A landslide in Cwmtillery in Blaenau Gwent brought chilling reminders of past disaster when it was revealed that it was caused by a former coal tip. Some 40 homes were evacuated and roads left covered in mud, boulders and sludge during some of the heaviest rainfall recorded during Storm Bert on the night of 24th November last year.
An issue of water developed due to strong percolation from locally heavy storm rainfall. This saturated the structure of the edge of the coal tip, causing this (but not the main part of the tip) to slip, entering properties and damaging infrastructure.
Contractors attended the site after the evacuation, quickly identifying the water source and diverting it to an offsite drainage system.
No clear risk classification
The incident highlighted the fragility of the soil systems from the made ground of the spoil tips that are very often located adjacent and above former coal mining towns and villages like Cwmtillery.
Back in 2020, another incident above Tylorstown in Rhondda Fach after extreme rainfall following Storm Dennis, pressed home the fact that many tips were in a precarious state of maintenance. Thousands of tonnes of rock and debris slid down the side of the valley from the Llanwonno tip, while other slips took place on the railway line to Aberdare near Mountain Ash, and in Wattstown and Pontygwaith.
What was also clear was that there was no one central record of how former coal tips were classified according to their degree of risk.
Wave of Inspections leads to change
Since the Tylorstown slip, the Welsh Government has been working with the Coal Authority, councils and Natural Resources Wales to identify all disused coal tips across Wales. There have been 1,400 inspections carried out and further inspections by the Coal Authority and Natural Resources Wales.
This has identified a total of 2,573 disused coal tips – the majority are classified as R, A or B and have the least risk – and they are identified here. The remaining 360 are categorised as C and D and deemed highest risk, requiring regular inspection. They are identified here.
There are two coal tips directly above Cwmtillery, one of which is Category D, therefore the most dangerous and least stable. It is described as a tip with the potential to impact public safety and has to be inspected at least twice a year.
New Disused Tips Authority Proposed
Following the classification work, coincidental to the recent landslip but underlining its importance, a new authority for tackling dangerous abandoned coal tips has been proposed by the Welsh government in an effort to prevent future disasters.
The Disused Tips Authority for Wales would be established under legislation introduced in December 2024 by the Deputy First Minister, Huw Irranca-Davies.
The Authority would take responsibility for the assessment, registration, monitoring and management of disused tips. The Welsh Government has also asked the Law Commission to evaluate existing legislation on this and their report concluded that the current law does not offer an effective framework and reform was recommended.
Plaid Cymru has called for the UK government to pay the full £600m estimated cost of remediating coal tips over the next decade to protect communities and prevent future disasters. The UK government announced £25m to tackle the issue in the most recent budget.
Plaid Cymru’s spokesperson for climate change, Delyth Jewell, said: “The disused mine and quarry tips (Wales) bill is an important step towards addressing the urgent safety risks posed by Wales’ disused coal tips.
“But legislation alone is not enough. With hundreds of high-risk tips and thousands more across the country, we cannot underestimate the urgency of the need to secure the full £600m from Westminster to remediate coal tips in Wales and prevent future disasters.
“Given the increasingly extreme weather we are experiencing, there is a heightened risk of landslides and tip instability.”
Identifying Mining Legacy Risk
Our long industrial mining legacy stretches across all corners of the country – whether coal, tin, chalk or any of over 50 minerals mined. While some traces of past mining activity remain unseen and largely forgotten, waiting to be revealed by our changing climate, some are more obvious. Coal spoil tips loom over many communities and the narrow steep valleys of South Wales are among some of the most vulnerable to subsurface and run off flooding, as we have seen with recent storms.
Recognising the complex inter-relationship between former mine workings, made ground from spoil heaps and water systems is one of the many areas of expertise by our mining geology team.
Alongside our CON29M, GeoRisk reports, Avista and commercial reports, our geology consultants are on hand to advise you and your client where past mining risks could present an issue to the property or site during a transaction. For more information, visit www.groundsure.com/mining-risk-assessment/, email info@groundsure.com or call us on 01273 257755.
References
https://www.gov.wales/disused-mine-and-quarry-tips-wales-bill
https://www.blaenau-gwent.gov.uk/en/news/cwmtillery-landslide-update
https://datamap.gov.wales/maps/category-r-a-and-b-disused-coal-tips-in-wales