Case study: Monitoring gas at a landfill site
Hartlebury Landfill occupies an area of 8.3 hectares. The site was originally quarried for clay and this was used for brick making as far back as the early 1900’s. The site was first landfilled by the then Hereford and Worcester County Council in 1984 and accepted domestic and non-hazardous commercial waste. It ceased operating in April 1991 and is now filled with approximately 723 200m3 of waste with an average depth of 10m.
Chris Dakin, Gas Data’s technical director, says:
“The disposal of large quantities of organic waste in land voids leads to a natural process of degradation caused by the bacteria contained within it. In particular, bacteria that thrive on the oxygen-depleted conditions found deep within waste convert the material from solid or liquid form to a mix of gases containing approximately 60% methane and 40% carbon dioxide – plus significant quantities of water.
Historically this process was largely ignored and the gases produced simply escaped into the air. However, methane is highly flammable and can be detrimental to plant growth, so in the late 1970’s these dangers and environmental hazards were finally recognised leading to environmental laws and regulations. Today’s waste disposal sites are highly organised and engineered.”
Last year, the gas control system at Hartlebury was updated with new internal wells and pipework. The control system comprises fifty-one internal wells linked to a flare stack that burns off the landfill gas in a controlled manner, this ensures that the potential for gas migration is kept to a minimum. The flare has a Gas Data Click! System installed to monitor the gas from the landfill.
The Pollution Control Manager at Worcestershire County Council says:
“Landfill Gas is produced from the decomposition of waste and the site can become pressurised, we can control the gas by pulling it towards the gas compound and flaring it to atmosphere, this reduces the potential of gas migration off site where it could impact on the local environment.
The Click! System enables us to log on from the office – or from a lap top – and see the gas concentrations at the flare. The gases we measure are methane, oxygen and carbon dioxide. Landfill gas concentrations will vary depending on the type and age of the waste.”
Check the Click! System on line gas analyser web page if you want more product details or call us on +44 (0) 2476 30 33 11 today.