Landfill fires: What you need to know

Following several blazes at the George Town Landfill this year, there was a lot of speculation about how landfill fires start, the steps that can be taken to prevent or extinguish them, and how remediation can reduce the risk of future incidents.

Although landfill surface fires normally have fairly obvious sources of ignition — such as lightning, burning or smouldering waste being added to the mound or a stray spark from machinery — the origins of deep-seated fires are more mysterious.

Department of Environmental Health Director Richard Simms says that landfill fires often start below the surface.

“Although some hot spots are created through the burial of hot waste or easily combustible waste, the natural decomposition process can also generate a lot of heat,” he says. “If the hot spot becomes exposed to oxygen or an ignition trigger, it can cause a fire.”

Constant monitoring 

Simms says that both his department and the Cayman Islands Fire Service underwent training earlier in the year on strategic waste management to prevent fires and firefighting tactics to effectively control and extinguish any future blazes.

“Thousands of landfill fires occur around the world every year,” Simms says. “Covering the waste routinely to prevent oxygen infiltration and monitoring the waste for signs of deep-seated fires are essential. If a fire does occur, the Fire Service focus on control until there is no open flame or minimal smoke, and then they can implement site-specific extinguishment measures such as covering or injecting water.”

Remediation 

Once complete, remediation will significantly reduce the risk of fires at the George Town Landfill. By covering exposed garbage and preventing oxygen infiltration, the cap will effectively seal off the surface of the waste mound.

“Without oxygen, the landfill gas generated through decomposition of waste will not sustain fires,” Simms explains. “The cap will starve the mound from oxygen and a gas collection system will draw the landfill gas – which is predominantly methane and carbon dioxide – out of the capped site. The landfill gas will initially be safely flared off and then will be piped over to the new waste-to-energy facility to be used as a supplemental fuel.”

Remediation of the landfill includes covering or capping the mound of waste with a layer of fill material similar to marl, then a barrier of man-made liner, followed by more fill and then a layer of topsoil to support the growth of grasses and shrubs. Remediation is expected to be substantially completed in about 18 to 24 months with the exception of about 5 acres where waste will be placed until the waste-to-energy facility is in operation.

Through a combination of eight integrated facilities, the country’s new solid waste management system will reduce the amount of waste going to landfill by up to 95%.

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This article appears in print in the August 2020 edition of Camana Bay Times.

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