The Difference Between Category One and Two Landfill Gas Analysers
The Dangers of Hazardous Landfill Gas
Over the lifetime of a landfill, bacteria degrade the waste and produce hazardous gases. Such gases can be harmful for workers on site and nearby properties, and monitoring is hence mandated by the Environment Protection Authority (EPA) in Australia. The Best Practice Environmental Management; Siting, Design, Operation and Rehabilitation of Landfills guideline specifies the exact levels of gas considered safe that must be maintained. It also highlights key factors that can affect gas composition including the landfill’s layout, age, types of waste accepted, rainfall and more.
Harmful gases include methane (CH4) and carbon dioxide (CO2), the former of which is known for being flammable and extremely dangerous at high concentrations. Exposure to low concentrations, however, will not generally cause harm. Methane is colourless and odourless, meaning that it cannot be detected without the proper equipment. In 1902, a lack of awareness led to the deaths of 94 miners from a methane explosion at Mt. Kembla Colliery. Even after this devastating event, plenty more accidents followed before proper regulation was organised and implemented. In the modern day, vastly improved practices have massively reduced the risk of such events recurring, and gas monitoring has become a vital step in creating a safer environment for workers and the community.
Other gases present at a landfill include nitrogen (N2), oxygen (O2) and trace gases. Oxygen can be hazardous as it can be displaced by the presence of other gases, potentially leading to asphyxiation; a lack of oxygen that can render workers unconscious. Depending on the types of gas present, chronic, long terms health issues are also a possibility. It is important to limit the exposure of workers to these conditions while the landfill is active and ensure that monitoring continues after closure to protect nearby communities and the environment.
Types of Landfill Gas Analysers
There are two main categories for instruments used to analyse harmful gases in landfill:
Category 1: Extractive Landfill Gas Analysers
Instruments under this category, such as the IECEx certified GA5000 Landfill Gas Analysers, are designed specifically for analysing landfill gas. They measure volumetric concentrations (% v/v) of methane, carbon dioxide, oxygen and some trace gases. They also measure bore relative pressure (mb or hPa) and gas flow (L/Hr). These can be used for risk analysis, helping to maintain the safety of workers and nearby property.
Category 2: Low-Concentration Methane Detectors
There are two kinds of gas detectors that are classed under low-concentration methane detectors; flame ionisation detectors (FID) and laser spectrometers. Flame ionisation detectors measure a variety of gases and volatile organic compounds (VOCs) and are not exclusive to methane in terms of flammable gases detected. Typically, methane will comprise 98-99% of the flammable component of landfill gas, and FIDs are hence acceptable for use monitoring the surface of a landfill when calibrated with methane.
The second type of methane gas detector is the laser spectrometer. Methane detectors such as the Inspectra Laser Portable Leak Detector are designed to use the wavelength of infrared light absorbed by methane to measure emissions over the surface of a site.
Selecting a Suitable Landfill Gas Analyser
Portable gas analysers are excellent for monitoring worker safety, with most analysers designed to be easy to use and calibrate. Portable gas analysers such as the category 1 GA5000 Landfill Gas Analyser are ideal for spot readings and are commonly used for landfill gas monitoring bores, onsite investigations and gas risk assessments. Category 2 analysers including the Inspectra Laser Portable Leak Detector are suitable for monitoring the surface of a landfill, subsurface services, buildings and other similar applications. These detectors are suitable if methane is the only concern. As it focuses solely on methane, these gas detectors are useful when there are other flammable gases present. Devices such as FIDs cannot differentiate between methane and other detectable gases, meaning that it could potentially return a positive reading even when there is no methane present.
Landfills need to be monitored over extensive periods to reduce their impact on the environment even after they are no longer active. Over longer distances and time periods, portable options can become labour intensive, making them less preferrable. Permanent bore systems are designed to be used for continuous, unmanned monitoring. The Ion Science GasClam 2 Gas Monitor is reliable for abiding with environmental protection regulations, and unlike many other devices, records other parameters known to affect ground gas and therefore provides greater visibility into the landscape of the landfill. Such options help ensure that gas concentration levels are always monitored and therefore reducing risks to workers and the community.
Landfill gas monitors are available from Air-Met Scientific for sale and rental. To learn more about what landfill gas analyser is most suitable for your monitoring needs, contact your local Air-Met Scientific representative today!
