Coal Mining Risk Assessment: recommended geo-environmental consultants
Many regions of the UK with historic coal mining activity are at risk of ground instability, subsidence, and gas emissions due to abandoned mine workings. A Coal Mining Risk Assessment is a specialist report that evaluates the potential hazards associated with coal mining activities on or near a proposed development site. The geological information in this assessment will assist developers and planning authorities in determining whether mitigation measures are needed to ensure land safety and structural integrity.
When is a Coal Mining Risk Assessment CMRA required?
A coal mining risk assessment is often required during the planning process, especially for new developments in designated coal mining reporting areas. Common scenarios where this report may be necessary include:
1. Applications for planning consent
A local planning authority will often mandate a coal mining risk assessment before approving planning applications for new development in areas with a coal mining legacy. This ensures that potential hazards are identified and addressed before construction begins. If conditions are imposed, a well-prepared plan will ensure a rapid condition discharge.
2. Structural safety risks and ground stability concerns
Developers must consider the impact of abandoned mine entries, tunnels, and unstable ground when designing foundations and infrastructure. A coal mining risk assessment evaluates these risks and recommends appropriate engineering solutions. A developer may seek commercial advice about the development proposals and a scheme’s viability on receiving a coal mining risk assessment.
3. Environmental and public health considerations
Old mine workings are potential sources of hazardous mine gas, such as methane and carbon dioxide, which pose risks to occupants of new buildings. A coal mining risk assessment helps assess and mitigate these dangers.
4. Land transactions and due diligence
Investors and developers purchasing land in areas where there has been past coal mining activity often commission a coal mining risk assessment to determine potential liabilities before finalising transactions.
Risks posed by former mining activities
Historic coal mining operations pose several risks that must be assessed before land development. Key risks include:
1. Ground subsidence
Underground shallow coal workings can collapse over time, causing surface subsidence that may damage buildings, roads, and other infrastructure. A thorough site investigation identifies areas at risk and suggests mitigation strategies.
2. Mine shaft hazards
Abandoned mine shafts and mine entries, if not properly recorded or sealed, present a significant danger to development. Unstable shafts can cause sudden ground collapses, endangering structures and human safety.
3. Gas emissions
Disused mines often contain pockets of hazardous gases, such as methane and carbon dioxide. These gases can migrate to the surface, creating fire and explosion risks. Proper ventilation and sealing measures are crucial for safe new development.
4. Water ingress and flooding
Mining can alter groundwater movement, leading to localised flooding or unexpected water ingress into basements and excavations. A risk assessment helps determine whether additional drainage or waterproofing is required.
5. Contaminated land risks
Coal mining residues can leave behind pollutants such as heavy metals, hydrocarbons, and sulphates, which may contaminate soil and groundwater. Identifying and remediating contamination is essential for safe land use.
Who requires a Coal Mining Risk Assessment?
Several stakeholders may require a coal mining risk assessment, including:
- A local planning authority: to assess risks before granting planning consent. This will be particularly relevant in high risk areas.
- Property developers: to ensure land stability before commencing new development.
- Investors and financial institutions: to evaluate risks before financing a development project.
- Construction companies: to design and implement appropriate foundations and mitigation measures.
- Environmental regulators: regulatory information will be required to ensure compliance with safety and environmental regulations.
Conducting a Coal Mining Risk Assessment
Typically conducted by experienced geo-environmental consultants, the assessment follows a structured methodology to identify risks and recommend mitigation strategies. The process generally includes the following phases:
Phase 1: desk based assessment
The first stage desk based assessment identifies historical and geological data about the site, including:
- Reviewing Coal Authority mining reports and historical maps to identify historic coal mine workings.
- Examining geological records to assess the ground conditions and potential instability.
- Identifying known mine shafts and shallow coal workings to assess their impact on the proposed development.
- Analysing previous ground investigation reports to understand past assessments and findings.
Phase 2: site investigation
If the desk study highlights potential risks, a more detailed intrusive site investigation is carried out, which may include:
- Borehole drilling and sampling: extracting soil and rock samples to determine ground stability.
- Geotechnical testing at the site location: evaluating soil strength, compaction, and potential for subsidence.
- Gas monitoring: measuring methane, carbon dioxide, and other gases to assess explosion risks.
- Groundwater assessment: identifying potential water ingress issues related to historic coal mining activity.
Phase 3: risk evaluation and mitigation recommendations
Once data is collected and analysed, the risk assessment outlines the findings and proposes appropriate mitigation strategies, such as:
- Ground reinforcement: implementing engineered solutions like piling or grouting to stabilise the land.
- Mine shaft treatment: sealing or capping abandoned mine shafts to prevent collapse.
- Gas mitigation measures: installing gas membranes, venting systems, or soil treatment methods.
- Drainage solutions: designing drainage systems to manage groundwater effectively.
Phase 4: reporting and compliance submission
The final step is compiling the findings into a coal mining risk assessment report, which includes:
- A summary of specific coal mining risks and their implications for development proposals.
- Recommendations for mitigation measures and engineering solutions.
- Supporting documentation that enables a developer to submit a coal mining risk assessment alongside a planning application.
Comprehensive analysis of potential risks from mining issues
A coal mining risk assessment is a statutory requirement and an essential document for anyone developing land in high risk areas with a historical legacy of coal mining. It helps identify potential hazards, ensures compliance with requirements, and protects investments by providing clear recommendations for mitigating ground instability, gas emissions, and subsidence risks.
If you require a coal mining risk assessment, working with a competent person such as an experienced geo-environmental consultant, will ensure a thorough evaluation and implementation of necessary safety measures. Conducting this assessment early in the planning process helps avoid costly surprises and ensures a safe and successful development scheme.
Arbtech’s knowledgeable geo-environmental consultants carry out coal mining risk assessments across the UK. For further information, fill in the contact form at the top of this page.