Coalfield referral areas and what the report must cover

If your site sits in a Coal Authority referral area, the local planning authority will expect a coal mining risk assessment with the application, and without one the application may not be validated. The referral areas, published as Development High Risk Areas, cover the parts of the coalfield where recorded mining legacy could affect development or be affected by it. The high risk areas are a subset of the coalfield as a whole, concentrated where shallow workings and mine entries are recorded.

What a development high risk area means

The national coal mining body, the Coal Authority, which now operates as the Mining Remediation Authority, divides the coalfield into two. A Development High Risk Area, where recorded coal mining features could present a risk to development, and a low risk area, where standing advice applies and no bespoke report is normally sought.

High risk status is triggered by recorded features rather than by geology alone. Mine entries such as shafts and adits, recorded shallow coal workings, areas of past ground movement, mine gas records, and surface hazards including spoil and mine water discharges all put land into the category.

Being in a high risk area is not a constraint in the way that a designation is. Development in these areas happens all the time, and it happens with an evidence base and, where needed, remediation. What it does mean is that the report is not optional and the layout may change.

Checking whether your site is in one

Three checks, in this order.

Start with the coal mining body's own interactive map viewer, which shows the referral area boundaries and recorded features. Take a dated extract and record the coordinates you queried. Then obtain a coal mining report for the site, which returns the recorded information held for that specific parcel, including mine entries within a defined distance of the boundary.

Second, look at the authority's own constraint layer and validation checklist. Coalfield authorities list the coal mining risk assessment explicitly among their local validation requirements, and some set their own thresholds for when it is needed.

Third, look at the geology and the history independently. British Geological Survey mapping, historical Ordnance Survey editions and any previous site investigation reports often reveal features that never made it into the abandonment plans, particularly from workings that predate the record keeping. Early bell pits and unrecorded shallow workings are the classic case, and the absence of a record is not evidence of absence.

What the coal mining risk assessment has to cover

A report that gets past the consultee response does six things:

1. A desk study of the mining records, including abandonment plans, seam names, depths and thicknesses, and the dates of working
2. Identification of mine entries within the site and within a defined distance of the boundary, with their recorded positions and an honest statement of the accuracy of those positions
3. An assessment of shallow workings, including the depth of cover above the workings and whether they are likely to have collapsed or remain open
4. Mine gas, mine water and surface hazard considerations, including spoil, past subsidence damage claims and any recorded discharges
5. A conclusion on whether the recorded legacy presents a risk to the proposed development, and whether the development would affect the legacy
6. Recommendations, which on most high risk sites means intrusive investigation, and a statement of what form it should take

The last point is where thin reports fail. A report that recites the records and concludes that further investigation may be required tells the consultee nothing. Say what investigation, on what grid, to what depth, and what will be done with the results.

This is specialist geotechnical work. A coal mining risk assessment is prepared by a suitably qualified engineering geologist or geotechnical engineer and is not one of the report types PlanScope generates. The surrounding ground conditions narrative can sit in a Geotechnical Assessment, and the separate contamination questions raised by spoil and mine water belong in a contaminated land assessment.

Shafts, adits and shallow workings

Mine entry positions in abandonment plans carry real uncertainty. A shaft plotted from a nineteenth century survey may be tens of metres from where it actually is, which is why locating it on site, by probe drilling or geophysics, is part of the investigation rather than an optional extra.

Once located, a mine entry needs a zone around it kept clear of development. The zone is calculated from the shaft diameter and the depth of unconsolidated deposits at the surface, on the basis that the ground can migrate into the shaft if the cap fails, and it is usually laid out as open space, highway or parking rather than built on. Treating and capping a shaft to a modern standard is possible and is expensive, and it does not remove the need for a standoff.

Shallow workings are the more common problem. Where coal has been worked at shallow depth, the void may have collapsed and consolidated, or it may not, and the difference is established by drilling. Rotary open hole probe drilling on a grid across the development footprint is the usual method, with the grid spacing set by the seam geometry and the sensitivity of the proposed structures.

Mine gas deserves separate attention. Methane and carbon dioxide can migrate along workings and up old shafts, and where monitoring shows a risk, gas protection measures designed to the recognised standards are built into the floor construction. That is the same discipline as other ground gas work, and the way a requirement crystallises is similar to radon protection and where the requirement bites.

Remediation, and what it does to the layout

Remediation for shallow workings is normally drilling and grouting, filling the void and any broken ground above it with a cementitious grout on a designed pattern. Costs scale with area and depth, so it is a real line in an appraisal rather than a contingency.

The alternative is foundation design: piles or a piled raft founded below the workings, or a reinforced raft designed to span a potential void. Each has consequences. Piling into or through workings needs care and a permit, and it raises the question of whether piling will breach a competent stratum and create a new pathway for gas or water.

Layout is affected in three ways. Mine entry standoffs remove developable area. Grouting zones cost less to deliver under roads and gardens than under buildings, which argues for arranging built form away from the worst areas. And gas protection measures constrain floor build-ups, service penetrations and ventilated void details, which the architect needs to know before the plans are fixed rather than after.

Permits to enter or disturb coal

Coal and mine workings are vested in the coal mining body, so disturbing them needs its permission. A permit is required for activities that will enter or disturb coal or mine workings, and that includes site investigation drilling that intersects a seam, grouting operations, and piling that enters workings. Dewatering that affects mine water is a further consideration and can require its own consent, in the same way that dewatering a basement can need a permit.

Apply early. Permits are routine and they are not instant, and a contractor standing idle waiting for one is an avoidable cost. Build the permit into the programme alongside the investigation, not after it.

Submitting it with the application

Include the coal mining risk assessment in the submission rather than offering it by condition. Coalfield authorities consult the coal mining body, which responds with a comment on the adequacy of the assessment, and a submission without one usually produces a holding objection.

Where intrusive investigation has not been completed before submission, the report should still conclude on what is needed, and the authority will normally condition the investigation, the remediation scheme and a verification report. That is a workable outcome. What is not workable is a report that leaves the consultee unable to say whether the site can be developed at all, because that is the comment that turns into a recommendation for refusal.

One honest uncertainty. Records improve, and features are found during construction on sites whose desk study showed nothing. Carry a contingency and a watching brief on any coalfield site, whatever the report says.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it, and take referral area boundaries and permit requirements from the current published sources. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.

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