Chris Copeman, Green party councillor for the Helsby ward of Cheshire West and Chester council, is grappling with two different cases of ‘forever chemical’ pollution by Polychlorinated Biphenyls or PCBs. At the Commonside tip in Alvanley, a long-abandoned waste site has been slowly leaching pollutants into the nearby Foxhill Brook for decades. And the old BICC plant in Helsby, which closed in 2000, has been redeveloped; but recent testing by the BBC Last Witness podcast showed that PCBs persist in the Hornsmill Brook that runs through the site. Both water courses run into the Mersey nearby, where pollutants such as PCBs can be concentrated in the food chain. He has called for a public enquiry into the situation.
Copeman says: “I think a full evaluation of the [BICC] site and how well the containment is working is needed and Balfour Beattie [the BICC successor company] should be held to account. I also think more testing on the current areas where they are building should have been done. I think people buying houses or living there deserve to have a more thorough evaluation of the site. Contaminated soil has been taken from the site and the council environmental team don’t even know where it’s going. People’s houses have been sprayed with dust off the site all summer. I’ve had quite a few concerned residents contacting me.”
Brownfield construction is complicated
“Build on brownfield sites” is often suggested as one of the solutions to the shortage of UK housing and the resistance of local communities to developing in the countryside. But often, such sites have a legacy of contamination that remains decades after the industry that once thrived there has closed, and the buildings have been demolished. Legislation (notably the Environmental Protection Act of 1990 or EPA) is in place that specifies how potentially contaminated land should be handled. This sets out a statutory definition of contaminated land which requires a judgement as to whether there is a significant possibility of significant harm being caused by the contamination.
But – even if the correct procedures are followed – can we be confident that such redeveloped land is safe and no longer a risk to construction workers, residents and local water courses?
The BICC plant at Helsby, which once made cables and electrical equipment, closed down in 2000. Over the past 24 years, the site has been progressively redeveloped with a large Tesco store, hundreds of houses, retirement homes and a community sports and social club. Other industrial units on the site also closed and have been or are being developed, mostly for residential use. Construction is continuing today.
To be clear, there is no evidence of any health issues among the local population. The proper procedures have been followed. Approximately 20 major planning applications have been submitted and approved since 2003 and a dozen or more environmental assessment reports by several different consultants have been completed; remediation plans have been developed and approved.
EPA procedures were followed throughout development
The possibility of contamination with PCBs was considered from the start of the redevelopment project. PCBs are a family of stable, long-lasting chemicals which are known toxins and were used in electrical equipment before their production was banned in 1976 in the UK. PCBs were in use at the BICC plant and some – but not all – of them ended up in the nearby Commonside tip.
In the late 1980s, in preparation for the closure of the plant, BICC parcelled off an area of the site that had been used as a PCB dump and constructed a so-called containment cell, using a clay bund and an impermeable membrane. This was intended to capture any PCB-contaminated ground and surface water and feed it to a PCB treatment plant to remove PCBs from the water before being discharged into the Hornsmill Brook, which runs through the site. This plant still operates today (it is run by infrastructure company Balfour Beatty who were part of BICC and are essentially the successor company).
At each stage of the development, environmental assessments were made a condition of planning permission being granted. Site surveys included the digging of boreholes for the purpose of taking samples, and measurements were made of PCBs, other organic materials, and heavy metals.
PCBs have been detected throughout the site
In a small proportion of the samples taken, PCBs were found at high concentrations. It’s important to put some context on this. The background concentration of PCBs in the UK is approximately 0.002 mg/kg (milligram per kilogram). The most dangerous PCBs – a group of PCBs known as the WHO 12 – are a concern if concentrations exceed 0.01 mg/kilogram, while for the EC7 group of most common PCBs the danger limit is around 1 mg/kg.
For example:
“14 samples found PCB concentrations above 0.05 mg/kg, three were above 1 mg/kg, with a maximum of 4.65 mg/kg.” [1]
“Sum of detected PCB 7 congeners ranged from 0.0097mg/kg in SB33 at 0.9m to13.7mg/kg in SB1 at 0.4m. Sum of detected WHO 12 PCBs ranged from 0.0696mg/kg in the spoil heap to 5.04mg/kg in SB1 at 0.4m.” [2]
“Elevated concentrations of PCBs were found in a sample from P1025 and to a lesser degree in BH101” [3]
[1] Planning application APP/2002/2007 Document “Conceptual model and remediation strategy for a proposed residential development at Mere’s Edge Development site, Helsby” by Joynes Pyke Associates (JPA).
[2] Planning application 22/00540/DIS Document “Phase II Environmental Site Assessment August 2018”, by Stantec SB1/SB33 are sample locations used during the study.
[3] Planning application APP/2002/2009 Document by Atkins (“Environmental Assessment Pt1/2 – forming part of planning submission for Mere’s Edge Development”). This found a EC7 PCB concentration of up to 1000mg/kg and 210mg/kg in the same borehole at different depths. P1025 and BH101 are sample locations used during the study.
This pattern of high readings at points across the site is not unexpected. It’s indicative of historic spills, abandoned equipment and old drains.
Watercourses were considered too
Humans and controlled watercourses such as the Hornsmill Brook must be given equivalent weight when assessing the risk of significant harm. Studies have considered the risk to controlled waters as one would expect. For example:
“the risk to watercourses has been assessed and has been shown to be negligible.” [1]
“The risk to the brook is considered low” [2]
“information provided gives us confidence that the risk to controlled waters at the site is low” . [3]
[1] in the JPA document “Hydrological and Hydrogeological Assessment” filed under APP/2002/2007, JPA reports that approved modelling software indicates that the rate at which contamination would migrate to the Hornsmill Brook, based on the most pessimistic assumptions was very low
[2] A more recent study by Delta-Simons (Remediation and Verification strategy: Delta-Simons Project No: 18-1479.03 February 2022) found under 22/00540/DIS undertook an assessment of Hornsmill Brook in the southern part of the site.
[3] The Environment Agency considered the remediation measures proposed to deal with contamination under the 2020 planning application 20/00324/FUL (for the southern end of the site, which includes the Hornsmill Brook)
Councillor Copeman has been reassured by Balfour Beatty that the PCB treatment plant is monitored continuously and there are no PCBs in the water discharged into Hornsmill.
But PCBs are still present in Hornsmill Brook
And yet a recent sample had 12000 times the expected background level of PCBs in the sediment in Hornsmill Brook which runs through the site – this featured in episode 6 of the “Buried – the Last Witness” podcast (available on BBC Sounds). The series looks at a series of different PCB contamination cases in the UK and undertook some chemical analysis of soil samples from 10 different locations, including Hornsmill Brook. The expected background level for PCBs is 2 ug/kg, which is given in a 2007 Environment Agency document “UK Soil and Herbage Pollutant Survey”. The scientist who carried out the work says it was the highest reading he had ever come across. Is there a previously undiscovered source of PCBs getting into the Hornsmill Brook? Given that the government mandated procedures were followed, what lessons can we draw from the Helsby experience? This will be the subject of the next article in this series.
