ are sporadically spread across Mining Remediation Authority ‘Coal Mining Reporting Areas’. The ‘Coal Mining Reporting Area’ are located within areas of historical coal mining activity and importantly, coal bearing geological formations. ‘Coal Mining Reporting Areas’ are primarily located in the Midlands, North East and North West of England. Other notable areas of coal mining include Kent, Bristol, South Wales, and the Lowlands of Scotland.

What are the Hazards Associated with Coal Mining Legacy?

Historical coal mining activity can present both geotechnical and environmental liabilities towards any proposed development.

Geotechnically, historical coal mining can pose different issues which can affect the stability of any proposed development often through coal seam and mine shaft collapse resulting subsidence of a developmental platform. Mine shaft collapse can also pose a significant risk to human health should a deep void open at surface.

Historical coal mining activity can often leave behind high levels of contaminants such as heavy metals, sulphates and hydrocarbons which pose a risk to both soils and groundwaters beneath a subject site. In order to assess the specific risks associated with historical coal mining on a proposed development, ground investigation is often required. Which can be undertaken along side other ground investigation activities.

Disused coal mines can often provide a preferential pathway for hazardous mine gas such as methane and carbon dioxide to flow to the surface. Unless properly mitigated against these gases can cause significant risk to a proposed development and human health and can cause asphyxiation and explosions of the flammable gases.

Furthermore, disused coal mines can also provide a preferential pathway for contaminates at surface from both coal mining activity, other current and historical uses associated with the subject and surrounding area to migrate towards groundwater resources.

How to carry out a Coal Mining Risk Assessment

A Coal Mining Risk Assessment (CMRA) is a desk based assessment of ground stability and mining-related hazards which are posed by historical coal mining activity. A CMRA must be undertaken by a suitably academically and professionally qualified person. A CMRA should include an assessment of up-to-date third party information held by the British Geological Society and Mining Remediation Authority to understand the complex geological model beneath the subject site and the likelihood of hazards presenting a risk to any proposed development from the mining of coal.

Is a site investigation needed after a CMRA?

Following the undertaking of a desk based Coal Mining Risk Assessment it may be necessary to undertake a physical ground investigation depending on the risks associated with an individual site. The requirement of a ground investigation, the amount and the type of investigation needed will be specific to the risks associated with the proposed development.

Ground investigations can often include the investigation of shallow coal seams through the advancement of boreholes to anticipated target depths, trial pitting and probing to identify mine entries. However, in order to undertake a ground investigation that may disturb coal seams, abandoned mine workings or mine entries a ‘Coal Permit’ is legal requirement.

The permit ensures that all operations in a coal field are conducted safely and in compliance with regulations to protect the public and environment.