Planning reports for a site in a coal mining high risk area

If your site sits in a Development High Risk Area, a coal mining risk assessment is expected with the planning application, and an application submitted without one is likely to be held up at validation or met with a holding objection. The areas are defined nationally by the Coal Authority, the body established under the Coal Industry Act 1994 and now operating under the name Mining Remediation Authority, and they cover a surprising amount of the Midlands, the North, South Wales, Kent and parts of Scotland. The check takes minutes. The consequences of skipping it run to foundation redesign and a permit you did not know you needed.

Checking whether the site is in a referral area

Start with the Authority's own interactive map, which shows the Development High Risk Area boundaries. If the site falls inside, the standing advice applies and a risk assessment is needed. If it falls in a low risk area, no assessment is normally required, though you should still record the check.

Then buy a mining report for the site. A commercial report for a conveyance is not the same product as the information a consultant needs, so tell the supplier it is for a development risk assessment. What you want is the record of mine entries, recorded workings by seam and depth, past and future underground and surface mining, mine gas, mine water treatment and any coal mining subsidence claim history.

Note the distinction between a high risk area, where the assessment is required at application stage, and the wider reporting area where mining legacy may still exist but the national trigger does not bite. Our note on documents for a scheme in a coal mining reporting area covers the second case.

What the risk assessment covers

A coal mining risk assessment is a desk study with a conclusion. It is not a ground investigation, and it is not a geotechnical design.

The content a consultee expects runs roughly in this order: the site setting and the proposed development, the sources consulted, the recorded coal seams and their depth below the site, the presence and position of mine entries including shafts and adits, recorded and probable unrecorded shallow workings, the outcrop position of any seam, mine gas and mine water, surface hazards such as spoil and former colliery infrastructure, an assessment of the risk each poses to the proposal, and the further work recommended.

The last section is the one planning officers read. A report that identifies shallow workings and then recommends intrusive investigation, with the results to be addressed by condition, is a report that lets a decision be made. A report that lists the sources and concludes that risks are "unlikely to be significant" without reasoning is not.

Mine entries, shafts and standoff distances

Mine entries are the hazard that changes layouts. A recorded shaft has a position accuracy that depends on the quality of the abandonment plan, and an unrecorded shaft may be anywhere on a site with old workings beneath it.

The usual approach is a zone of influence around the entry, within which no building is permitted and often no hard surfacing either, sized from the shaft's depth, diameter, likely backfill condition and the accuracy of its recorded position. That zone is established by the consultant and agreed with the consultee rather than read off a table, so expect it to be site specific.

Where a shaft sits in the middle of a developable parcel, the practical options are to locate it precisely by trial trenching or geophysics, to treat and cap it to a design accepted by the Authority, or to design around it as open space. Treatment needs the Authority's permission because it involves working on or near its property.

Permits to enter or disturb coal

This is the requirement self-builders most often miss. Any activity that will enter, disturb or come into contact with coal or Authority property needs the Authority's prior written permission, and that includes a good deal of routine work.

• Boreholes and probe drilling to investigate shallow workings.
• Grouting or drilling and consolidation of workings.
• Piling that passes through or near a seam.
• Deep excavation, basements and attenuation structures that reach coal.
• Investigation or treatment of a mine entry.

Permission takes time and is refused where the proposal is inadequate, so build it into the programme alongside the ground investigation. Starting drilling without it is a breach, and your contractor's insurer will care about that even if nobody else notices.

Foundation design and what it costs you

Risk translates into engineering, and the engineering is where the money sits. The common outcomes, roughly in order of frequency:

Gas monitoring deserves its own warning. A credible gas risk assessment needs readings across a range of atmospheric pressures, which cannot be compressed into a fortnight. If mine gas is flagged, start monitoring early, because no amount of money buys back the time.

Where the site also carries colliery spoil, former washeries or made ground, the contamination and geotechnical workstreams overlap and are best commissioned together. The scope of each is set out on the Geotechnical Assessment and contaminated land assessment pages.

Who the consultee is and what it asks for

The Authority is consulted on applications affecting land in Development High Risk Areas and publishes standing advice setting out what it expects. Its responses follow a pattern.

Where the risk assessment is adequate and recommends further work, it will usually raise no objection subject to conditions requiring intrusive site investigation and, where necessary, a scheme of remedial works, each approved before work starts on site. Where no assessment has been submitted, it will object until one is provided. Where the assessment is inadequate, it will say which element is missing, and the application sits until that is fixed.

Councils in former mining areas also carry local validation requirements, so check the authority's own list as well as the national position. The full set of supporting documents by category is on the planning report index.

The document set to submit

For a single dwelling or small scheme in a high risk area, the pack usually looks like this.

1. A coal mining risk assessment, prepared by a suitably qualified and experienced consultant, with the mining report appended.
2. Where shallow workings or a mine entry are identified, a proposal for intrusive investigation, either submitted with the application or secured by condition.
3. A geotechnical and ground conditions assessment where foundations are affected.
4. A contamination desk study where spoil, made ground or former industrial use is present.
5. A gas risk assessment where mine gas is identified as a potential issue, with the monitoring programme stated.
6. The standard application documents, with the mining constraints shown on the site layout rather than mentioned only in text.

Two documents on that list need a named professional. A coal mining risk assessment is prepared by a consultant with relevant experience, and PlanScope does not produce that report type. What PlanScope can draft is the surrounding material, including the geotechnical and contamination documents in its own library, which then go to a suitably qualified professional for review and sign-off.

Enter your postcode on PlanScope to see which of the 66 report types a site in a former mining area is likely to need before you instruct anyone.

This is general guidance, not legal advice. Mining legacy is site specific and the requirements differ between authorities, so check the position with your local planning authority, the Authority's standing advice and a qualified ground engineering professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.