We recognise the frustration caused by the ongoing odour impacts from the Northacre MBT site and therefore we want to provide a further update on our ongoing monitoring and regulatory work.

We are currently receiving an increased number of odour reports from residents in Westbury. As part of our ongoing regulatory response, we are assessing the impact of the recent site shut down period and improvement works. We are gathering evidence both on and off site to understand how effective the changes have been and whether further action is needed. We are considering all available regulatory and enforcement options and will not hesitate to take further action where the evidence supports it. We will share information about any enforcement action as soon as we are able to do so.

We understand that residents have concerns and questions which they would like addressed. To help with this, we are supporting a multi-agency drop-in event organised by Wiltshire Council, giving residents the opportunity to speak directly with representatives from the organisations involved in investigating and responding to the odour issues in Westbury.

Community Drop-in Event 17 August 2026

Westbury: Northacre MBT Odour Response Drop-in Event

Date: 17 August 2026
Time: 5:30pm-7:30pm (drop in anytime)
Location: The Laverton, 10 Bratton Rd, Westbury, BA13 3EN

Representatives from multiple agencies will be available to answer questions and provide information:

• Environment Agency - Site regulation. Contact: wessexenquiries@environment-agency.gov.uk
• Wiltshire Council – Responsible for Environmental Health and statutory nuisance investigations. Wiltshire Council is also the Waste Disposal Authority and is responsible for the management of contracts relating to the treatment of local authority waste, including waste delivered to the Northacre Resource Recovery Centre. For more information: www.wiltshire.gov.uk/article/1833/Smells-and-odours(External link)
• Health concerns, medical advice and Public Health issues – Wiltshire Council advise if you have any concerns about your health, please contact your GP or NHS 111 for individual medical advice in the first instance. If you have any further public health-related queries, you can email Wiltshire Council Public Health at publichealth@wiltshire.gov.uk, who can help direct your query to the most appropriate organisation for a response.
• Hills Waste Solutions – Site operations. Contact: www.hills-group.co.uk/contact-us/

Calne

Representatives from UKHSA joined the Environment Agency and Hills for a visit to Lower Compton Landfill site on Tuesday this week ahead of the public drop in event to view completed capping and gas extraction wells and understand how these works will help reduce odours from the site.

Our public drop in event on Tuesday evening at Calne Town Hall was well attended by members of the local community and local elected representatives. Staff from the Environment Agency. Wiltshire Council, UKHSA and Hills were on hand to answer questions and address concerns. The Environment Agency and Wiltshire Council provided handouts as part of the event that can be accessed to the right of this page under Calne Engagement event 21 July.

The gas extraction wells are being stabilised to ensure they are operating effectively. We will carry out daily monitoring from the start of August to assess whether the work has been effective in minimising odour from Lower Compton landfill.

Hills have issued an update on their website today which can be viewed by accessing the link below: https://www.hills-waste.co.uk/news/lower-compton-landfill-and-northacre-mbt-update

Westbury

After a period of closure for maintenance of one of the cranes in the biohall at Northacre MBT plant in Westbury the plant started accepting waste again on Monday 20 July. Work on the biofilters has been completed and the operator is continuing to make improvements detailed in their action plan. Wiltshire Council will be hosting a community drop in event in mid August and representatives from the Environment Agency will be in attendance to talk to residents and the community and answer questions.

We continue to receive a small number of odour reports and have officers in the community undertaking monitoring to see if the works have made the required improvements to on-site odour control.

We would like to thank the community of Calne, local MP Sarah Gibson and local Cllr Sam Pearce Kearney and residents for attending our multi agency drop in event alongside representatives from UKHSA, Wiltshire Council and the site operator Hills at Calne Town Hall last night to discuss odour issues associated with Lower Compton Landfill site. The Environment Agency shared two written updates with attendees. A link to these documents and a handout shared by Wiltshire Council can be found on the right of this page in the folder Calne Community engagement event. Thank you

Following on from yesterday’s air quality monitoring update, we would like to provide an update on this week’s progress at the Lower Compton Landfill and the actions being taken to address odour concerns affecting communities in Calne and the surrounding area.

