The Environment Agency and the Fire Service have collaborated with the waste industry sector to develop a risk-based approach to manage the size, duration and risk of fires in stored waste facilities.
This has been achieved with the assistance of various umbrella trade organisations representing the waste industry, wood recyclers and tyre recyclers. I am delighted with the progress that we have made to date culminating in the Waste Industries Safety and Health (WISH) Forum publishing a guidance document in October 2014.
However, there remain some gaps in our scientific knowledge and as a result we have embarked on a series of real fire tests to gain a better understanding of fires with a large surface area.
The Chief Fire Officers Association’s (CFOA) opinion is that the “mega stacks” we have seen springing up around the country should be better managed to ensure that the significant disruption caused when they are affected by fire is a thing of the past.
The CFOA advocate that the materials should be divided up into smaller stack/piles and separated by fire resisting construction as a minimum fire engineering approach. However, some operators work to a business model which does not lend itself to this approach and a method for selecting a suitable separation distances, or fire breaks, between unprotected stacks to help prevent fire and limit the size and impact of any fires that do breakout has been developed.
This model is based upon the assumption that fires should burn themselves out within 24 hours. The obvious area that requires further consideration is the effect of radiated heat. After some debate within CFOA and the Health and Safety Executive we agreed on the most appropriate form of the view factor equations.
Using 24 hours unprotected burn time as a base parameter, I propose it will be possible to derive an analytical method of determining the mass of the stack based upon the burning rate of the specific material.
This is the first of the parameters that is being examined with testing taking place at the FPA fire test facility in Blockley. The full-scale tests will take place in spring 2015.
The project aims to take direct measurement of the radiated heat flux produced by various real materials. One of the real challenges faced by the engineer is to quantify the emitter surface area and to achieve this we need an effective method of estimating the flame height and emissivity of the burning stacks.
I hope that by taking direct measurement of the burning material it will be possible to derive a flame height correlation for fire over a large surface area. The tests will also look at a range of other factors such a firefighting tactics, e.g. water efficiency in terms of water volumes. This will enable operators to estimate drainage/storage requirements for their sites.
Fire engineered solutions such as portable compartmentation, an example of which is pictured above, and the effects of conduction through the various temporary partitions will be examined as well.
The environmental impacts fires and firefighting tactics is another major area of research and we will study these effects by sampling smoke and water run-off from the various materials.