Lower Compton landfill site, Calne
Lower Compton landfill site, Calne
What is this site?
Lower Compton Landfill site, Calne, is an active landfill site operated by Hills Waste Solutions Ltd.
It is one of several waste sites in the vicinity of the old RAF Compton Bassett airfield, east of Calne.
Hills Waste Solutions Ltd, hold an Environment Agency environmental permit to accept a variety of non-hazardous wastes.
The established landfill is made up of highly engineered cells for the deposit of waste. Each cell has a basal lining and surface capping systems to contain the wastes. A landfill leachate collection system removes liquid from the engineered cells and discharges the liquid to the sewer system, following treatment.
A landfill gas collection system collects naturally produced gases as the deposited waste biodegrades and is used on site as a fuel in engines that are generating electricity.
Map shows Lower Compton in Blue, Sands Farm landfill in Pink, Historic landfills pink hatch, Waste Management Licences (both current and historic) as red dots.
What activities are covered by the environmental permit?
The permit sets out how the landfill must be operated to ensure environmental protection, covering everything from the incoming waste to the management of gases, liquids, and overall site integrity, all with the aim of minimising any impacts on the surrounding community.
Our permits include a condition that requires operators to prevent odour leaving a site or, where that is not possible, to keep odours to a minimum.
The odour condition does not require the elimination of all odours outside the site boundary but states that emissions from activities shall be:
• free from odour at levels likely to cause pollution outside the site,
• as perceived by an authorised officer of the Environment Agency,
• unless the operator has used appropriate measures, including, but not limited to, those specified in any approved odour management plan,
• to prevent, or where that is not practicable, to minimise the odour.
As the regulator, it is the Environment Agency’s role to assess whether the operator is complying with the permit conditions, including managing odour effectively. Where operators are not complying with the permit, and we receive and can substantiate odour pollution reports, we may consider a range of interventions in accordance with our enforcement and sanctions policy.
We aim to make sure our enforcement response is proportionate and appropriate to each situation. We can provide advice and guidance, and where appropriate consider use of specific enforcement notices.
We will normally consider all other options before considering criminal proceedings.
How do we regulate this site and check for compliance?
In line with the permit conditions set we will undertake regular visits of the site to ensure compliance with conditions of the permit.
We will review the operator’s documents / data submissions . The operator is required to undertake routine monitoring and submit emission data to the Environment Agency
Where raised levels of odour reports have been made by the public, we will increase the frequency of visits to establish the effects of the activity on the area.
- The first is the waste odour. This is caused by fresh waste rapidly decomposing and tends to come from vehicles travelling to and from the site and whilst it is tipped. This is like odours that are contained within a domestic bin. It poses little risk to human health and can be tackled by depositing the waste quickly and covering it with soils called “daily cover.”
- The second type of odour is landfill gas. This is gas generated by the breakdown of the waste inside the body of the landfill site/cell. Landfill gas is mostly methane and carbon dioxide, which are odourless and colourless. However, landfill gas also contains trace components such as hydrogen sulphide that, even in very small quantities, has a strong smell of rotten eggs, which the human body is very sensitive to. Although the smell caused by the trace levels of hydrogen sulphide gas can be strong and unpleasant, it does not automatically mean that it is harmful. Our sense of smell is very sensitive, and we can smell hydrogen sulphide at very low levels.
- Close windows if there is an outdoor odour and open them when the outdoor odour has reduced. You could consider closing windows at night and opening them in the morning in the absence of odour.
- Ventilate the property when there is no odour indoors.
Environment Agency role in relation to landfills
We regulate a number of sites situated to the east of Calne in Compton Bassett, with activities including landfilling, materials recycling, composting, and waste transfer, under environmental permits held by the operators. The permit conditions aim to minimise the impact on the local environment, including odour.
Where we identify that an operator is not complying with their permit, we use our regulatory powers to bring the site back into compliance.
Calne Odour Reports
Odour Reports
| 2025 | 2026 |
January | 0 | 16 |
February | 2 | 101 |
March | 17 | 1510 |
April | 444 | 1342 |
May | 216 |
|
June | 49 |
|
July | 123 |
|
August | 82 |
|
September | 68 |
|
October | 9 |
|
November | 4 |
|
December | 0 |
|
NB: this data is for reports of odour received by the Environment Agency in the Calne area. We are not able to attribute all reports of odour we receive to Lower Compton Landfill, however we have confirmed it currently presents the main source of landfill gas odour in the area.
We have determined that the initial increase in reports at the end of January 2026 and into February was likely to have been caused by the installation of additional gas collection wells in the operational area of the landfill, which involved digging into recently deposited waste. However, we have continued to receive reports since this work was completed on 6 February 2026. Our recent inspections have found the main source of odour in the area is the current open landfill cell.
Timeline for Lower Compton Landfill site, Calne
Early 2025
The Environment Agency began to receive significant numbers of odour complaints from the local community, and our officers began odour monitoring in the local area.
