The risk of fires at large waste sites has been a cause of concern for many years — but why can piles of waste spontaneously combust?

Biological decomposition can create substantial heat and it is thought the fire at the former Hunters Group tip site in Lockwood may have started as a result of a build up of heat within the composted waste which includes shredded plastic, wood and paper.

In many cases, where there is a large stack of waste, a fire can start very deep down. With very little oxygen to fan the flames, the smouldering can go unnoticed for many days before smoke then starts to be seen.

It is often hard to reach the seat of the fire, with large amounts of waste having to be moved first.

Video thumbnail, Smoking waste excavated at Lockwood site
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And this can lead to the risk of flames shooting into the air as more oxygen then reaches the fire.

Firefighters acted fast at the Lockwood site, off Queen's Mill Road, to prevent a repeat of the fire at a waste site in Scout Hill in 2010 which took over a month to dampen down.

Crews were called to the smouldering Hinchcliffe Bros Scout Hill Waste Transfer Facility on February 7. The site was functioning well above its permitted waste levels and the clean-up operation at the site flushed out a number of rats which were reported in the surrounding area.

Fire at Hinchcliffe Brothers Ravenswharfe Road Scout Hill in February 2010

Typically three fire engines and an aerial appliance attended the site every day, tying up hundreds of thousands of pounds worth of equipment and creating an arduous work environment.

In recognition of the growing concern waste tip fires are causing, the Chief Fire Officers Association organised a Fire Futures Forum in 2013, with stakeholders from the waste industry, Government, Environment Agency and insurance sector, looking to identify potential solutions that would reduce the number and severity of fires at waste management and recycling centres, or where they did occur, to mitigate their impact.

At Lockwood, specialist equipment will be used to try to get to the seat of a fire which may have been smouldering at the controversial Huddersfield waste tip for weeks.