Landfill monitoring and data interpretation

Landfill monitoring and data interpretation

Project title:        Landfill monitoring and data interpretation

Client:                  Argyll and Bute Council

Location:             Isle of Mull & Isle of Islay


Determine whether methane encountered at the site perimeters is the result of migrating landfill gas or naturally occurring methane in peat deposits.

Services performed by GGS:        

  1. Periodic ground gas monitoring of former and active landfill sites
  2. Ground gas sampling and third-party laboratory analysis
  3. Data management
  4. Data interpretation
  5. Consultancy

Landfill monitoring and data interpretation



GGS was asked by a client to assess the presence of methane at a local recycling centre located at an active landfill site. The site included several old landfill cells that have been decommissioned and capped. From data acquired through previous monthly periodic monitoring, the client had evidence that gas from the landfill site could be breaching the perimeters. The data had also shown an increase in methane concentration over time in certain monitoring wells. The two sites contain peat rich soils which naturally produce methane. Therefore the client required a review to investigate whether the methane recorded at the perimeter of the site was naturally occurring or if it was migratory gas produced form the nearby landfill.


Prior to attending site, GGS carried out a review of periodic monitoring data provided by the client for the site from the last 10 years. This data was inputted into a spreadsheet to create ternary plots for each monitoring well at each site to help visually establish the ratios of gas and to help determine whether it is landfill gas, soil gas, atmospheric air, or migrating gas. After comparing the historic data, it appeared that the perimeter monitoring wells were exhibiting ratios comparable to that of typical soil gas. The monitoring wells inside the waste were exhibiting ratios comparable to that of typical landfill gas – which was all good news.

For further clarification, the gas composition needed to be established at two sites. Therefore, two gas samples were taken at the Isle of Mull site and two samples were taken at the Isle of Islay site. GGS initially carried out periodic monitoring at each location of all available monitoring wells, including those in the waste and those at the perimeter.  Following periodic monitoring, it was found that results agreed with previous monitoring data provided by the client; a monitoring well on each site perimeter was exhibiting an elevated concentration of methane. As expected, monitoring wells within the waste were exhibiting classic levels of landfill gas.

Two sets of foil coated Tedlar Bags were filled by pumping gas directly from the monitoring wells at each site; from monitoring wells located inside the waste and at the perimeter. These were then sent to the laboratory to more accurately establish the concentrations of gases present. The laboratory carried out a Standard Landfill Gas Suite on each sample which included testing for gases associated with landfill such as bulk gases (methane, carbon dioxide, nitrogen etc.), arsenic, aldehydes and VOCs.


  • GGS is a one stop shop for ground gas characterisation and data interpretation
  • Our comprehensive suite of services mean you can access a package tailored to your site that delivers exactly what you need
  • We cover ground gas in all forms of contaminated land, including landfill and brownfield sites
  • Our experts can interpret and apply data taken by third parties to help you find a solution
  • We combine safe deployment of equipment with reliable data acquisition to deliver accurate results to our customers
  • Customers have access to cost-effective solutions through our complete selection of services
  • Our fleet covers the whole of the UK


Hundreds of consultants and regulators rely on us for consistent and accurate ground gas monitoring and data services.

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For more information on our continuous monitoring data management services, click here.