1. Background
This briefing supports the Petitions Committee’s short inquiry into the Hafod Landfill site. It updates the earlier briefing published for the Committee’s first consideration of this petition on 28 April 2025.
Mersey Waste Holdings was granted permission to run the former Hafod quarry site as a landfill in 2004, following a public inquiry. Wrexham County Borough Council (CBC) had previously rejected the company’s application. Since November 2008, it has been operated by Enovert North Ltd. (formerly Cory Environmental Limited). The landfill operates under an environmental permit (EPR-PP3139GB) issued by Natural Resources Wales (NRW). NRW regulates waste sites in line with its regulatory principles.
Hydrogen Sulphide (H2S) is a gas that is released during the decomposition of organic matter and is associated with landfill odour. As set out in this April 2025 local authority scrutiny report, there were a significant number of complaints relating to odour from the site during 2024. The petitioner has called for NRW to revoke the site’s environmental permit.
In a February 2025 newsletter update, NRW explained the circumstances under which it is able to revoke an environmental permit:
Hafod Landfill operates under an Environmental Permit, which sets out the types and amounts of waste that can be accepted at the site. The permitting regulations do not allow us to include restrictions on where waste comes from.
We only revoke permits if we believe the operation poses a serious risk to the environment or human health, and if all other measures to reduce the odour have been exhausted. At present, the operators are still working through a number of actions to address the issues, and we are regulating them closely.
Closing the site would not immediately get rid of the odours, as leachate and landfill gas would still need to be managed to reduce the potential for offsite odours.
Our regulatory actions are guided by our published regulatory principles, ensuring a balanced and proactive approach.
NRW summarises the findings of its site inspections, audits, and monitoring activities in Compliance Assessment Reports. A February 2025 compliance report for the Hafod Landfill details 5 ‘non-compliances’ of environmental permit conditions, relating to:
§ leachate management;
§ landfill gas;
§ chloride monitoring; and
§ surface water monitoring.
There were 26 instances of landfill methane emissions exceeding the permitted amount during the final quarter of 2024.
An NRW webpage outlines its ongoing regulatory actions for the site, including:
§ regular site inspections;
§ reviewing Enovert’s management procedures and action plans; and
§ working with Wrexham CBC to ensure air quality and monitoring meets Welsh Government standards.
NRW says it told Enovert to take action to reduce long-term fugitive (unintentional) emissions in late 2024. It also issued Enovert with an Enforcement Notice on 21 December 2023, which included “several actions that needed to be taken to address the odour complaints reported between October and December 2023”. NRW says Enovert complied with the notice, completed related works, and updated its action plan related to its management procedures.
Its March 2025 update says Enovert has installed new infrastructure to increase the volume of gas being collected from the site, and that further air quality monitoring equipment will be installed in the near future. On odour emissions to residential areas, NRW says:
“Under the conditions of the Environmental Permit, if the operator is taking appropriate measures to control odour, a breach of the permit does not occur, even if some odour is still detectable. The site operator has identified appropriate measures within their odour management plan to manage odour emissions; however, we understand that there continue to be impacts on the community. We are closely reviewing their plan to determine if any additional measures are needed to further mitigate odours.”
The Hafod Landfill Stakeholder Group was established in early 2025, following a rise in odour complaints. The Stakeholder Group includes Enovert, NRW, Wrexham CBC councillors and officials, and community council representatives. It had its first meeting on 21 March 2025. Additionally, the Hafod Liaison Group was established over 20 years ago as a forum for dialogue between the operator and the local community. It is chaired by a local councillor and includes Enovert, NRW, local Wrexham CBC councillors and officials, community councillors, and four local residents.
In its most recent (May 2025) update, NRW says the number of odour incidents has “shown a steadily decreasing trend as improvement works are completed”.
2. Written evidence submitted to inquiry
The Petitions Committee carried out a consultation with key Hafod Landfill stakeholders in July and August 2025. This section summarises the written responses the Committee received.
2.1. Enovert
Enovert’s submission details its waste management role and how it is regulated. It says the degradation of waste in landfill produces landfill gas and leachate. The landfill gas is collected for use as fuel, whilst the leachate is stored in tankers for later processing at wastewater treatment facilities. Enovert provides detailed information on the types of waste it accepts and the source of that waste.
In relation to odour, Enovert says it takes complaints seriously and investigates and reacts to each one. It says it took remedial action both before and after it was issued a Statutory Notice by NRW in December 2023, and that it complied with all actions on agreed timescales. Its response includes a list of works it undertook between October 2023 and July 2025. Enovert says it installed four monitoring stations around the site, and it has appointed “leading independent environmental consultants” to assess the data. It says it followed the consultancy’s recommendation to install “additional diffusion tube monitoring devices to provide accurate detail in respect of actual exposure risk”.
Enovert says that, following a meeting with the Wrexham CBC Homes & Environment Scrutiny Committee, it agreed to part-fund an air quality monitoring scheme. The scheme includes monitoring hydrogen sulphide gas on site and in the community. In relation to publishing that data, Enovert says:
“The monitoring exercise needs to gather a sufficient body of data to allow proper assessment of the air quality environment. We are awaiting the data from the instruments for the third monitoring period at the time of writing. We have agreed to provide the latest monitoring data summary, with the benefit of the third round of monitoring detail, to the Senedd Petitions Committee by 15th September for inclusion in our evidence.”
