Significant risk posed by waste from UK's largest opencast mine

Serious worries have emerged regarding the stability of three massive spoil heaps left above Merthyr Tydfil after the closure of the UKs final open-cast coal mine. A geotechnical assessment commissioned by the local council highlighted a significant risk of slope instability at the Ffos-y-Fran site, while campaigners described plans to leave the tips intact as staggering.

Correspondence obtained by the BBC indicates the Welsh government is considering stepping in to oversee the final planning decision. Mining company Merthyr South Wales Ltd (MSW) has rejected claims that its engineered tips pose risks similar to older coal waste heaps, calling such comparisons incorrect and misleading.

The three overburden mounds, OB1, OB2, and OB3, hold roughly 37 million cubic metres of material excavated during mining. Despite mining halting two years ago, uncertainty continues over the future of the controversial project. Approved in 2005, Ffos-y-Fran was classified as a land reclamation scheme, requiring part of the profits from selling 11 million tonnes of coal over 15 years to restore the site to green hillside for public use.

Local resident Chris Austin expressed frustration, noting the community expected a site suitable for agriculture and recreation but now faces a dangerous void, dangerous tips, and areas we can't use. His wife Alyson added that the situation was extremely worrying. Residents feel the community has endured years of disruption without guaranteed restoration.

MSW, which continued coal extraction beyond its original permit, has submitted a revised, less costly restoration plan citing limited funds. Originally, spoil tips were to fill the 175m-deep mining void. The company now plans to lower one tip while leaving the other two intact, describing them as long-term stable and suggesting the pit could become a natural lake.

Merthyr Tydfil council commissioned WSP engineering to assess the tips. The report concluded the structures were temporary earthworks and raised concerns about long-term stability and potential risks to residents. Climate change impacts, it noted, were largely unaccounted for. One tip, OB1, which rises 170m above a main road, experienced a landslide in 2022, and WSP highlighted similar failures in South Wales after heavy rainfall.

Plaid Cymrus climate spokesperson, Delyth Jewell, warned of a botched restoration, calling it staggering and unconscionable to leave the tips in place. The newly established Disused Tips Authority for Wales may now need to monitor the Ffos-y-Fran mounds, adding to public responsibilities.

MSW challenged WSPs findings, commissioning James Associates, which argued the tips were engineered to approved standards and monitored. They claimed the OB1 landslide resulted from excavation and could be mitigated with proper engineering, while noting differences from historical colliery tips in terms of slope and drainage.

The company also claims the new plan is more sustainable, reducing emissions and machinery use, while promoting biodiversity. Cost estimates for full restoration range from 50m to 175m, with MSW currently preparing detailed figures. A 15m joint fund with the council may act as a financial safety net if required.

Campaigners criticized oversight of the mine as epic mismanagement that risks leaving a permanent scar over Merthyr Tydfil. Emails show the Welsh government is weighing intervention options, mindful of potential consequences like site abandonment. Jewell emphasized a moral obligation to protect residents safety.

MSW responded, expressing disappointment at political pressure, emphasizing confidence in a lawful, evidence-based planning process. The council plans further consultation once it receives additional information, while the Welsh government continues to review the case, working with partners to secure the best outcome for local communities.

Analysis: Risks and Responsibilities at Ffos-y-Fran

The recent geotechnical assessment of the Ffos-y-Fran spoil tips raises urgent questions about long-term safety and accountability. Despite assurances from Merthyr South Wales Ltd (MSW) that the engineered tips are stable, the WSP report identifies significant risks of slope failure, particularly in the context of climate change and heavy rainfall. OB1’s 2022 landslide underscores that even engineered structures can fail under certain conditions.

Community concerns are substantial. Residents expected a site restored for recreation and agriculture but now face potentially hazardous mounds and an uncertain landscape. The revised restoration plan from MSW reduces costs but leaves two tips intact, intensifying worries over public safety and environmental responsibility.

Policy and oversight gaps are evident. The Welsh government may need to intervene, while the newly formed Disused Tips Authority for Wales could assume monitoring duties. The situation highlights the tension between private cost-cutting, engineering assurances, and the public’s expectation of a safe, restored landscape. Effective, transparent oversight will be critical to prevent long-term risks to Merthyr Tydfil residents.

Sources:

• Waste from UK's largest opencast mine 'poses significant risk'