The Environment Agency (EA) has defended proposed measures in its Fire Prevention Plan (FPP) guidance on stack sizes and maximum burn times, despite strong industry opposition.
During consultation earlier this year, there were 116 responses to the question: ’Do you agree with our approach for a maximum acceptable duration for sheltering [people kept indoors with windows shut] to be three to four hours?’ Of these, only 27 replied yes, while 73 said no and 16 did not know.
One respondent suggested that evidence from the Waste Industry Safety and Health forum (WISH)’s waste fire burn tests should be incorporated into updated regulations before they are issued.
To this, the EA said it did not want to delay its own guidance until analysis from the WISH tests had been completed in October. “We will consider the results of the WISH fire tests when available and propose further changes to our guidance if appropriate,” it added.
Public Health England supports the EA’s preferred burn limit, saying: “In practice and considering the prolonged durations of some past waste fires, three to four hours is an ambitious target, particularly for existing waste sites, but it would significantly reduce typical burn durations.
“It also represents a time period during which continued sheltering is likely to be both feasible and remain effective for the majority of the potentially affected population in typical fire scenarios.”
Respondents also raised the disparity between the EA’s four-hour burn limit and WISH’s current 24-hour recommended cap on waste fires.
The EA said: “We understand that the WISH guidance seeks to bring fire under control within 24 hours, whereas we would commonly categorise a fire of this nature and scale as a serious or significant incident based on the impact on the local community and the environment.
“Indeed, one of our key corporate scorecard measures is to reduce the number of serious and significant incidents and, in order to achieve this target, we need to minimise both the scale and duration of waste fires.”
Maximum acceptable pile heights for unprocessed wood have been reduced from 10m to 5m and the maximum pile volume to 750cu m in the latest FPP version. For processed wood, the limits are stricter at 3m maximum pile height and 150cu m maximum volume.
Some 117 respondents answered the EA’s question: ’Do you agree with the maximum prescribed pile sizes?’ Only 22 replied yes, while 75 said no and 20 did not know.
In general, the agency said, waste operators objected to the pile sizes while emergency response organisations were generally supportive. It said a number of respondents did not believe that there was a link between pile size and risk of self-combustion.
“We recognise the need to clarify the objectives for the pile sizes, and also to evidence the data and methods used to derive them. The pile sizes have been devised both to reduce risk of self-combustion of waste and to enable active fire-fighting to extinguish a fire within four hours.
“Where we have been made aware of the outcomes of fire investigations, many have cited self-combustion as the likely cause.”
It also quoted Fourier’s law of heat conduction, a study by Wang et al (2006), and self-combustion predictive models by Semenov, Thomas and Frank Kamenetskii as evidence.
Other consultation questions such as ’Do you believe that, wherever possible, firefighting water should also be prevented from entering surface or groundwater?’ received more positive responses.
Andy Hill, chair of the Wood Recyclers Association, said he was pleased to see the results, although he would have preferred them at the same time as the latest version of the FPP.
“We need time to review the document in full but, initially, I can see that the four-hour burn time has remained despite an overwhelming majority of respondents commenting against it.
”I will be interested to read the reasons why those views were ignored, and hopefully to get some scientific evidence to back up the EA’s decision to see this remain in the document.”