In The National's first piece in this series on historical toxic waste in Wales, the legacy of the former Monsanto chemical factory in Newport’s was highlighted. 

Its carcinogenic waste was dumped during the 1960s and 70s at two disused quarries in what is now Rhondda Cynon Taf, leading the Environment Agency at the time to describe one as “the most polluted site in Britain”.

But what has happened to the Newport site since then, and does it still pose a threat?

The chemical factory in Newport responsible for those heavily polluted sites was originally built by Monsanto in 1949, and created numerous harmful products throughout the 1950s and 60s, including carcinogens such as PCBs.

In 1997, Monsanto created a new company. Many believe it was formed in order to survive incoming class action lawsuits relating to the carcinogens which were produced for the consumer market.

Solutia was then bought in 2012 by Eastman, although since the divestment, Monsanto has paid out billions in compensation to customers who used its weedkilling products in the US. It was also reported to have made a payment of $820m to settle a number of outstanding claims related to PCBs, which it had produced until 1977, despite being aware of its harmful properties as early as the 1950s.

The National Wales: Reception building at former Solutia site, now owned by Eastman. Photo: M J Roscoe CC BY-SA 2.0Reception building at former Solutia site, now owned by Eastman. Photo: M J Roscoe CC BY-SA 2.0

In 1960 a 3km effluent pipeline was built from the factory underground, beneath the village of Nash and the Gwent levels, where it discharged into the middle of the Severn Estuary.

With increasing evidence of how harmful PCBs were, a meeting was held in Newport in May 1970 with Monsanto staff from across the globe to discuss how they would deal with the ongoing discharge of PCBs to the environment. 

Meeting minutes published decades later show that the immediate target should be for discharge of PCBs to be “no greater than that which matches the solubility of PCB in water i.e. 200ppb [parts per billion]”.

The minutes note that a target in the US had been set to reach 10ppb by the end of 1971.

Monsanto’s own measurements of PCB levels downstream of their effluent discharge pipe in 1969 recorded levels of 2068ppb of PCB.

The National Wales: Notes from a 1970 Monsanto meeting which show dangerously high levels of PCB in the Severn estuary.Notes from a 1970 Monsanto meeting which show dangerously high levels of PCB in the Severn estuary.

The Newport chemical factory continues to operate to this day on a site that covers 100 acres to the south of the city. And in spite of efforts by the current owners Eastman to mitigate the effects of what they call “legacy substances” with the use of reed beds, the historical damage is still felt to this day.

Before the plans were scrapped in 2019, the M4 relief road was due to pass by the southern edge of the former Monsanto site before a new bridge crossing the Usk was to be built. The Welsh Government’s planning documents relating to the new bridge mention “the industrial legacy around the watercourse” being responsible for “elevated PCB concentrations”.

Another Welsh Government document reveals that there’s a “PCB waste disposal cell at Solutia Chemical Works” - suggesting the long-term storage of the harmful waste on-site in the absence of means to dispose of it safely.

Although the site no longer produces PCBs, it falls under the Control of Major Accident Hazards (COMAH) Regulations because of the use of what are considered “upper-tier” hazardous substances - these include phosphorous trichloride, benzene and heavy fuel oil.

As a result of being an upper-tier COMAH site, Newport City Council has had to draw up a plan of action in case of anything going wrong at the plant.

The document outlines the roles that different public agencies would take, how information would be communicated and which areas would need to be evacuated in the case of an ecological disaster at the site.

Newport Council’s emergency planning document reveals that the only potential Major Accident to the Environment (MATTE) as defined by the COMAH regulations, is if the effluent pipeline should fail and contaminate the network of ditches and reens which have crossed the Gwent levels for centuries.

The National Wales: The course of Solutia's Newport effluent pipe which discharges waste including PCBs directly into the Severn (Image: Newport City Council).The course of Solutia's Newport effluent pipe which discharges waste including PCBs directly into the Severn (Image: Newport City Council).

Discharge of harmful materials is permitted from the site within certain parameters. When Solutia’s operating licence was renewed in 2018, it the company to release 100 grams of PCBs a week (about one hundred times less than the emissions recorded in the 1960s), directly into the Severn - the river is a Site of Special Scientific Interest. It’s also a Special Area of Conservation, along with the nearby contaminated Usk river.

When it comes to emissions of contaminants, including PCBs, Eastman measures its own discharge and reports quarterly to Natural Resources Wales. According to their own numbers, a weekly mean discharge of 8.75g of PCBs was recorded during 2021, which is astonishing considering the fact that PCBs haven’t been manufactured there for more forty years.


Eastman’s annual performance report document, which it submits to the public register held by Natural Resources Wales, revealed in 2021 that its effluent pipeline suffered two failures - one was on-site, and the other was in the intertidal area of the Severn Estuary.

In correspondence seen by The National, Natural Resources Wales reveals that the replacement of the effluent pipe on its final section to where it discharges will take place this year, although other “leaks that have been identified to date are not considered to be of any environmental consequence”.

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