April 2025
Although there are multiple potential odour sources in the area, we were able to identify Lower Compton landfill as the main contributor and served an enforcement notice requiring Hills to complete engineering works in a recently filled area of the landfill to reduce emissions. Fugitive methane emissions and strong odours were substantiated by Environment Agency officers to the northern of the site and permanent capping work to this area was bought forward from June 2025. The work was completed on 16 May 2025. The operator was required by us to carry out a surface emissions survey of the complete site infrastructure, which was completed on 2 April by a third-party contractor.
The recommendations from this survey were included in the action plan requested by us for the site.
Remedial works identified in our initial survey of the site on 4 April have been completed, along with remedial works identified by the surface emissions survey were completed by 2 May 2025.
Our officers conducted odour monitoring in the community with handheld hydrogen sulphide detection equipment.
June 2025
On 4 June Hills Waste Solutions Ltd were served with a Regulation 36 enforcement notice under the Environmental Permitting Regulations 2016, to complete capping work to the northern end of the landfill by 18 July 2025 and install permanent gas infrastructure over the same area by 31 July 2025. We conducted regular inspections of the work as it progressed, permanent capping and gas well installation work covered by the notice was completed.
A public meeting was held at Calne Town Hall on 11 June 2025 to listen and address residents’ concerns.
Our officers continued to conduct odour monitoring, including use of handheld hydrogen sulphide detection equipment. Officers conducted further inspections including walkover surveys using methane and hydrogen sulphide detection equipment, and an inspection of the capping works at the northern end of the landfill.
Contractor work required as part of the notice and agreed with Wiltshire Council as it required weekend, and extended hour working was completed.
July 2025
Site inspections concluded that odour emissions from the newly capped area to the north end of the landfill had significantly reduced.
We conducted regular inspections of the work under the notice as it progressed. Permanent capping and gas well installation work covered by the notice is complete.
We asked the operator to review their management systems.
August 2025
Our inspection on 1 August found highly odorous gas emissions from the area of the landfill where waste was being tipped.
We identified that the composition of the waste being deposited at Lower Compton had changed, with a higher proportion of the waste being ‘trommel fines.
Trommel fines are small particles which have passed through a rotating screen (trommel) as part of waste processing. While the composition of trommel fines depends on the material being accepted at the processing site, they are a mixture of organic and inorganic waste types including soil, sand, plastics, wood, and aggregates. This waste type contains a level of sulphate from sources like plasterboard, which when combined with organic material under certain conditions produces hydrogen sulphide, which is highly odorous and commonly found in landfill gas.
After we raised our concerns with Hills, they implemented additional measures to contain and collect landfill gas produced as the cell is filled. These included additional gas collection pipework, minimising the working area, and additional clay/soil cover on other areas of the cell.
October 2025
On 5 October we installed an ambient air monitoring station in Calne to provide continuous monitoring of hydrogen sulphide and methane levels in the community. Reports of odour continued to reduce to the end of 2025, with no reports received in December.
January 2026
In January 2026 reports of odour increased again. Although installation of the next phase of gas collection pipework infrastructure by Hills in the landfill cell being filled was identified as the reason for the initial increase, after completion of the work levels of reports remained high. As the process involved digging into waste, odour was more noticeable during these works. We established this activity was likely to be the cause of the increase in complaints at the end of January. The gas well installation work was completed on 6 February.
March 2026
The high volume and persistence of reports indicates that odour management on site at Lower Compton landfill is still not optimised and further regulatory intervention is required.
We continue to work to ensure that additional corrective measures are put in place to minimise the likelihood of further recurrences.
• We have increased the frequency of off-site odour assessments, including early morning and evening visits when odours are commonly reported
• Our focus is on the current cell of the Lower Compton Landfill (cell 26D), due to the change in nature of the waste inputs in this cell, with “trommel fines” accounting for a higher proportion of waste inputs compared to previous cells.
After we raised this with Hills in August last year, they implemented additional measures to contain and collect landfill gas produced as the cell is filled. These included additional gas collection pipework, minimising the working area, and additional clay/soil cover on other areas of the cell,
We are discussing with Hills what action they will need to take to optimise gas collection and improve control of gas in cell 26D.
We have determined that the initial increase in reports at the end of January and into February was likely to have been caused by the installation of additional gas collection wells in the operational area of the landfill, which involved digging into recently deposited waste.
However, we continued to receive reports after the work was completed on 6 February.
Our recent inspections have found the main source of odour in the area is the current open landfill cell.
We are continuing to conduct offsite odour assessments, including early morning and evening visits when odours are commonly reported. Our ambient air monitoring station has been in place in Calne since October 2025 and has now collected sufficient data on levels of Hydrogen Sulphide, Methane and Particulates in the community to produce an interim report. The data will now be validated and shared with UKHSA so they can provide updated public health advice; we will publish this report with the dataset once it is completed.
Our ambient air station remains in place, and we have extended the study due to the ongoing reports of odour in the community.
