Documents for a site in a coalfield referral area

If your site falls inside a coalfield development referral area, the council will in nearly every case require a coal mining risk assessment as a local validation item, and the Coal Authority becomes a consultee on the application. The coal mining risk assessment documents expected are a desk study of mining records, a risk appraisal, and where risk is identified, a programme of intrusive investigation with a remediation and verification strategy. Layout is the thing to get right first, because mine entries and their zones of influence take land out of use and no foundation design makes that go away.

What a referral area means in practice

Coalfield referral areas, often described as development high risk areas, are mapped zones where recorded or probable mining features sit close enough to the surface to affect development. They cover a surprising amount of the Midlands, the North East, Yorkshire, Lancashire, the North West, Kent and parts of Somerset and Gloucestershire.

Being inside one does not mean your site is undevelopable. It means three things. The council's validation checklist will require a risk assessment with the application, the Coal Authority will be consulted and may object until the risk is understood, and any work that disturbs coal or enters workings needs a separate permission from the Coal Authority under the Coal Industry Act 1994, which is nothing to do with your planning permission.

Check the position before you buy. The mapping is public and a desk check costs very little compared with discovering a recorded shaft under the middle of your proposed terrace.

The mining risk assessment and its sources

A credible risk assessment is a piece of research, not a template. It should name its sources and reproduce the relevant extracts.

• The Coal Authority's mining records: abandoned mine plans, shaft and adit records, and any records of past treatment or grouting.
• Geological mapping and borehole records from the British Geological Survey, to establish the seam sequence, dip and rockhead depth.
• Historic Ordnance Survey mapping across several editions, to pick up surface features such as spoil heaps, tramways, air shafts and capped entries that the mine plans miss.
• A site walkover looking for depressions, differential settlement in existing structures, and vegetation patterns over backfilled features.
• Records of unrecorded or probable workings in the area, which are common where mining predates systematic record keeping.

The output should be a plan showing every identified feature with its confidence level, a conclusion on whether intrusive investigation is needed, and if so, where. Councils reject assessments that stop at "no recorded features" without addressing probable shallow workings.

Shallow workings and treatment options

Shallow workings are the most frequent finding. Pillar and stall extraction left voids and partially collapsed ground within a few metres of the surface in many areas, and the residual risk is differential settlement or a sudden collapse under load.

Treatment usually means one of three approaches. Drilling and grouting fills voids and consolidates broken ground across the footprint, which is the standard solution and is priced by the metre of drilling. Excavation and replacement works where the workings are very shallow and the site can take the muck away economically. Foundation design that bridges or bypasses the problem, using a reinforced raft or piles taken to competent strata below the workings, is the third, and it tends to be chosen where the void depth is well established.

The decision is a geotechnical one and belongs in a Geotechnical Assessment prepared by a suitably qualified engineer, with professional review strongly advised. What matters at planning stage is that the layout does not assume a solution that site investigation later rules out.

Mine entries and stand-off distances

A recorded or suspected mine entry is the hard constraint. Shafts and adits have a zone of influence around them within which building is not acceptable, because the collar can fail and because the shaft lining and backfill degrade.

There is no single national stand-off figure. The distance is calculated from the shaft diameter, its depth, the ground conditions and the state of any treatment, using the Coal Authority's guidance on development near mine entries as the starting point and confirmed by investigation. In practice the entry has to be located precisely on the ground, which means probing or trial trenching rather than relying on a plan position that may be tens of metres out.

So treat a possible entry as a design input at the earliest stage. Put it in open space, a parking court or a drainage feature, and plan the layout around it. A scheme that has to be redrawn after the entry is found during site investigation loses months, and if the permission has already been granted, a section 73 application follows.

Gas risk and ventilation measures

Mine gas is the second risk and it is often underestimated. Methane and carbon dioxide migrate along workings, fissures and old shafts, and carbon monoxide can be present where spontaneous combustion has occurred in spoil.

Assessment follows the standard ground gas route: a conceptual model of sources, pathways and receptors, then monitoring over a period long enough to capture falling atmospheric pressure, which is when emissions peak. The industry guidance on ground gas and the British Standard on gas protection for buildings set the characteristic situation and the corresponding protection measures, which range from a ventilated subfloor void and a gas-resistant membrane to active ventilation in severe cases.

Gas and contamination are usually dealt with in the same document set. Where spoil, former colliery buildings or made ground are present, the contaminated land assessment covers both, and the NPPF places responsibility on the developer with reports expected to be prepared in accordance with BS 10175 by suitably qualified and experienced persons. For land contamination work a competent professional is legally required rather than merely advisable, and an AI-assisted draft is a starting point for that professional rather than a substitute.

Groundwater can complicate matters further where mine water is rising. If the site also sits in a groundwater source protection zone, the two constraints interact, and the document set for a scheme in a source protection zone overlaps with this one.

Conditions that commonly follow

Expect three conditions and plan the programme around them.

First, a condition requiring intrusive site investigation and a remediation scheme to be submitted and approved before any development begins. This is the condition that catches developers who assumed the desk study was enough, because the investigation itself needs a Coal Authority permit where it will disturb coal, and that permit takes time.

Second, a condition requiring the approved remediation to be carried out and a verification report submitted before occupation. Grouting records, as-built drilling plans and gas monitoring results all form part of verification, so the ground worker needs to know at the outset what records to keep.

Third, a condition dealing with unexpected contamination or features found during construction, requiring work to stop and a revised scheme to be agreed.

The document set that goes in with the application is therefore short: the coal mining risk assessment, a phase 1 desk study covering contamination and gas, a layout plan showing any entries and their stand-off, and a statement explaining how the layout responds to the findings. Intrusive work can follow under condition, but only if the layout is credible without it.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. Browse the PlanScope report types to see which reports a coalfield site typically needs. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.