Updated guidance on the prevention of fires at waste management sites – including ‘firmer science’ on waste stack separation distances – has been published by the Waste Industry Safety & Health (WISH) Forum.
The guidance, which is updated from an initial version published in October 2014, takes into account the findings of ‘waste burn trials’ carried out in 2015 and 2016 to test the properties of waste materials including wood, plastic, paper, rubber and waste derived fuels when set alight. For the earlier guidance: see letsrecycle.com story.
According to WISH, an industry body comprising health and safety experts from a number of UK waste businesses, the findings of the trials have led to a revision in the recommended stack size and separation distances originally set out for wastes stored externally.
One of WISH’s initial fire tests on baled material, which took place in 2014 at the Fire Protection Association in Gloucestershire (photo: WRA)
In the 2014 document, WISH had advised a 5 metre maximum stack height for waste stored in a loose stack, as well as a 4 metre maximum for baled material.
However, the updated guidance revises this recommendation for waste materials including wood and paper, which will burn at a temperature of up to 950°C– down to 4 metres for the material if it is stored in a loose stack.
4 metres height
The new guidance also maintains that baled stacks must be no more than 4 metres tall, but with an added stipulation that stacks should contain a maximum of four bales.
Chris Jones, chair of the WISH Forum, said: “We have made tremendous progress since 2014 when we published the last guidance and this latest guidance is literally groundbreaking and attracting interest from across Europe. We know things now which we didn’t know then as there was an absence of data about how waste burns. No-one had carried out any scientific work on burning waste, the research had been derived from raw material burns.”
Mr Jones added: “Stack sizes are an important part of the guidance. Four metres high is pragmatic in terms of safety and a 20m width allows the fire brigade to effectively reach the bales. Unlike the Agency, we consider that length doesn’t really matter as long as it can be reached. You could even have the bales snaking up and down to increase the storage area.”
The WISH chair said that plastics have been identified as a particularly problematic material as the heat generated in a fire is considerably more than for paper, card, RDF and mixed waste, burning at 1200 deg C or more rather than 950C for the other materials.
“The fire service have been really helpful, saying let’s get in and fix this problem.”
Chris Jones
Wish Forum
He noted: “It is not really a very good idea to store large volumes of plastics in the outdoors and we would recommend thermal barriers to stop the heat penetration in a fire.”
And, Mr Jones thanked the fire service for its support in drawing up the guidance. “The fire service have been really helpful, saying ‘let’s get in and fix this problem’.”
Practical
WISH claims that the latest recommendation is based on the practical ability to fight fires using manual means such as standard hoses and stability of bale stack to reduce the risk of fire spread from falling bales.
On separation of stacks, the 2014 WISH guidance had initially recommended a separation distance of 20 metres for materials which are not separated by a firewall.
In the latest guidance, WISH has developed a graph to determine separation distances based on stack width or length. This suggests that loose stacks measuring 5 metres should maintain a 5 metre gap, whilst material stored in a stack measuring up to 50 metres should maintain a gap of up to 12 metres.
For baled material the recommendations are stricter still, with a 5 metre bale stack requiring a 9 metre separation distance, and a 50 metre stack requiring a gap of up to 23 metres in length.
Plastics and rubber have been listed separately as they typically burn at a higher temperature of up to 1,200°C. Loose plastics stacks must be stored at a distance of 11 metres where the stack is 5 metres in width, and 31 metres where the loose stack is 50 metres wide.
Baled plastic material must be stored 14 metres apart where the stack measures 5 metres, or up to 40 metres apart for a 50 metre wide stack.
The guidance, which has been developed with the support of the Chartered Institution of Wastes Management, Environmental Services Association, and Chief Fire Officers Association is intended to reduce the likelihood and frequency of fires at waste sites, as well as reducing the potential health and safety risks where fires do occur.
One of the large fires in recent years was at the Jayplas site in the Midlands which was started by a Chinese lantern. Now, there is advice about the storage of plastics which burn at high temperatures
WISH’s recommendations differ from the standard fire prevention measures set out by the Environment Agency, as a requirement of the Fire Prevention Plan guidance, to which site operators must comply if they are to be granted an environmental permit by the Agency.
Agency difference
The Agency’s latest guidance on fire prevention, published in July 2016, indicates that site operators should seek to enforce a maximum height for waste piles of 4 metres and a separation distance of at least 6 metres for waste piles (see letsrecycle.com story ).
In its introduction to the guidance, WISH states: “Fire is an ever-present possibility at most waste management sites, if only because many wastes are readily combustible. Operators should therefore ensure they have adequate controls in place to prevent fires and, should a fire occur, that the risks to human health, property and the environment are minimised.
“This guidance aims to give an overview of fire safety management on solid waste management sites. It is not the intent to provide a comprehensive guide on all aspects of fire safety, to duplicate general fire management guidance which is available elsewhere or to provide in-depth technical advice. It is your responsibility to ensure that your management of fire safety is adequate.”
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Source: letsrecycle.com Plastic
