Landfill Gas Monitoring Procedures

gas-monitoring-webLandfill gas monitoring to a correct procedure is important both for the advance warning of any underground migration of gas out of a landfill, and similarly for any development on the landfill affected by methane and associated gases. The following article should assist you in deciding where and what type of Landfill Gas Monitoring Procedures, you will need to apply to any given site.

In the case of landfill gas migration into the ground through a landfill lining, (and clearly this should not occur at modern containment landfills), the normal Landfill Gas Monitoring Procedure is that landfill gas monitoring boreholes are placed around the landfill perimeter at a short distance away from the landfill. The number and locations of landfill gas monitoring wells for migration detection and the monitoring frequency and sample analysis requirements are defined by the environmental regulator, under the environmental permit or for older landfills, within the landfill waste management license.


Landfill gas monitoring procedures normally require that sampling is done quarterly, monthly or more frequently at sensitive (elevated explosion risk) locations. Some landfill gas monitoring of houses and other buildings such as factories and shops is carried out continuously and coupled to alarms in the event of dangerous concentrations occurring.

Regular landfill gas monitoring and the adoption and maintenance of the correct Landfill Gas Monitoring Procedures is so important for any development affected by the risk of migration of methane and associated gases. It is required not only at the investigation and design stage of a development project but also during construction and subsequently in the long term.

Official Guidance on Landfill Gas Monitoring Procedures

The book “Protecting Development from Methane”; CIRIA Report 149, London 1995, makes a series of recommendations about good practice in landfill gas monitoring procedures. We recommend that any reader involved in a  project of this sort or considering one should obtain (via their own educational establishment’s library or by purchase) a copy of CIRIA Report 149. It is available from the IHS web site here.

The following is based upon the above publication. You may use it to consider the extent to which landfill gas monitoring will be needed for your project or development if it is near or located on a landfill, but if in any doubt, or if intending to make a decision, you must either buy and use the relevant documents, or employ an expert.

Nobody should be in any doubt about the seriousness of a landfill gas incident let alone an explosion. Gas accidents are particularly serious and usually with gas accidents you won’t get a second chance to get it right without injury occurring first, so adopting landfill gas monitoring procedures which comply with good practice guidance just makes good sense.

The landfill gas monitoring carried out may need to establish:

•      gas composition

•      gas concentration

•      gas emission rates

•      variations with time and meteorological condition.

With the following potential further monitoring needs:

￿ To monitor change in gas regime

￿ To ensure safe working conditions.

￿ To check that protection measures are working

￿ To give early warning of a hazardous situation.

You may also need to consider:

￿ Any off-site investigation needed affecting adjacent development

￿ Doing the monitoring over not less than 3 and preferably more than 6 months before concluding

￿ Monitoring throughout the construction period

￿ Continuing landfill gas monitoring all the time, or just at periodic intervals after construction.

Note: The frequency of taking measurements depends on the situation and the information needed, ranging from near-continuous observations to readings at intervals of weeks.

The extent of gas monitoring to a defined set of landfill gas monitoring procedures required at each stage of development will depend on the nature of the gas regime, the quality and reliability of the monitoring data obtained and the scope of protection measures adopted.

Gas monitoring by using a set of landfill gas monitoring procedures may also be used to safeguard the occupants of existing real estate developments potentially affected by gas.

Alarm systems are an extension to gas monitoring. They provide an audible or visual warning when gas concentrations exceed pre-set criteria when specific action is required. The alarm system may be integral with the gas monitoring device or remotely connected by telemetric link or other signalling devices to a control centre.

Gas Monitoring and Alarms

Gas monitoring is important for any development affected by methane and associated gases. It is required not only at the investigation and design stage of a development project but also during construction and subsequently in the long term.

Gas monitoring requirements during development Phase of development has the combined purposes of:

￿ Duration

￿ Feasibility

￿ Monitoring unlikely except as preliminary spiking survey if visual or documented evidence is found.

￿ Site investigation

￿ Construction

￿ Post-construction and long term

To establish:

•       gas composition

•      gas concentration

•      gas emission rates

•      variations with time and meteorological condition.

The purpose of landfill gas monitoring is:

    • To monitor change in gas regime
    • To ensure safe working conditions.
    • To check that protection measures are working
    • To give early warning of a hazardous situation
    • To check that there is an off-site investigation affecting adjacent development
    • Over not less than 3 and preferably more than 6 months
    • Throughout construction period
    • Continuing or at periodic intervals.

The frequency of taking measurements depends on the situation and the information needed, ranging from near-continuous observations to readings at intervals of weeks.

The extent of gas monitoring required at each stage of development will depend on the nature of the gas regime, the quality and reliability of the monitoring data obtained and the scope of protection measures adopted. Gas monitoring can also be used to safeguard the occupants of existing housing and factory development potentially affected by gas.

Alarm systems are an extension to gas monitoring. They provide an audible or visual warning when gas concentrations exceed pre-set criteria when specific action is required. The alarm system may be integral with the gas monitoring device or remotely connected by telemetric link or other signalling devices to a control centre.



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