The latest data is not available at the time of preparing this briefing. However data for March 2025 can be found in a report produced for the scrutiny Committee.
The response goes on to rebuke specific claims made in the petition. It also details the volume of landfill gas extracted from the site since November 2023, which has stabilised and (on average) fallen slightly.
Enovert provides information on the source of waste inputs to Hafod during 2024. It says around 10% of all waste is residual ‘black bag’ waste diverted from Energy from Waste plants. Just over half of the 2024 input (54%) came from England, with most of the remainder coming from north Wales. This is summarised below.
Hafod landfill 2024 inputs by nation and local authority area.
Source: Enovert
2.2. Public Health Wales
Public Health Wales (PHW) submitted evidence detailing its involvement with Wrexham CBC in relation to odour at Hafod.
PHW provides advice on guideline values for assessing public exposure to hydrogen sulphide over different time periods. It says it does not need to be informed of routine findings “unless the data shows significant concerns e.g. concentrations are routinely above the exposure standards”. It also advises that occupational exposure standards are inappropriate for assessing public exposure.
PHW also provides information on assessing the concentration of Volatile Organic Compounds (VOC) in air, which does not include hydrogen sulphide. It suggests benzene could be used as a conservative proxy for assessing the health risks of VOC unless Wrexham CBC can establish “an informed estimation of what VOCs are likely to be present”.
2.3. Natural Resources Wales
NRW says Enovert’s Environmental Permit “requires the operator to prevent odour off site or, where that is not possible, to keep it to a minimum”. It says Enovert’s Odour Management Plan describes how it will achieve this condition. And that any updates to its Plan must be assessed by NRW officers.
The response details NRW’s approach to odour investigation, which includes site investigations and a odour intensity scale. It says a breach will only be recorded when on-site activities are likely to cause off-site pollution, and the operator is not taking all appropriate measures to control odour.
NRW says it can only initiate the closure of a landfill “when the management of an operational site is poor and further operation of the site may result in significant, long-term pollution”. It says a closure notice is only used “when other enforcement options have been exhausted”.
NRW provides a timeline of significant events in the regulatory history of Hafod, which are summarised in the table below:
Recent history of NRW’s regulatory activity at Hafod
|
Date |
Event |
|
October 2023 |
Large increase in odour incident reports. |
|
21 December 2023 |
NRW issued a Compliance Notice to Enovert to address odour. |
|
31 January 2024 |
NRW satisfied that Enovert had complied with Notice. |
|
8 March 2024 |
More gas emissions identified, Enovert proposes more remediation measure. |
|
13 May 2024 |
NRW follow-up visit finds overall improvement, but some transient odours still detected. |
|
November 2024 |
NRW’s Landfill Emissions Reduction Project (LERP) team audits Hafod, gives recommendations and actions to Enovert in a Compliance Assessment Report. |
|
December – January 2025 |
Escalation in odour incident reports. NRW officers confirm offsite odour is present. |
|
After January 2025 |
Odour incidents reports decrease. NRW makes unannounced inspections and site audits. NRW considering additional enforcement on leachate. |
NRW also provided a more detailed history of recent enforcement action to Wrexham CBC’s Home and Environment Scrutiny Committee meeting on 29 April 2025.
2.4. Wrexham CBC
Wrexham CBC’s submission to the inquiry describes the history of the site and the council’s work in addressing community concerns about the landfill.
Its Homes and Environment Scrutiny Committee considered complaints about the site during meetings in June 2024 and April 2025. It also produced a report in October 2024. Key recommendations arising from the most recent meeting include:
§ consideration of another update report in 6 months – the report should detail any site-related toxicity and associated health impacts;
§ the council should explore expanding air quality monitoring in the community; and
§ if monitoring shows odours “above accepted limits”, Wrexham CBC should explore its powers under the Environment Protection Act 1990 (the 1990 Act) to tackle these.
Wrexham CBC says its officers have enforcement powers to tackle ‘statutory nuisance’ under the 1990 Act , but its policy is for the organisation with primacy (in this case NRW) to implement formal actions. It says any local authority-led prosecution would require the consent of the Welsh Ministers.
The Council says its officials determined the best options for air quality monitoring for hydrogen sulphide and volatile organic compounds. Four AQMesh Pod monitors were installed by Enovert around the Hafod Landfill in February and March 2025, and are operated by the company. An additional monitor was installed and is operated by Wrexham CBC at the Johnstown Community Centre, and a second monitor is due to be installed at the Johnstown and Nant Parc Bowling Pavilion. Data from monitors “can be checked in real-time by [Wrexham CBC] Public Protection, NRW and Enovert personnel”. However, Wrexham CBC qualifies the interpretation of this data:
“It is important to stress that the data from AQMesh Pods is qualitative. Quantitative data can only be provided when a stringent QC plan is in place with access to reference instruments. The options to implement this process is being pursued with Enovert and Geotechnology.”
