Checking a site against the coal mining risk data
On the coalfield a coal mining risk assessment is a validation item, and the check that triggers it takes minutes. Here is how to run it and what the report has to contain.
If a site sits in a development high risk area on the coalfield, the local validation list will almost certainly require a coal mining risk assessment with the application, and the application will be invalid without one. The check itself takes minutes. The work that follows it, which is a desk study and often intrusive investigation, takes weeks, so this is a due diligence item to run before an offer rather than after a planning consultant has drawn a layout.
Coal mining legacy reaches across the north east, Yorkshire, the east and west Midlands, Lancashire, Cumbria, the Forest of Dean, Somerset and Kent. Plenty of developers meet it for the first time at the point the council asks for the report.
Why the coalfield carries its own validation item
Past coal working leaves recorded and unrecorded features under the surface. Shallow workings can collapse. Mine entries, meaning shafts and adits, can fail decades after being capped, and many were capped to standards nobody would accept now. Mine gas migrates. Spoil tips move. None of that is picked up by a standard ground investigation aimed at foundation design, and none of it is the local planning authority's expertise.
So authorities in coalfield areas add a coal mining risk assessment to their local validation list for development in defined high risk areas, and consult the national coal mining body on applications there. That organisation was the Coal Authority and now operates as the Mining Remediation Authority, so older validation lists and standing advice still use the former name.
National policy expects the applicant to demonstrate that a site is suitable for the proposed use, taking account of ground conditions and any risks arising from land instability. The coal mining risk assessment is how that is demonstrated on the coalfield.
Finding out whether your site is affected
The regulator publishes an interactive map showing development high risk areas and the extent of the coalfield, and that map is the primary check. A site either falls within a high risk area or it does not, and the answer determines whether the report is needed. Our note on using the coalfield interactive map before you buy a site walks through the mechanics.
Three points people get wrong. A site outside the high risk area but inside the coalfield can still need consideration of mine gas or spoil. The high risk area boundary is based on recorded features, and the historic record is incomplete, particularly for workings from before the mid nineteenth century. And the boundary can be redrawn as new information comes in, so a check done three years ago for a different scheme is not a current check.
Order the mining report for the site as well. It is a commercial product from the regulator that lists recorded mine entries, seams worked, depths, dates, licensed operations, subsidence claims and any surface hazards within a defined radius. It costs a fraction of the report that will be written from it.
What the assessment has to cover
A coal mining risk assessment is a desk study with a conclusion. A competent one contains:
- The site description, proposed development and layout, with the red line shown against the coalfield data.
- The sources consulted, including the mining report, abandonment plans, historic maps, geological mapping and borehole records.
- The coal mining features identified, with distances from the site and from the proposed built form.
- An assessment of the risk each feature poses to the development, and to people.
- The further investigation proposed, with the scope of any intrusive work.
- The mitigation or remediation likely to be needed, and how it will be secured.
Point three is where the difference between a useful report and a template shows. Listing a mine entry 90 metres away with no comment is not an assessment. Stating where the entry is relative to the proposed dwellings, what its recorded depth and diameter are, and what that implies for the layout is.
Where the ground risk extends beyond stability into contamination, the work overlaps with a Land Contamination Phase 1 desk study, and it is usually more efficient to commission both together. A licensed or suitably qualified professional is legally expected for contamination work under the standards local authorities apply, and a coal mining risk assessment should equally be written by someone with geotechnical or mining competence. PlanScope can draft the structure and the policy framing, but the ground assessment itself is a specialist's document.
Mine entries and the zone of influence
A recorded shaft or adit carries a zone of influence around it, inside which building is normally avoided. The zone is calculated rather than assumed, using the shaft diameter and the depth of unconsolidated deposits above rockhead, and the regulator publishes the method. The output is a radius, and the practical effect is a no-build area that the layout has to respect.
Two consequences follow for a site with a mine entry on it. The first is layout: a zone of influence across the middle of a small site can remove the plots that made the scheme viable. The second is process: locating an entry precisely usually needs intrusive investigation, because recorded positions are frequently out by tens of metres and some entries are not recorded at all.
Any intrusive work that disturbs coal, coal measures strata or mine workings needs a permit from the regulator before it starts. Coal is vested in that body under the Coal Industry Act 1994, and drilling into it without permission is unlawful. Build the permit lead time into the programme rather than discovering it the week the rig is booked.
Investigation, remediation and what the condition will say
Where the desk study identifies credible risk, expect a condition requiring intrusive site investigation and, if necessary, remediation, to be carried out and approved before development starts. Typical remediation includes drilling and grouting shallow workings, locating and capping a mine entry to current standards, gas protection measures designed to the relevant British Standard, and long term monitoring where gas is present.
Costs vary far too widely to generalise, which is exactly why the desk study belongs in the appraisal. Grouting a hectare of shallow workings and capping two entries can be the difference between a viable site and one that is not, and no planning argument recovers it.
The consultation response from the regulator tends to be short and practical. It either raises no objection, raises no objection subject to conditions, or objects because the submitted assessment is inadequate. The third outcome is nearly always about a missing element from the list above rather than about the ground itself.
Illustrative example: a 22 unit site in a development high risk area returns two recorded shafts near the northern boundary and shallow workings at around 30 metres depth beneath the site. The desk study recommends drilling on a grid to confirm the workings, locating the shafts by trial trenching, and grouting where voids are found. The layout is revised to keep both zones of influence in open space and the parking court. Conditions secure the investigation and the remediation before work starts. Illustrative only.
Reporting it in the application
Submit the assessment as a named document, not as an appendix inside a design and access statement, because the validation officer checks for it by name. Reference it in the Planning Statement where the site suitability case is made, and state plainly that the ground risks are capable of being addressed by condition. That framing gives the case officer the sentence they need for the report.
If the site is outside a high risk area, say so explicitly in the planning statement and cite the map check and its date. Validation officers refuse applications for missing documents far more often than they query a stated reason for their absence.
This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified professional before relying on it.
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Frequently asked questions
How do I know whether my site needs a coal mining risk assessment?
Check the site on the interactive map published by the national coal mining body. If it falls within a development high risk area, the local validation list will normally require the assessment with any planning application. Record the date of the check, because boundaries are revised as new information about recorded features comes in.
What is a development high risk area?
An area defined from recorded coal mining features where legacy issues such as shallow workings, mine entries, mine gas, spoil or recorded hazards may affect surface stability and the safety of development. Sites outside these areas but within the coalfield can still raise mine gas or spoil questions, so the boundary is a trigger rather than a guarantee of safety.
What is a zone of influence around a mine entry?
A radius around a shaft or adit inside which building is normally avoided. It is calculated from the shaft diameter and the depth of unconsolidated deposits above rockhead, using the method published by the regulator. Recorded positions are often inaccurate, so locating an entry precisely usually needs trial trenching or drilling.
Do I need permission before drilling on a coalfield site?
Yes. Coal and coal mine workings are vested in the national coal mining body under the Coal Industry Act 1994, and any intrusive investigation that disturbs coal, coal measures strata or workings needs a permit from that body before it starts. Allow for the lead time when programming the site investigation.
Can the risk be dealt with by planning condition?
Usually yes. Where the desk study identifies credible risk, authorities impose conditions requiring intrusive investigation and any necessary remediation to be carried out and approved before development starts. Objections from the regulator are normally about an inadequate assessment rather than about the ground conditions themselves.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.