Odour Response in Calne

Odour Update 22 June 2026: Lower Compton Landfill Site, Calne

Over the weekend, we received over 100 reports of odour. We have had staff out proactively monitoring throughout the weekend to corroborate reports.

We continue to ensure that Hills carries out improvement works to the Lower Compton landfill site to the standard we expect. Good progress has been made with the capping works, with the subsoil restoration layer now spread over approximately 60% of the permanent capping to protect the clay. Once the works are complete, we expect odour levels to improve, and we will carry out extra odour monitoring to assess the change in levels.

On modern landfills, engineering work is carried out under a Construction Quality Assurance (CQA) plan, which has to be accepted by the Environment Agency prior to work being started. Information about CQA for landfills can be found here: Landfill operators: environmental permits - Construction quality assurance (CQA) - Guidance - GOV.UK

Inspections of the construction work include:

• Assessment of field testing and lab sample results to confirm the clay used is within specification.
• Site walkovers to check for any non-conforming material (such as large rocks) and to confirm the works are being carried out as per the approved CQA plan.
• Reviewing the CQA Inspectors records and ensuring the work has the required level of supervision.

Where work has not met the required standard, or where fugitive emissions have been identified, we have required the contractor to rectify and repeat the work.

Residents may be aware that earlier this week there was a fire at a neighbouring recycling centre. This was unrelated to the permanent capping works at Lower Compton Landfill and has not affected or delayed the remedial works.

Environment Agency staff monitoring at the Lower Compton siteMonitoring

In recent weeks, we have shared information on how we are monitoring odour and air quality (see: https://engageenvironmentagency.uk.engagementhq.com/wessex-regulated-industry-sites/news_feed/odour-response-in-calne).

We have a monitoring facility at Priestley Primary School. A range of factors were considered when selecting the monitoring location. The monitoring facility has been positioned to reflect:

• The likely route that hydrogen sulphide would travel into the town; odours can move along valleys at night due to cooler, denser air
• Residential areas where high numbers of odour reports have been received on the eastern side of Calne, ensuring monitoring reflects areas of highest concern
• The prevailing wind direction, local topography, and the need for suitable hard standing and a mains power supply

The Mobile Monitoring Facility (MMF) measures ambient air quality in the area, which may include emissions from multiple local sources. As well as methane and hydrogen sulphide levels, we also record meteorological conditions, including wind direction, wind speed, temperature, and atmospheric pressure.

The data collected from the MMF has now been sent to the UKHSA to allow them to make an independent health impact assessment.

Annotated photograph of an MMF exterior