This week, the Environment Agency visited Lower Compton Landfill to review site operations and progress against the action plan required by the Environment Agency. We can confirm that all permanent and temporary capping works have now been completed ahead of schedule. Hills has also confirmed that additional landfill gas wells will be installed from 13 July to increase gas capture and further reduce emissions from the site. The site operator has shared an update on the works here: https://www.hills-waste.co.uk/news/northacre-mbt-lower-compton-landfill-and-ukhsa-report

As outlined in our update yesterday on the publication of the UK Health Security Agency (UKHSA) Public Health Risk Assessment, monitoring data collected by the Environment Agency supports findings from our inspections and off-site odour assessments. The ambient air monitoring station remains in place and will help us to establish whether the work currently being completed by Hills is minimising landfill gas odour. We will carry out our assessment in August, once the installation of the permanent gas infrastructure has been completed.

As previously communicated, waste that would normally be processed at the Northacre Mechanical Biological Treatment (MBT) facility in Westbury continues to be redirected to Lower Compton while maintenance works are completed there. We have emphasised to Hills the importance of managing this waste appropriately and minimising any impact on local communities. Hills has confirmed that all additional waste diverted from Northacre MBT is being landfilled immediately to reduce any potential impact. Hills have shared that they expect the MBT plant will restart from Monday 20 July.

The Environment Agency will continue to regulate the site closely and carry out inspections and off-site odour assessments to monitor the effectiveness of the measures implemented. We will continue to work with Hills Waste Solutions, Wiltshire Council and UKHSA to ensure appropriate action is taken where necessary.

As previously announced, a multi-agency community drop-in event will take place on 21 July 2026, from 4pm to 7pm at Calne Town Hall, where residents can discuss the recent air quality assessment and ongoing work at the site with representatives from the Environment Agency, UKHSA, Wiltshire Council and Hills Waste Solutions.

Environment Agency staff monitoring at the Lower Compton site Jul 26

The UK Health Security Agency (UKHSA) has now completed and published a public health risk assessment using data collected by the Environment Agency's Mobile Monitoring Facility (MMF) in the Calne community, located at Priestley Primary School.

The MMF provides continuous air quality monitoring, including measurements of hydrogen sulphide, methane and particulate matter concentrations. We recognise the community's desire for transparency and openness; therefore, the full ratified dataset used to inform the assessment is available on our website.

The full UKHSA report, together with an executive summary, can be accessed here:

UKHSA PHRA Summary

UKHSA PHRA Full Report

We have also provided the Environment Agency Study of Ambient Air Quality at Lower Compton:

Environment Agency Air Quality Study

MMF Air Quality Dataset (Excel)

We, Wiltshire Council and UKHSA have also prepared a Questions and Answers (Q&A) to help explain the findings and address some of the questions residents may have when reading the report.

The ambient air monitoring data produced by the Environment Agency, and analysed in this report, shows that there is a source of hydrogen sulphide and methane in the direction of the Lower Compton Landfill Site. 

This confirms the findings of our inspections and off-site odour assessments, and supports the Environment Agency’s regulatory decisions, including requiring Hills to bring capping works forward and change the ways they manage odour.

Community Drop-in Event 21 July 2026

We are hosting a multi-agency drop-in event where residents can discuss the report's findings directly with representatives from the agencies involved in responding to the odour issues in Calne.