Following strong odour identified in recent inspections, we have required Hills to provide a short to long-term action plan identifying how they will minimise odour and emissions from this area, and the likelihood of reoccurrence in future cells.
We are currently discussing the scope and timescale of the actions required with Hills.
April 2026
We are conducting weekly inspections of Lower Compton landfill as improvements are made to ensure they are effective; this included a thermal imaging survey undertaken on 28 April 2026 to check for potential emissions from the operational area and surrounding cells.
Our ambient air monitoring station has been in place in Calne since October 2025 and has now collected sufficient data on levels of Hydrogen Sulphide, Methane, and particulates in the community to produce an interim report. We have extended the study due to the ongoing reports of odour in the community, and the air monitoring station will remain in place.
UKHSA will review and validate the monitoring data collected from the ambient air unit, and we will publish the report once complete.
Current landfill gas odour has been traced to cell 26D of Lower Compton Landfill site. We have asked Hills to provide us with a short to long-term action plan identifying how they will minimise odour and emissions from this area, and the likelihood of reoccurrence in future cells. We are currently discussing the scope and timescale of the actions required with Hills. However, actions already underway include:
• Change in material used as cover in the operational area from ‘trommel fines’ to soil. Work has been ongoing since 27 March to cover the operational area with soil, and we expect this work to be completed by early May.
• Ongoing review of temporary gas collection within the cell and installation of further gas collection wells.
• Ongoing monitoring to check the effectiveness of the cover
• Permanent capping of the current operational area.
Capping has been brought forward from July and will now start w/c 11th May. The work is expected to be completed within 13 weeks. Permanent capping and installation of permanent gas collection infrastructure is the best long-term solution to minimise odour and emissions. We are closely monitoring these works as they progress and are now undertaking weekly inspections of the site.
Further regulatory measures will be considered if improvements are not delivered at pace, these can include enforcement notices, restricting waste inputs, or other enforcement in line with the Environmental Permitting Regulations.
Partnership working at Calne
We recognise and acknowledge the impact the current odours are having on the community and are working closely with Wiltshire Council and the UK Health Security Agency (UKHSA) to identify specific odour sources and ensure action is taken to bring odour back to minimal levels.
What can I smell?
Odour pollution from landfill sites falls into two broad categories:
We are aware of symptoms reported within the community. These include reports of strong odours and transient health effects, such as eye and respiratory irritation. The human nose is very sensitive. Strong odours are unpleasant and can impact on wellbeing, leading to stress and anxiety. Some people may experience physical symptoms, such as nausea, headaches, or dizziness, as a reaction to strong odours, even when the substances that cause those odours are not at concentrations that are directly harmful to health.
What can I do to reduce my risk?
Individuals can close doors and windows whilst the smell is present and then open them to vent the smell from the premises when the smell has cleared.
Are the odours causing or going to cause any health effects?
The UKHSA (an executive agency of the Department of Health and Social Care) has been supporting the Environment Agency since April 2025, and as public health experts have fed into health related FAQ’s.
Strong smells are unpleasant and can impact wellbeing leading to stress and anxiety. Some people may experience short term symptoms such as nausea, headaches, or dizziness which although unpleasant are not harmful to human health. Exposure to low concentrations of hydrogen sulphide my cause the above symptoms at higher concentrations it may lead to discomfort and eye, nose, and throat irritation it may also disturb sleep.
What can I do to reduce symptoms caused by odour?
To limit the effects of odour as much as possible, we advise:
Contact NHS 111 or your GP if you have concerns about your individual circumstances and require health advice.
Why are symptoms sometimes more visible at night?
Landfill odours can sometimes be more apparent overnight due to changing atmospheric conditions, often linked to temperature inversions. During an inversion, a layer of colder air near the ground trap odorous gases. Preventing them from dispersing as effectively as they might during the day. Our officers conduct odour checks to ensure a true picture of the situation is being captured.
How does the Environment Agency decide a site is impacting the environment ?
The Environment Agency carefully monitors the performance of a landfill site using a wide range of parameters including groundwater, surface water and air monitoring, pollution reports and the operators own monitoring. We use all these parameters to determine the compliance of the site and if we have concerns, we require the operator of the site to take steps to resolve them.
Is air quality at and near the Lower Compton landfill site being monitored?
Yes. Our ambient air monitoring system installed in October 2025 along with readings from our officer’s handheld devices and the companies own data is constantly under review.
Report Odour
Please use our 24hr incident hotline 0800 80 70 60 to report odour you believe to be from activities we regulate. Although we are unable to provide feedback for individual reports, the information you provide will be used to inform our investigation and understand the scale of the impact.
Alternatively, reports can now be made online here: Report a smell from a waste facility, industrial site or farm in England - GOV.UK Please pass this briefing note to any other parties interested in the issues covered that you may be aware of. We will communicate further updates by briefing note when we have information to share. To be added to the circulation list please email: Wessex_Engagement@environment-agency.gov.uk .