Wales’ disused coal tips: Who makes them safe, who pays and what happens next?
Nation.Cymru staff
Wales has nearly 2,600 monitored coal tips but with a new safety regime on the way, who will be responsible – and who will pay?
Nearly 2,600 disused coal tips are being monitored across Wales, with hundreds assessed as hav-ing the potential to affect public safety.
Most are concentrated in the south Wales Valleys, where the legacy of the coal industry remains visible decades after the closure of the mines.
But responsibility for keeping those tips safe is about to change significantly, while arguments continue over how the substantial cost of dealing with them should be divided between the Welsh and UK governments.
A new analysis by Dr Matthew Sutton of Senedd Research has examined what has changed since new legislation governing disused mine and quarry tips became law a year ago – and what happens next.
Here are some of the key questions.
How many disused tips are there?
There are almost 2,600 monitored coal tips in Wales, of which 368 are assessed as having the po-tential to affect public safety.
There may also be more than 20,000 non-coal tips across Wales, many associated with metal min-ing and quarrying.
The geographical distribution is heavily skewed towards the Valleys. Three quarters of all disused coal tips are there, along with 93% of those in the highest-risk C and D categories.
The steep landscape and concentration of communities around former mining areas mean both the likelihood of a tip failing and the potential consequences can be greater.
The danger was demonstrated most devastatingly at Aberfan in 1966, when 116 children and 28 adults were killed after a colliery spoil tip collapsed onto Pantglas Junior School and nearby homes.
More recent landslips at Tylorstown in 2020 and Cwmtillery in 2024 have underlined that the is-sue has not disappeared.
Who is responsible for them?
At present, disused tips are inspected, monitored and maintained by local authorities and Natural Resources Wales, with the UK Mining Remediation Authority also involved in work to identify, categorise and inspect them.
The Disused Mine and Quarry Tips (Wales) Act 2025 creates a new Disused Tips Authority for Wales, which will formally come into existence in April 2027.
It will maintain a register of disused tips, monitor their stability and carry out a preliminary as-sessment of every disused tip in Wales. Management plans will also be required for the highest-risk sites.
Crucially, the authority will have powers to require landowners to stabilise tips and to step in it-self where necessary.
It will be headquartered in Merthyr Tydfil and is expected to employ up to 77 staff.
Who pays?
The question of who should meet the cost remains politically contentious.
Plaid Cymru’s 2026 manifesto committed to a national tip remediation programme which it said should be funded “properly and in full” by the UK Government.
The argument centres on the fact that environmental protection is devolved but the overwhelming majority of Wales’ coal mines closed before devolution.
First Minister Rhun ap Iorwerth set out the Welsh Government’s position in the Senedd in June.
He said: “The mining industry, of course, predates devolution, so we’re clearly of the view that it’s the UK Government that should foot that bill, and we’ll make the case for that.”
The scale of the potential bill has been the subject of debate.
In 2021, the Welsh Government estimated that coal tip remediation could cost at least £600m over 15 years. However, the then Deputy First Minister said earlier this year that the figure had been an initial estimate and was not based on detailed information about exactly which schemes would be required.
The UK Government provided £25m towards Welsh coal tip remediation in 2025-26 and has committed further funding equivalent to £39.3m a year between 2026 and 2029.
The Welsh Government has also funded work through its Coal Tip Safety Grant.
A multi-year scheme announced in January will allocate £81.6m to Natural Resources Wales and ten councils between 2026 and 2029, allowing larger and more complicated projects to be under-taken over several financial years.
What difference will climate change make?
Welsh winters are becoming wetter and more frequent intense storms increase the danger of land-slides.
The independent Climate Change Committee has identified disused tips as an “urgent present-day climate risk” and singled out south Wales as the highest-risk part of the UK.
It has warned that increased rainfall and storms will increase both the potential for mining tip landslides and the number of sites requiring adaptation.
The committee has proposed a UK-wide target for the most dangerous tips to be assessed and adapted by 2035, drawing on the approach already being taken in Wales.
Managing those changing risks will become one of the responsibilities of the new Disused Tips Authority.
Can old tips have a new use?
Making disused tips safe comes at considerable cost, but remediation can also create opportunities in communities which were once dependent on the industries that created them.
The legislation’s explanatory memorandum identified potential economic benefits including jobs in remediation, avoiding the future costs of landslides and improving community wellbeing. Around 60 new jobs are also expected to be created through the establishment of the new authori-ty.
There are already examples of former industrial sites being transformed.
At Parc Penallta in Ystrad Mynach, former coal tips have become biodiverse habitats and recrea-tional space, including the 200-metre-long Sultan the Pit Pony earthwork.
Other parts of Wales’ mining legacy could have a role in renewable energy, with abandoned mines potentially used for mine-water heat networks and methane capture.
More than half a century after Aberfan, the safety of Wales’ disused tips remains a major and cost-ly challenge.
With a new authority taking responsibility from next year and climate change increasing the risks, arguments over who should pay for the work are likely to continue.
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