Willenhall Gas Works – Revocation Of Determination

The appeal into the remediation notice served in respect of properties at the Stonegate Housing Estate, the site of the former Willenhall Gas Works, is the most extensive consideration so far of the process of determining land as contaminated and is discussed at length in the text.  The remediation notice was quashed on appeal, on the ground that the local authority, Walsall Metropolitan Borough Council, had failed in making its determination, to act in accordance with the applicable statutory guidance, in that it had not undertaken a risk assessment based on sound science, which would allow it to conclude that the land in question represented a significant possibility of significant harm, and so had unreasonably identified the land as contaminated.

Following this, Walsall MBC commissioned a new firm of consultants (LQM) to carry out further sampling and a risk assessment. LQM concluded that while there were greater than background concentrations of contaminants associated with historical industrial activities including waste disposal from the gasworks, the assessment found that the concentrations of contaminants did not represent an unacceptable risk to human health in the light of the statutory guidance.

At a special meeting of the Cabinet on 23 January 2019 it was resolved to revoke the notice of identification as contaminated land, pursuant to paras. 5.20, 5.21 and 5.22 of the guidance (unlike the position in Scotland there is no express statutory power of revocation in England).  Whether this is the end of the matter, given the serious financial harm suffered by some of the owners of the land in question as a result of its identification as contaminated, remains to be seen.

The full suite of LQM materials are available here. The most useful to lawyers is probably the interpretative report, which runs to some 152 pages.

The Non-Technical Summary is reproduced below:

(1) This document provides a non-technical summary of the investigation and assessment undertaken by Land Quality Management Ltd (LQM) on behalf of Walsall Metropolitan Borough Council (the Council) on land at Stonegate and Trent Park Estates, Willenhall (the Site) under the provisions of contaminated land legislation that came into force in 2000 as Part 2A of the Environmental Protection Act 1990 (as amended) (Part 2A). LQM’s work is fully reported in two technical documents presenting the factual and interpretive aspects of our investigation and risk assessment.

2.1 Background

(2) The Stonegate and Trent Park Estates, Willenhall, were developed on or adjacent to land historically occupied by the former Willenhall Town Gasworks.

(3) Land at the two estates has been investigated by the Council since approximately 2006. For the purposes of these investigations, the Council split the land into 10 zones. These investigations concluded that 89 properties in three zones (zones 4, 5 and 7) of the estates met the statutory definition of contaminated land, on the basis of concentrations of benzo[a]pyrene (BaP) within shallow soils (0- 1m below ground level), and were formally determined as Contaminated Land by Council officers, under delegated powers, in March 2012 and the developer notified in August 2012. In March 2015, the Council served a Remediation Notice on the developer with respect to zones 4 and 7. This Notice was subsequently appealed by the developer in April 2015. In April 2017, the Secretary of State for the Environment upheld the developer’s appeal and quashed the Council’s Remediation Notice. The Secretary of State specifically found that the Council had “unreasonably identified the land as Contaminated Land”.

2.2 LQM Investigation

(4) LQM were commissioned by the Council in July 2017 to advise on whether or not the Stonegate and Trent Park Estates meet the definition of Contaminated Land in the updated 2012 legislation and statutory guidance. LQM reviewed the available site investigation data and identified the need for further detailed risk assessment based on additional sampling of natural and manmade soil at up to 89 residential properties within the determined zones 4, 5 and 7 and monitoring of groundwater and ground vapours within public open spaces. In February 2018, the Council commissioned LQM to undertake this additional site investigation.

(5) Site investigation works, conducted during February – March and May 2018, involved sampling from hand-dug pits in the rear gardens of the majority of the 89 properties and the installation of groundwater and ground vapour monitoring wells in public open space areas. Permission for soil sampling was not granted for 6 properties, 3 of which had limited historical contamination data. The ground conditions consisted of manmade soil (made ground) beneath, in most locations, a layer of topsoil. Made ground was very variable and contained fragments of brick, masonry or materials associated with the gasworks such as coal and occasionally coke or clinker. Samples taken were tested for substances associated with the heating of coal on former gasworks sites, including polyaromatic hydrocarbons (PAHs); metals (namely arsenic, lead, chromium and hexavalent chromium); cyanide compounds (total, free and thiocyanate); asbestos and soil properties, including pH and Soil Organic Matter (SOM). Groundwater and ground vapour samples were also taken between May and September 2018 from boreholes installed within the public open space. Samples were analysed by a laboratory using accredited test methods.

(6) The site investigation data collected by LQM and the previous investigations were combined to produce a dataset comprising analyses of soil samples, primarily collected from shallow (within the first metre below ground level) top soil and made ground within rear gardens of the determined properties. LQM used this information to carry out a risk assessment to help the Council decide if the land was Contaminated Land under Part 2A.

(7) Under Part 2A, the Council needs to decide whether land poses a “significant possibility of significant harm” (SPOSH) before it can be determined as Contaminated Land. A detailed risk assessment, including the toxicological assessment and assessment of potential hotspots, suggested by the Secretary of State, was therefore carried out by LQM.

(8) Gasworks waste materials contain mixtures of substances made of carbon and hydrogen that are known as polyaromatic hydrocarbons (PAHs). LQM showed that this was the likely source of contamination and the PAHs in the soils were therefore linked to the incomplete combustion of coal during the operation of the former gasworks rather than any other process. LQM showed that the risks from PAH mixtures in soil could be understood by assessing benzo[a]pyrene (BaP), the most important PAH. Elevated concentrations of BaP (and other PAHs) appear to be associated with the discrete fragments of clinker, coke and coal observed in the soils. LQM showed that the toxicity of reported in scientific literature as being harmful; a ‘toxicological assessment’. This showed that exposure as a consequence of normal domestic activities was unlikely to represent SPOSH.

(9) As part of the risk assessment process, LQM calculated exposure to soil contaminants at the Site using standard Environment Agency software and compared the estimated exposure against doses

2.3 Conclusions

(10) The work undertaken by LQM concluded that there are greater than background concentrations of contaminants at the Site associated with historical industrial activities including waste disposal from the gasworks. However, LQM’s site investigation and subsequent assessment of the combined results has found the concentrations of contaminants in the soils at the Site do not represent an unacceptable risk to human health when considered in light of the Statutory Guidance. This means the land should not be considered ‘Contaminated Land’ under Part 2A of the Environmental Protection Act 1990. the PAHs could be represented by the toxicity of benzo[a]pyrene (BaP) alone. LQM evaluated the combined site investigation evidence and concluded that it did not indicate the presence of hotspots of contamination.


Text references: 3-100; 3-101 – 3-112;


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