The Coal Authority has announced the launch of a new report to enable consultants to carry out better subsurface characterisation to evaluate the risk from historical coal mining activity.
The Consultants Coal Mining Report names specific seams, their distance and direction to the property as well as their depth, dipping angle and the last year they were worked.
The new report is the result of a six month research and development programme carried out by the Coal Authority to understand how environmental consultants and geotechnical engineers build their own risk assessments.
It revealed that there were significant opportunities to provide more data, mapping and guidance to make the assessment process smoother. This includes automatically providing the most relevant abandoned mine catalogue reference numbers on site to make further enquiries easier.
Tailored guidance based on the results helps signpost consultants to planning and environmental professionals within the authority who can help them with specific permitting or planning submission support.
The Coal Authority has a remit to manage the coal legacy and provides standing guidance for planning authorities, developers and consultants to work in order to safeguard the landscape.
According to the authority, the long history of coal mining has left a widespread environmental legacy across some 25% of the country. This legacy includes mine shafts and shallow mine workings, which have an element of high risk but low probability of occurrence.
Nonetheless, the authority says that it deals with over 250 surface hazards resulting from the impact of mining. These are evenly split between hazards relating to mine entries and hazards relating to shallow workings, such as gas and groundwater issues.
Under the standing guidance, environmental consultants and geotechnical engineers must develop coal mine risk assessments that fully appraise the site in the context of its use and suitability, based on a detailed study of subsurface conditions.
A spokesperson for the Coal Authority said: “The challenge for consultants is that they must frequently refer to multiple sources at present to build their own ‘3D mental geology’ of the site. Assuming the development site is in a high risk area, they typically consult 1:50K Geology maps, past site investigations the freeholder may possess and obtain a standard screening report, usually the CON29M Coal Mining Search.
“The CON29M search was developed by the Coal Authority to deliver a standard set of questions and answers, approved by The Law Society that would respond to solicitors’ specific concerns about a residential or commercial property purchase.
“It does not serve the engineer or consultant well enough to develop a robust and fully informed risk assessment on behalf of their client. It is essential to understand more about the seams, outcrops, features and past investigations or actions to characterise the site better.”
The authority has said that the new Consultants Coal Mining Report is a fully enhanced desktop data report.
“Used in conjunction with retained geology Maps, consultants can gain a fuller appreciation of the seam in relation to bedrock and deposits above,” said the spokesperson. “This informs any future borehole drilling and piling estimates, identifying any risks that could affect future excavation and development.
“It also identifies the minewater treatment scheme, its management area and its interaction with seams and mine entries. This ensures that consultants can better understand how water is controlled across the site. The client will also be reassured early on that this is being controlled.
“Understanding remedial activity for other site risks such as mine gas and subsidence is also critical from a health and safety perspective. Showing hotspots of activity, especially outside the site’s immediate boundaries, helps consultants appreciate proximal risks and how they may interact with the complex subsurface geology onsite.
“Using larger mapping with more features also enables clients to get a faster, easier identification of potential issues, enhancing the visual appeal but more importantly better clarity for informed decisions.”