Toxic chemicals from a suspected landfill site in Wales are leaking into a nearby forest (Picture: PA)

A landfill site in Wales may be leaking toxic waste into a nearby forest where children play, locals believe.

The Ty Llwyd Quarry in Ynysddu near Caerphilly is one of a number of sites suspected of being used by the chemical company Monsanto to dump pollutants into the environment decades ago.

This includes carcinogenic chemicals called PCBs from Monsanto’s now-defunct Newport factory.

PCBs were widely used in electronics for years until they were banned in 1981 after tests revealed them to be deadly to both humans and wildlife.

Although the council-owned Ty Llwyd Quarry was never officially a dump site, villagers say that after heavy rain a potent-smelling brown foamy liquid flows from the site down through woodland and past homes.

The council claims the liquid is just ‘normal surface water’ yet nevertheless urged people to stay away from the quarry and surrounding area during heavy rainfall.

Villagers remain concerned the substance is harmful and that it could be entering the Sirhowy River and eventually spill into the Celtic Sea.

The Ty Llwyd Quarry is believed to contain pollutants dumped decades ago by the chemical company Monsanto (Picture: PA)

Ynysddu councillor Jan Jones said she’s raised this with Caerphilly County Borough Council and the Welsh Government.

She said: ‘When it comes off (the quarry) it stinks. And that’s something you won’t experience by looking at the photographs – it’s absolutely stinking.’

Olwen Williams, whose brother’s farm in the village was bought under compulsory purchase because of contamination, said people are no longer allowed to grow crops or raise hens in the allotment by the site.

‘It’s concerning that there are no signs to warn people because we’ve seen children making dens in the forest, people walk their dogs there, teenagers having parties up there and people also go around (eating) the hazelnuts from the trees that were planted on that contaminated ground,’ she said.

Lifelong Ynysddu local Colin Prosser, 77, said the council was shrugging off their concerns.

He said: ‘This has been going on for 20 years, at least 20 years, and the council have been fobbing us off time and time again and it’s only recently they have said they are going to do something about it.

‘I was part of a subcommittee of local people – there was one of us from each village around here – who the council were supposed to keep informed about what they were doing to try and make it safe.

‘We were supposed to hear from them every six months but that fell by the wayside, and we ended up not hearing anything from them for years at a time.’

Manufacturing of PCBs, which were widely used in electric equipment, was banned in the UK in 1981 after tests revealed them to be deadly to humans and wildlife (Picture: PA)

In May 2021 the council had a drainage system installed designed to keep surface run-off separate from any contaminated liquid, also known as leachate.

However, photographs show a brown foamy liquid overflowing from the drainage system and spilling through a fenced-off area down the mountainside towards the village.

Standing by the quarry, amateur chemical pollution investigator the Rev Paul Cawthorne said: ‘Where we’re standing here, I would probably say it’s about the fifth or sixth most chemically contaminated site in the UK. 

‘And, as you can see, it’s just running straight down the hillside into the local village.

‘It’s not just that it smells, it’s the fact it’s chemical vapour which is a potential danger to health.’

Caerphilly County Borough Council has been reached for comment.

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‘That’s something you won’t experience by looking at the photographs – it’s absolutely stinking.’