In addition to the AQMesh Pods, Wrexham CBC says hydrogen sulphide diffusion tubes have been co-located with the monitors and also deployed in other nearby locations. It says this is “to determine the accuracy of the real time monitors and check for other sources of H2S”.
Data interpretation is to be done through a company called Geotechnology, which is being employed by Enovert. It says reports are being provided to the Council, NRW, and Enovert, and “will be accessible to the public via NRW’s citizen web pages”. It is unclear whether the raw data itself will be published. Wrexham CBC says it has altered its interpretation of hydrogen sulphide thresholds following correspondence with Public Health Wales, and it will now compare readings to World Heath Organisation (WHO) air quality guidelines and Acute Exposure Guideline Levels (AEGLs).
Wrexham CBC officers conducted daily assessments of odour levels around Hafod Landfill from mid-July to mid-August 2025. In 85% of assessments, no odour was detected. When odour was detected, this was most commonly at one of 3 sites immediately adjacent to the landfill on its eastern boundary. Wrexham CBC says its results “indicate that no statutory odour nuisance currently exists, relating to the Hafod landfill site at the current time”.
2.5. Wrexham councillors
Three Wrexham CBC councillors representing wards around Hafod Landfill submitted a joint response to the Committee’s inquiry, they were:
§ Cllr David A Bithell (Deputy Leader of the Independent Group);
§ Cllr Steve Joe Jones (Independent Councillor); and
§ Cllr Dana Davies (Leader of the Labour Group).
The response says there have been fewer complaints during 2025 compared to previous years and that Enovert has recently been more proactive in working with other stakeholders. However, it caveats this by saying public communication needs to improve “to rebuild trust and demonstrate that action is being taken when problems arise”. The Councillors say they support “measures which will reduce odour, provide public health assurance, minimise complaints, and ensure accountability”, emphasising the need for ongoing support and oversight.
2.6. Residents
The Petitioner wrote to the Committee asking for clarity from NRW and Wrexham CBC in five areas:
§ the assessment of off-site health and nuisance impacts by NRW;
§ the exercise of statutory powers by Wrexham CBC;
§ the transparency of monitoring datasets;
§ enforcement in relation to hydrogen sulphide levels; and
§ perceptions of whether regulators are acting to protect the public.
Another resident responding to the Committee says that Enovert and NRW have sometimes attributed odours to agricultural activity, rather than the landfill.
Both the petitioner and other resident suggest that a recent decrease in complaint reporting to NRW may be attributable to “complain fatigue”, where residents no longer report odours “because they now feel that it is a waste of time”.
Residents expressed concern about their lack of representation in the Hafod Stakeholder Group, which was established earlier this year.
3. Welsh Government action
In his response to the petition, the Cabinet Secretary for Climate Change and Rural Affairs, Huw Irranca-Davies MS, says he met with NRW officials and Enovert senior management to discuss the Hafod landfill site on 19 March 2025. He says the site’s issues are regulatory and operational, so NRW is “best placed to determine the appropriate regulatory action and I therefore do not feel it is necessary to direct NRW to revoke the permit.” Enovert’s submission says the Cabinet Secretary wrote to the company after the visit:
“…to encourage Enovert to ensure compliance with the site’s Environmental Permit through engagement with NRW, and the importance of engaging with the public regarding any necessary maintenance and infrastructure works at the site”
4. Welsh Parliament action
The Petitions Committee initially discussed this petition on 28 April 2025. On 16 June 2025, it agreed to hold a short inquiry into outstanding issues related to the site. This involved inviting Enovert, NRW, and Wrexham CBC officials to give oral evidence to the Committee.
On 14 January 2025, Gareth Davies MS asked the Trefnydd for a statement related to the site, specifically raising constituent concerns about a large amount of waste being brought from England. He asked:
…could the Cabinet Secretary for climate change outline how the Welsh Government is working with the UK Government and local authorities in England to ensure that residents in north Wales do not have to pay for the failures of local authorities in the north-west of England?
The Cabinet Secretary for Social Justice, Trefnydd and Chief Whip, Jane Hutt MS, responded:
You've raised a very specific question and issue for the Cabinet Secretary and Deputy First Minister, and he will find an appropriate way to respond to that. Thank you for raising it.
On 28 January 2025, Mark Isherwood MS asked the Trefnydd for a statement on the Hafod landfill, citing Johnstown constituent complaints about smells and NRW’s “apparent lack of action in stopping it”. The Trefnydd said the point “will be recorded with the Cabinet Secretary for Climate Change and Rural Affairs”.
On 10 June 2020, following a fire at the landfill site, Llyr Gryffydd MS asked the then-First Minister, Mark Drakeford MS, for an independent inquiry into the cause of the fire and for the landfill’s closure in the meantime. The First Minister said multiple authorities have responsibilities to provide reports about the fire, and “the Welsh Government will consider those reports and then decide what further action may be needed.”
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Every effort is made to ensure that the information contained in this briefing is correct at the time of publication. Readers should be aware that these briefings are not necessarily updated or otherwise amended to reflect subsequent changes. |