In March 1986 a house at Loscoe in Derbyshire was completely destroyed by a landfill methane explosion, badly injuring the three occupants inside the home.
A Public Inquiry was carried out on the the series of events leading up to the incident and evidence was produced to ascertain the origin of the methane.
Through the inquiry it became apparent that signs of ground heating had been detected approximately 100m beyond the boundary of a near-by landfill some years before the explosion but that the phenomenon had been misinterpreted as a shallow burning coal seam.
It’s possible that had the investigators identified the landfill as the source of the methane at that time the Loscoe area would have been protected from the dangers of uncontrolled gas migration.
AVADA Environmental looks into what exactly what went wrong at the Loscoe landfill all those years ago, and analyses the regulations that have been put in place in the aftermath to prevent a repeat incident from occurring.
Loscoe Methane Explosion
At the Loscoe landfill there were no system failures, but rather a failure to appreciate the risks from landfill gas and the need for methane extraction and flaring. On the day of the incident, Loscoe experienced the lowest day of barometric pressure for 25 years.
This had the effect of allowing the methane, which had been unknowingly building up in the landfill, to rise and find a method of escape through disused mining channels that ran beneath the site and led directly to a residential housing estate nearby.
The gas found its way into cellar voids beneath the properties and, when the early morning pilot light came on for the central heating beneath the bungalow in question, the resulting explosion became inevitable. Thankfully the residents escaped alive, but their property was destroyed. The housing estate was evacuated immediately and 55 households were placed in temporary accommodation until the area could be made safe.
Investigations showed that there was a substantive build-up of methane under the estate which had been effectively piped under the properties by mining channels from the landfill nearby. This was the first time that the regulatory authorities realised that infilling organic matter had the potential to generate large quantities of methane.
Following the Loscoe incident, best practice was changed to require venting and flaring of landfill sites capable of methane generation and also to require sites to be lined to prevent leaching.
This is as well as requiring them to be monitored to assess and prevent unauthorised methane escapes. After Loscoe, a series of alarms and other safety measures were introduced to enable site operators to monitor their operations and to prevent escapes outside site boundaries.
Regulation Changes
Since the Loscoe incident the regulatory landscape has changed significantly. The regulation of UK landfilling operations is now in the hands of the Environment Agency, Scottish Environmental Protection Agency (SEPA) and the Northern Ireland Environmental Agency (NIEA), and all waste operations are now controlled by one Environmental Permit. There is now a clear regulatory framework in place.
The first prosecution under this framework occurred in 2011 when Waste Recycling Group Central Limited was ordered to pay £28,184 for committing two offences under the Environmental Permitting Regulations 2007.
Waste Recycling Group Incident
The offences related to WRG’s management of a closed landfill site in Berkshire that contained local household and business waste, buried under restoration soils and a clay cap. The site was regulated under the terms of an environmental permit issued by the Environment Agency (EA). This required WRG to ensure a system was in place and was regularly monitored to ensure the capture of potentially harmful landfill gas.
The system implemented by WRG extracted gas out of the site and pumped it to a flare which burned the gas and converted it to carbon dioxide. An alarm system was activated if there was a fault with the flare to allow an emergency plan to be put into place.
In May 2008, on-site works resulted in the power supply to the site being cut off for a period of up to two days. The power cut affected the functioning of the gas flame alarm system. No back-up or replacement alarms had been installed so the loss of the gas flare meant no methane gas extraction took place across the landfill, resulting in the escape of gas in several directions as well as the risk of it escaping into the atmosphere.
When the power was switched back on, WRG discovered that many perimeter boreholes had exceeded the permitted levels for methane and carbon dioxide. WRG took steps to rectify the situation including notifying the EA and undertaking extensive gas monitoring. A review of its management procedures was also conducted.
Following notification of the incident, the EA prosecuted WRG for:
- Failing to comply with its environmental permit by exceeding the allowed limits of landfill gas and CO2.
- Failing to follow the site management system for the site between January and June 2008.
The magistrates’ court hearing the case noted WRG’s co-operation with the EA, lack of financial gain and early guilty plea as mitigating factors in sentencing. However, it emphasised that it takes environmental offences very seriously and that WRG, as a large professional waste company, “should have known its own business”.
Conclusion
At Loscoe, the incident occurred as a result of a lack of understanding of the process operations and necessary controls and, as such, the explosion could be seen as a direct consequence of the landfill operation.
It is ironic for WRG that its site in Berkshire was being actively managed and controlled until works unconnected with the landfill operation meant that power was cut to the site, thus effectively removing its safety alarm systems.
It was clear that no proper risk assessment had been carried out either of the alarm systems themselves or of the proposed works and its ability to impact the site management system at the landfill.
The fines in the WRG case may not have been significant, but it’s clear the court considered WRG’s swift and open response to its failures, which mitigated the penalty. The fines could have been much higher and it is clear that the strict regulatory regime is in place to serve as a deterrent and to remind operators of their strict responsibilities. If the recent case had led to substantive environmental damage or harm to human health, the penalties would have been much higher.
When both cases are brought into contrast it’s clear to see how not just how the authority’s approach on the dangers of landfill waste has evolved but also how the general awareness on the potential consequences of infilling organic matter has improved and the importance of methane extraction and flaring has grown.