The oversight of what was once Britain’s largest open-cast coal mine has been described as a case of “epic mismanagement” with “heartbreaking” consequences for local communities.

A Senedd committee warned of a “permanent scar” above Merthyr Tydfil if the huge Ffos-y-Fran site was not fully restored.

The report contains sharp criticism of the mine operator and says that the Welsh Government and other authorities had ignored previous warnings about the future of the mine site.

The Welsh Government said it would take the committee’s recommendations into account.

Mining company Merthyr (South Wales) Limited said it recently held a “constructive” meeting with all relevant public authorities and another is planned for the end of September.

It said progress was continuing in developing a revised restoration proposal for the site.

According to the Senedd’s Climate Change, Environment and Infrastructure Committee, the Ffos-y-Fran saga is the latest in a long list of “broken promises” regarding the restoration of opencast mines in Wales.

“Hearing from local residents about the impact these sites have had … was the most heartbreaking aspect of Our requestsaid a report.

“People’s lives, health, well-being and homes have been severely impacted for many years, if not decades.”

Ffos-y-Fran, which closed in November 2023, was a “symbol of the failure of the system,” it said.

The mine operator had sparked anger and legal action from activists after to continue coal mining and coal sales beyond one year after the expiry of the building permit period.

The company is now working on a different – ​​and far more cost-effective – redevelopment plan for the site, after previously warning that there were “insufficient funds” to implement the original agreement.

Alyson and Chris Austin live near the open-cast mine, which is about the size of 400 football fields, and testified before the investigative committee.

“We are very concerned about what the future holds for Ffos-y-Fran,” they said.

“The mining company should keep its promise of full restoration and the council should not let them get away with leaving us with dangerous and abandoned land.”

The couple said they felt they had been let down by the local authority, the Welsh Government and government agencies at all levels.

A complete clean-up of the site could cost up to £120 million. This would involve pushing three huge spoil heaps back into the opencast mine and turning the area back into a green hill for the local population.

However, the Committee heard that an approach currently being considered would involve leaving a ‘water body’ within the mining void.

Residents described the proposal as a potentially “dangerous” and “contaminated” Lake.

The mining company wants to tap into a £15 million bank account jointly managed by the council, which will be used to protect some of the company’s cash for recovery.

“Like so many others, (the company) has made a profit from the site, but now the money they promised for restoration is not there,” the committee said.

The investigation revealed that the company had paid almost £50 million in dividends and royalties from the business since 2017.

The report states that the local authority now has “no choice but to accept the site operator’s offer”.

The “unacceptable result” follows a pattern that has also been seen at other open-cast mining sites, where the municipalities were “held in the hand” and had to reckon with enormous costs if the companies ultimately decided to withdraw.

However, criticism was also directed at Merthyr Tydfil Council, the Welsh Government and other authorities involved in overseeing the mine for almost twenty years.

A report commissioned by the Welsh Government in 2014 contained “significant and clear warnings of potential problems at Ffos-y-Fran” due to “inadequate bond coverage,” the committee said.

And the UK Coal Authority’s “Best Practice Guidance” in 2016 called for the remediation obligations for opencast mining sites to be reassessed annually.

“We have to ask ourselves whether the local authority and the Welsh Government have taken all the necessary steps to achieve a better outcome for the local community,” the committee said.

It calls for tougher measures for breaches of planning regulations and greater involvement of local residents in decisions on mining sites. Among other things, it calls for the community to have some degree of ownership of all future projects.

Although climate change laws make it unlikely that new opencast mines will be approved in Wales, the committee warned that remediation of old coal dumps could lead to similar problems, particularly if companies want to mine and sell coal to fund efforts to secure the sites.

Committee chairman Llyr Gruffydd MS said residents of opencast mines too often felt “completely let down by the authorities who are supposed to protect them”.

In Ffos-y-Fran, time is “fast running out to secure what was promised to the local community,” he said, calling on all those involved to “learn from this report so that such mistakes are never repeated.”

In a statement to the committee’s inquiry, Merthyr (South Wales) Limited said it had reached a formal agreement with the council to initiate “an interim restoration programme” at the site.

This would allow an additional 54 hectares (133 acres) of land west of the mining cavity to be repaired.

The company said it had engaged “the services of a number of external consultants, specialists in their field” to prepare a revised mine rehabilitation plan and said it would “not be appropriate to comment further” until it had been finalised and submitted to Merthyr Tydfil Borough Council for consideration.

A Welsh Government spokeswoman thanked the committee for its work on the issue “over the last few months”.

“We will review the report’s findings and recommendations and respond in due course,” she said.

Merthyr Tydfil Borough Council said it had noted the report’s recommendations.

It was also “welcome” that the Committee had thanked the Council for its “positive and constructive response” to the investigation.