Calne Landfill Odour Response Drop-in Event

Date: 21 July 2026
Time: 4:00pm – 7:00pm
Location: Large Hall, Calne Town Hall, SN11 0EN

Representatives from multiple agencies will be available to answer questions and provide information:

• Environment Agency - Air quality monitoring, monitoring methodology and site regulation. Contact: wessexenquiries@environment-agency.gov.uk
• UKHSA - Technical findings of the UKHSA assessment and further information on UKHSA advice. Contact: enquiries@ukhsa.gov.uk
• Wiltshire Council – Environmental Health Team and statutory nuisance investigations. For more information: www.wiltshire.gov.uk/article/1833/Smells-and-odours
• Health concerns, medical advice and Public Health issues – Wiltshire Council and UKHSA advise if you have any concerns about your health, please contact your GP or NHS 111 for individual medical advice in the first instance. If you have any further public health-related queries, you can email Wiltshire Council Public Health at publichealth@wiltshire.gov.uk, who can help direct your query to the most appropriate organisation for a response.
• Hills Waste Solutions – Site operations. Contact: www.hills-group.co.uk/contact-us/

About the Monitoring Programme

The monitoring location at Priestley Primary School was carefully selected using a range of factors, including prevailing wind patterns, the predicted movement of landfill emissions and the geographical distribution of odour reports received from the community.

In addition to measuring air quality, the Mobile Monitoring Facility collected meteorological information such as wind speed, wind direction, temperature and atmospheric pressure. This data helps us understand when emissions may have occurred and whether they could be linked to landfill operations.

The monitoring programme supported our extensive field observations from Environment Agency officers who responded to odour reports across the community. Together, these sources of information have provided a comprehensive evidence base to support our ongoing regulatory work.

You can read more about the monitoring programme in our Questions and Answers.

Environment Agency regulation

The Environment Agency is responsible for regulating the landfill site and ensuring compliance with the conditions of its environmental permit.

As the environmental regulator, we have taken extensive action to require Hills Waste Solutions to address the source of the odour affecting the Calne community. These improvement works are now nearing completion.

We will continue to regulate the site closely and will take further enforcement action where necessary to ensure permit compliance and minimise environmental impacts.

Responsibility for investigating odour nuisance sits with Wiltshire Council. Public health matters are the responsibility of the UKHSA and Wiltshire Council through their director of public health. We will continue to work closely with both organisations.

Following on from our previous briefings, we would like to provide a further update on the odour concerns being experienced in Calne and Westbury.

Following the failure of the cranes at the Westbury Mechanical Biological Treatment (MBT) facility, Hills has taken the decision to temporarily stop accepting new household waste at the site. You can read more about Hills’ decision in their update here: https://www.hills-waste.co.uk/news/update-on-northacre-mbt-and-lower-compton-landfill

As a result, Hills has implemented its contingency plan, which has been agreed with Wiltshire Council, by redirecting household waste collections that would normally be processed at Westbury to the Hills facility at Compton Bassett, near Calne. This will enable collections to continue while Hills addresses the issue at the Westbury site.

We recognise that this change may increase concerns about odour in both communities, particularly with further periods of hot weather forecast. In Westbury, there may be increased odour associated with doors being opened to carry out the necessary repair work. We have inspected the transfer station in Compton Bassett today, ensuring that Hills are using appropriate measures to minimise odour from the additional waste being delivered.

We fully appreciate that this situation is far from ideal for residents. We are working closely and urgently with Hills and Wiltshire Council to identify and implement measures that will minimise the impact of the additional waste being processed at Compton Bassett and to reduce odour wherever possible.

Please be assured that officers will continue to monitor odour levels in Westbury throughout the weekend and will respond to reports from residents across the area as they are received. We understand how challenging waste-related odours can be, especially during periods of warm weather, and we remain committed to investigating concerns and taking appropriate action where necessary.

We are also continuing to work with Wiltshire Council and the UKHSA to arrange community engagement events in both Calne and Westbury. These sessions will provide residents with an opportunity to speak directly with representatives from the relevant organisations, ask questions, and share their experiences. Details of dates and venues will be shared as soon as arrangements are confirmed.

Progress continues with the capping works at the Lower Compton landfill site