However its criticism also extended to Merthyr Tydfil council, the Welsh government and other agencies involved in overseeing the mine during the best part of 20 years.
A report commissioned by the Welsh government in 2014 had set out “significant and clear warnings about the potential issues at Ffos-y-Fran” due to “insufficient bond cover”, the committee said.
While “best practice guidance” from the UK Coal Authority in 2016 called for the restoration liability at opencast sites to be reassessed annually.
“We must question whether the local authority and the Welsh government have taken all necessary steps to seek a better outcome for the local community,” the committee said.
It called for tougher enforcement action when planning rules were breached, and more involvement from residents in decisions around mining sites – including a requirement for a degree of community ownership of any future schemes.
While it is unlikely brand new opencast mines would be approved in Wales, due to climate change laws, the committee warned work to remediate old coal tips could lead to similar problems, especially where companies might look to extract and sell coal to fund efforts to make the sites safe.
The committee’s chairman, Llyr Gruffydd MS said residents living near opencast mines too often felt “completely failed by the public authorities who are meant to protect them”.
At Ffos-y-Fran, time was “quickly running out to secure what was promised for the local community”, he said, calling on all involved to “learn the lessons from this report, so these mistakes are never repeated”.
