Caerphilly Council allowed hazardous chemical to spill from Ty Llwyd Quarry onto road in Ynysddu

The chemical spilt into the surrounding woodland in Ynysddu. Credit: Bronwen Weatherby/PA

Caerphilly County Borough Council (CCBC) allowed liquid contaminated with hazardous chemical waste to spill from a landfill site onto a public road, an investigation has found.

The council manages the Ty Llwyd quarry in Ynysddu, just north of Cardiff, where toxic waste from chemical manufacturer Monsanto, including carcinogenic PCBs, was dumped in the 1960s and 1970s.

Natural Resources Wales found that following heavy rainfall in in January, contaminated liquid known as leachate was allowed to spill from the quarry and flow through a woodland used by children and dog walkers on to a public road.

At the time, residents said they were scared about the prospects of toxic waste in the area.

Reverend Paul Cawthorne said: "We saw evidence just up there [on the hill] of where children had been playing in the toxic flow. It scares me stiff thinking if they got PCB or something under their fingernails and then carry that back into the houses of Ynysddu. You know, where's the responsibility? And most importantly of all, where's the accountability?"

Another local resident added: "It's only a matter of time, in my opinion, before a very large amount of these toxic chemicals end up flooding down the side of the hillside and into this river."

The surrounding woodland next to the chemical spill in Ynysddu

After the initial reports, CCBC denied that any of the water leaving the woodland was contaminated, saying it treated the leachate in an aeration chamber, leaving "just normal surface water run-off".

Several days later, the chamber was found to be overflowing with brown foamy liquid that gave off a malodorous smell.

Samples were taken by independent councillors Jan Jones and Janine Reed and analysed by Greenpeace scientists. It found that the liquid was heavily contaminated with dangerous chemicals, including PCBs.

Environmental regulators Natural Resources Wales (NRW) said they attended the site on 3 January and have been investigating the pollution since, taking their own samples.

On 20 June they issued a warning to CCBC saying the council committed an offence of causing or knowingly permitting a water discharge activity and that pollution to land and water had occurred.

CCBC said in a statement: "NRW have completed their investigation of the contaminated water (leachate) breach that occurred below Ty Llwyd quarry in early January 2023 as result of a prolonged rainfall event.

"The level of rainfall caused the leachate drainage system serving the quarry to overtop, resulting in water containing leachate to leave owned land known as Pantyfynnon woodland and discharge on to the public highway below the site.

"Since the event, the council has continued to work in partnership with NRW in relation to Ty Llwyd and have recently entered in to pre-application discussions to determine whether there is a requirement for a formal water discharge consent to be in place at the site.

"Further technical assessments will be required to inform this process and the council will be working with their contaminated land consultants to progress this work and produce an updated management plan for the site."

Cllrs Jones and Reed said they feel vindicated after NRW's conclusion after repeated attempts to bring the contamination issue to the attention of the council and NRW.

"Good to know that NRW have now listened to the residents who live underneath the quarry," Cllr Jones said.

"We are vindicated. We have been saying for years that the council were illegally discharging contaminated water into the community forest and the private land below, ultimately ending up in the Sirhowy river."

Conservative Senedd member Natasha Asghar, who recently bid and failed to become the Conservative candidate for Mayor of London, has previously called for Ty Llwyd to be designated as contaminated land and wants the Welsh Government to step in.

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