Coal tips, also known as coal spoil or slag heaps, and overburden are large mounds of waste soil, rocks, and fragments of coal that was dumped there as it was originally in the way between a mining company and the profitable coal it wanted to mine. Sometimes, mining companies promised to return these coal tips down the holes or into the voids they created, but often claimed bankruptcy or found loopholes to avoid this costly process. There are over 2,500 coal tips peppering Wales alone.

The coal tip slip in the town of Cwmtillery on Sunday 24th November 2024 occurred during Storm Bert, which brought intense rainfall. The coal tip is Category D, which means it is monitored every 6 months – and the last report did not flag any major issues. It follows on from the coal tip slip in 2020, which sent 60,000 tonnes of soil and rocks tumbling in Tylorstown, Rhondda Cynon Taf. That compares with 40,000 tonnes of debris that were dislodged and tumbled into a school in the infamous Aberfan disaster of 1966. Unlike the Aberfan tragedy, the two recent coal tip slips luckily resulted in no loss of human life.

What each of these coal tips have in common is that they occurred after a period of heavy rain. Leader of Blaenau Gwent council Steve Thomas commented on the recent coal tip slip in Cwmtillery, saying "We can confirm that we are dealing with a localised landslide believed to be caused by excess water as a consequence of weather experienced during Storm Bert."

Geologist Dr Jamie Price explained: "Both more prolonged and more intense rainfall events will heighten the risk of coal tip collapses….Increases in the moisture content of the coal tips and increases in groundwater level in general can affect the stability of these coal tips and could induce failure and collapsing of the coal tips."

A Cabinet Statement by the Welsh Government in 2023 stated “Winter rainfall has increased in Wales in recent decades, and the Met Office predicts that it will increase further as a result of global warming.”. By 2050 it's thought it could get 6% more rainy in winter in Wales, with as much as 13% more rain by the 2080s. Human-induced climate change made the heavy storm downpours and total rainfall across the UK and Ireland between October 2023 and March 2024 more frequent and intense, according to a rapid attribution analysis by an international team of leading climate scientists. This is exactly what we recently experienced with Storm Bert which led to the most recent coal tip slip in Cwmtillery.

ERI Ltd is a mining company that’s seized on community fears in Bedwas, South Wales, to propose mining two of coal tips in the area of around 500,000 tonnes of ‘waste’ coal contained within them on the promise of levelling out the coal tips afterwards. ERI Ltd is tempting Caerphilly County Council with the offer to do this at no cost to the Council, claiming it’ll use a portion of the profits gained by selling the coal it removes from the tips. The problem with this approach is:

1. ERI Ltd is driven by profit, not community concerns so will leave the coal tip closest to Bedwas residents, likely because this wouldn’t be as profitable for the company to mine.
2. Not all Category D coal tips have stability risks – having a one-size-fits-all ‘level it’ approach could needlessly decimate vital ecologies that have slowly emerged around many coal tips over the decades.
3. There is a strong pattern of coal companies abandoning their remediation promises as soon as they’ve sold the coal – which is why thousands of the coal tips exist today. ERI Ltd has little in assets to seize if it does abandon the site years from now. Just this year, Merthyr (South Wales) Ltd abandoned its remediation promises amidst record profits. Similar to ERI Ltd’s proposal, the Ffos-y-fran coal mine was billed as a project to remediate derelict land through coal extraction, but has left it infinitely worse.
4. Coal is the dirtiest fossil fuel and still the number one fossil fuel driver of climate change globally. If coal tip remediation is allowed to be used as a smokescreen for new coal mining, it’ll contribute to fuelling the climate change that’s threatening the stability of all coal tips.