Coal referral areas and the coal mining risk assessment

If your site falls within a development high risk area in the English coalfields, the local planning authority will consult the mining authority and will expect a coal mining risk assessment submitted with the application. Leaving it to a condition is not usually an option, because the assessment may change the foundation design, the layout or the viability of the plot.

The regulator here is the body long known as the Coal Authority, renamed the Mining Remediation Authority in 2024. Older documents, validation checklists and consultation responses still use the former name, and both refer to the same organisation and the same datasets.

What a development high risk area means

The high risk area is a mapped zone covering land where recorded or probable coal mining features could affect surface development. The features that put land into it are mine entries such as shafts and adits, recorded shallow workings, probable unrecorded shallow workings, mine gas, spoil heaps and surface hazards such as areas of past opencast working.

Falling inside the zone does not mean the site is unbuildable. Most sites in the coalfields are developed successfully. It means the risk has to be assessed and, where present, treated, and the council will not validate an application in the zone without the assessment.

Outside the high risk area, sites in a coalfield still attract a lower level of interest. A standard mining report may be recommended, and where a mine entry lies just beyond the boundary the authority may still comment.

Checking whether your site is affected

Start with the authority's published interactive mapping, which shows the high risk area boundaries and can be interrogated by address. The council's own constraints layer usually replicates it and sometimes lags behind.

Do not confuse the conveyancing mining report with the planning document. A mining report ordered during a purchase tells you what is recorded beneath the property and is a search product. A coal mining risk assessment is an interpretive report prepared by a competent person that assesses the risk to the proposed development and recommends what to do about it.

Where the site also has an industrial history, the coal work overlaps with the contamination desk study, and the records that show up are discussed in contaminated land registers and what a search shows.

What a coal mining risk assessment contains

The structure is consistent across the industry, and councils reject reports that skip the interpretation and simply attach the data.

• A review of the coal mining data for the site and a surrounding buffer, including seam names, depths, recorded workings and dates.
• Identification of mine entries within and adjoining the site, with their recorded positions and any treatment history.
• An assessment of the potential for unrecorded shallow workings based on seam depth, dip and the historic working methods of the district.
• Consideration of mine gas and of any groundwater or minewater issues.
• An assessment of the risk each feature presents to the specific proposal, taking account of foundation depth and layout.
• Recommendations for further investigation or mitigation, and how they should be secured.

That fifth point is where weak reports fail. A generic statement that shallow workings may be present, with no link to the proposed foundation depth or the position of the plots, will draw a holding objection.

Buffer sizes vary with the authority's advice, but the data review should extend well beyond the red line, because a shaft on the neighbouring plot can still place part of your site inside its zone of influence.

Shafts, adits and shallow workings

Mine entries are the feature that changes a layout. A recorded shaft carries a zone of influence around it within which building is not acceptable, and the extent of that zone is calculated from the shaft diameter and the depth of superficial deposits to rockhead rather than taken from a standard table. Recorded positions are also often approximate, which is why locating a shaft on the ground is usually one of the first site tasks.

Shallow workings are treated differently. Where seams outcrop or lie within a few tens of metres of the surface, historic pillar and stall working may have left voids that can migrate upwards. The usual response is a grid of rotary open hole probeholes drilled to competent strata beneath the workings, followed by drilling and grouting where voids are proved.

Adits, drift entries and unrecorded bell pits in the outcrop zone are harder again, because the records are poorest exactly where the working was oldest.

Intrusive investigation and the permit

Intrusive works that enter or disturb coal, mine workings or a mine entry need a permit from the authority before they start. That applies to site investigation boreholes and to any grouting or capping works, and it is a separate approval from planning permission and from building control.

Allow time for it. The permit application asks for the proposed locations, the drilling method, the grouting specification and details of the contractor, and it is not granted instantly. Coordinating the coal permit with the ground investigation for contamination and geotechnical design in a single round of drilling saves a mobilisation, and the geotechnical output feeds straight into a Geotechnical Assessment for the foundation design.

Where ground gas is a concern, the investigation should be designed to gather gas monitoring data over a suitable period and range of atmospheric conditions, which is a matter of months rather than a single visit. The contamination stream runs alongside it and is reported in a contaminated land assessment.

Mine gas deserves its own paragraph. Methane and carbon dioxide can migrate from workings through fissures and made ground, and the assessment should say whether gas protection measures are likely to be needed and to what characteristic situation. Designing the gas protection into the floor slab early is far cheaper than retrofitting a membrane after the raft is poured.

How the condition is worded

Where the assessment shows risk that can be dealt with, the authority usually recommends a condition rather than an objection. The standard sequence is a pre-commencement condition requiring intrusive site investigation and, where necessary, a remediation scheme, approval of that scheme, implementation, and submission of a verification report before occupation.

Read the condition carefully before accepting it. A condition requiring investigation before any development starts on site will catch demolition and site clearance, and a scheme that needs the site cleared before rigs can get on will need the wording adjusted at the drafting stage rather than by a later application.

Other buried constraints are handled through comparable consultation routes, and the approach taken by infrastructure owners is set out in Network Rail asset protection in planning.

A note on who prepares it

Councils expect the assessment to be prepared by someone with relevant experience in mining geology or geotechnical engineering, and professional review is strongly advised before submission. Ground risk is one area where an unqualified report costs more than it saves, because the consultee response is a holding objection and the application stalls until it is answered.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified 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.