The Environment Agency has said odour controls at the Lower Compton landfill site are “not performing as expected” and are currently inadequate, following a surge in complaints from residents in Calne.
In an update issued yesterday, the Environment Agency said reports of odour have risen sharply in 2026 - with over 1,000 complaints recorded in March and a further 726 in April to date.
It said odour in residential areas has been identified and traced to the site, with the main source identified as the current open landfill cell, known as Cell 26D, operated by Hills Waste Solutions.
The Environment Agency said: “Our position is clear: odour impacts at this level are not acceptable, and the operator must act quickly to resolve the issues.”
It added that regulatory measures including restricting waste inputs or taking enforcement action, may be considered if improvements are not delivered.
The regulator confirmed it has required Hills to produce a short and long-term action plan to reduce odour and prevent a recurrence.
According to the Environment Agency, actions already underway include switching landfill cover material from trommel fines to soil, installing additional gas collection wells, and ongoing monitoring to assess effectiveness.
Permanent capping of the operational landfill area has also been brought forward, with work expected to begin in early May and take approximately 13 weeks, subject to conditions.
The Environment Agency said it is now carrying out weekly inspections of the site and continuing odour monitoring in the community, including during early mornings and evenings when odours are most commonly reported.
The update comes as Hills issued further clarification after residents submitted a series of questions to Calne Town Council amid ongoing concerns.
In its response, the company addressed issues including health impacts, waste types and how odours are being managed.
On health concerns, Hills referred to previous Environment Agency guidance which includes input from the UK Health Security Agency.
That advice states that while odours can cause symptoms such as headaches, nausea and irritation, measured levels of hydrogen sulphide in residential areas were below those where harmful health effects would be expected, with the overall risk to public health considered low.
However, the same advice also states it is “not possible to entirely rule out” risks due to uncertainties around exposure levels.
Residents experiencing persistent symptoms are advised to seek medical advice via NHS services.
Hills said the smell may be linked in part to “trommel fines”, a type of waste material it has now permanently stopped using at the site.
The company said these materials can contain sulphates which, under certain conditions, may produce hydrogen sulphide - a gas commonly associated with a “rotten egg” smell.
Separately, the Environment Agency said the initial increase in odour complaints earlier this year was likely linked to the installation of additional gas collection wells, which involved disturbing recently deposited waste. However, complaints have continued since that work was completed in February.
The Environment Agency said it has carried out multiple odour inspections in recent weeks and continues to monitor air quality in Calne using an on-site station measuring hydrogen sulphide, methane and particulates.
Data from this monitoring will be reviewed by the UK Health Security Agency, with updated public health advice expected once validation is complete.
The regulator said it will continue to assess whether actions taken by Hills are effective and will take further steps if required.
Residents are encouraged to report odour incidents via the Environment Agency’s 24-hour hotline or online reporting system to support the ongoing investigation.
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