Ground Gas Risk: Loscoe & Landfill Management
In 1986, a bungalow in Derbyshire was completely destroyed by a landfill methane explosion, badly injuring the three occupants inside the home. This now famous and near-tragic incident served as a low-water mark in landfill management practices and site investigation.
We look back at the explosion, what was learnt and summarise the improvements in identifying and managing ground gas impacts to property from nearby landfills and old mines.
Background to the Explosion
The village of Loscoe, near Heanor, Derbyshire is an area with a rich coal mining history. But in March 1986 an explosion occurred that changed the UK’s approach to landfill regulations.
The incident was a long time in the making. Initially the site was a brickworks dating from the mid-nineteenth century and operational until the early 1970s. The quarry that supplied the clay was part-filled with inert waste products from the brick-making which ceased in 1971. Filling continued with permission granted for the tipping of inert materials only by other companies through to 1978, when one of the companies purchased the site. Prior to this in 1977, a licence had been granted to tip a wide variety of wastes, including 50 tons per day of untreated domestic waste.
It took 7 years for the first signs of ground gas generation to become apparent: Lawns started to show crack-lines of dead dried-grass, and trees began to wilt and die in the surrounding gardens. The soil around the affected areas began to heat up, which was thought to have been due to the presence of methane feeding bacteria. What was not observed was the increasing concentrations in the ground of methane, carbon dioxide and carbon monoxide.
Despite objections from residents living in nearby houses, which by the end of the 1970s surrounded the quarry infill on all four sides, authorities granted extensions to increase the quantities of domestic waste being dumped. As a result, residents had to endure increasing numbers of vermin and flies.
As organic matter decays, it produces methane alongside carbon dioxide. The explosion’s origins can be traced to two main causes: a fundamental lack of understanding of methane management, which led to a negligent “out of sight, out of mind” approach, and the absence of an engineered escape route for the gas, which created the perfect conditions for the explosion.
Explosion, Evacuation and Inquiry
Image courtesy of British Geological Survey
Early on 26 March 1986 51 Clarke Avenue exploded. It completely demolished the bungalow and it was a miracle that the three residents escaped with their lives.
The resulting investigation showed two more houses had technically been unfit for habitation for the preceding nine months. The estate was immediately evacuated and 55 households were placed in temporary accommodation until the area could be made safe.
A Public Inquiry was carried out on the events leading up to the incident considering a range of possible sources of the gas causing the explosion; natural gas supplied for heating, the underlying coal measures and last, and very much least, the nearby landfill site.
Once the landfill was identified as the source a number of factors combined to create the conditions for the explosion (Ryan et al, 1988)
- Accumulation of an appreciable quantity of landfill gas (tens of cubic feet) in an old well or other void in the ground close to the bungalow;
- Expansion of the landfill gas in response to a large drop in barometric pressure;
- Flow of the expanding gas along the backfill to a drain into the floor space below the house; and
- Ignition from a central heating boiler.
A further feature of that day that has become a major discussion point in current assessment, although no longer thought to be material to this explosion is the low pressure, is the rapid drop in barometric pressure over 7 hours to the lowest pressure recorded for 25 years of 29 millibars.
The investigations proved to be a “Eureka moment” for the regulatory authorities and, for the first time, they recognised the hazard potential for large quantities of methane gas being generated by landfilled organic matter. It coincided with the Control of Pollution Act (CoPA, 1974) with early versions of landfill regulation and the Waste Management Paper 26 – Technical Guidance (1986) which set out research into the way landfills behaved and could be managed.
Tightening Regulation
Since the Loscoe incident, the regulatory and site investigation landscape has also changed significantly.
Site operators were initially required to implement a series of alarms and other safety measures to enable site operators to monitor their operations and to prevent escapes outside site boundaries. Since The Waste Management Regulations (1996), regulations have developed with tighter control of waste inputs and also of site closure and surrender processes to allow permits to be returned to the regulator because they are no longer deemed to pose an environmental risk. UK landfilling operations are now regulated by the Environment Agency (EA), Scottish Environmental Protection Agency (SEPA), the Northern Ireland Environmental Agency (NIEA) and more recently Natural Resources Wales (NRW).
Since 2016, landfilling has been controlled under the Environmental Permitting Regulations 2016, supported by a clear regulatory framework.
The implications of this are that over time landfills have been subject to increasing regulation. This means that older landfills were less regulated, less understood and more likely to pose a risk to those owning the site as a result of what it contains and what it might generate. It is only in 1996 that sites could be formally surrendered back to the Regulator, so any landfill that did not qualify for a Waste Management Licence is something of an unknown quantity.
Another perspective on landfills is development. This is an area of active debate currently as concern about gas generation has resulted in gas control measures being installed ‘just in case’. At first glance this may seem prudent, as the measures are generally cheap and can be seen as an upgraded damp proof course. However, in order to be genuinely effective, any gas protection measures must be well installed, sealed and verified. A badly installed gas membrane is ineffective, may not be compliant with planning conditions and brings with it a false sense of security. To support this a new scheme to become an Accredited Person to install gas membranes is calling for applicants now.
Many of the gas assessment and monitoring processes used have their origins in the Loscoe disaster. Considerations in the initial modelling include coal seams and mining features that can impact the flow of gas through the subsurface, continuous gas monitoring or at least ongoing event monitoring to establish gas flow rate in situations where barometric pressure is dropping. These will be delivered through Coal Mining Risk Assessments and as part of the Planning process.
Recognising Potential Contaminative Risks and Liabilities
So it is clear that risks from landfill ground gas are now better understood and there is far greater rigour applied now to oversight and operational management.
According to Defra in 2019, there were some 325,000 potentially contaminative sites across the UK, of which just 11% have been brought to the attention of Local Authorities to maintain their contaminated land registers on just 11,000 of those sites. Historic landfill records are also very inconsistent, with little information on what went into former quarries in the 1970s and 1980s – two of our most environmentally polluting decades.
Many housing estates built well into the 1990s have been developed around former landfills that were infilled before better regulations came in just after 2000. The risk of ground gas emergence and contaminative leachate affecting groundwater abstractions used for drinking water can remain a threat, as their histories are largely unknown.
And where risks are known and proactive management is taking place, homeowners and businesses have to accept gas flaring or other treatment happening in close proximity.
With the benefit of hindsight, it is clearly a monumental error of judgement to surface tip contaminated waste into quarry voids in an unregulated manner. Much of this was a simple reaction to the rapid acceleration of disposable products from the 1960s onwards, but also the fact that much of the waste contained high proportions of organic compounds which caused more harmful leachates and gases as they decayed.
Fortunately, we now have a thriving recycling sector, with many Local Authority Waste Management sites recording recycling to avoid landfill in the high 90th percentile or better, as our attitudes to reuse and recycling have changed.
Recognising that your client’s property asset could be in close proximity to historic, unregulated infilled quarries and dumps is an important part of risk due diligence. There could be significant contaminative health risks and potential transfer of liabilities as the original polluter is highly likely to have ceased trading.
It is important for commercial real estate lawyers to provide an early indication of risks from potential contamination for their client, whether they are acquiring a site for development or reviewing past land use for existing property and any residual liabilities. Our Review Report provides clear insight on the site history and indicates if the property is in close proximity to potentially contaminated land. Backed by our large, expert team of environmental consultants who forensically analyse the data to provide clear guidance for your client to make confident decisions going forward.
For more information on our commercial environmental searches, call us on 01273 257 755 or email info@groundsure.com
References
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Date:
Aug 2, 2024
Author:
Ceri Sansom