Continued expert reaction to Hurricane Harvey including reports of an explosion at a chemical plant in Houston as a result of the flooding.
On the reports of explosions:
Prof Andrea Sella, Professor of Inorganic Chemistry at UCL, said:
“Organic peroxides are crucial reagents for a wide variety of industrial chemistry. For example they are used as radical initiators for a variety of bulk polymers and resins. The compounds, however, are pretty notorious for their instability and over many decades they have been responsible for many accidents.
“It is worth considering that a peroxide compound in essence contains both the fuel and the oxidizer in the same molecule and is therefore only one small step away from ignition. Once decomposition begins the temperature rises and this can result in a runaway fire or in some cases an explosion. As a result of this the HSE, for example, has specific directions for their handling and storage both in small laboratory situations and in industrial settings. It is crucial to keep them cool and typically separate from other, especially flammable, materials. In the case of industrial sites, the quantities of these materials can be very significant indeed, significantly heightening the risks both to the installation and to the surrounding neighbourhood.
“A complicating factor here, as has been observed many times over the past few years, is urban sprawl gradually engulfing chemical plants. Because accidents are unusual planners can come to underestimate the severity of what are likely to be quite rare events. It is worth noting in this context that the Trump Administration intends to make a 30% cut in the EPA’s budget and has already slashed funding to the Chemical Safety Board, two of the key regulatory agencies whose responsibility it is to minimize and understand chemical risks.”
Dr Rory Hadden, Rushbrook Senior Lecturer in Fire Investigation at the University of Edinburgh, said:
“Organic peroxides of the type stored at the facility are commonly used in the manufacture of many everyday products. These materials are stable when stored correctly however if they are allowed to heat, the molecular structure begins to break down. This breakdown of the molecular structure releases energy. This will increase the temperature and lead to a further increase in the rate of decomposition. This is referred to as a self-accelerating decomposition and the process may continue over many hours or days until the temperature becomes sufficiently high that the material will ignite and burn.”
Tony Ennis, Director of Haztech Consultants Ltd, a Risk Assessment consultancy for hazardous industries, said:
“Arkema manufacture a range of organic peroxides at the Houston plant. The end products are widely used in the plastics industry e.g. as catalysts used in the curing of plastics and resins.
“The raw materials used by Arkema are various organic materials and hydrogen peroxide. Some of these materials are highly reactive and will burn rapidly. A number of the materials used & produced on site are kept refrigerated for safety as they are temperature sensitive.
“If power is knocked out to the plant then the refrigeration will fail and the chemicals will become unstable. As many of these materials are stored in 200 litre drums, the drums may well explode, especially if damaged or dislodged by flood water causing loss of containment.
“Some of the fumes produced by the burning may contain small amounts of toxic materials and in the present flood situation, the safest alternative is to allow the fire to burn itself out [whilst watching from a safe distance].”
Dr Clifford Jones, Emeritus Professor of Engineering at Aberdeen University, and currently Adjunct Professor at Federation University, Australia, said:
“The Arkema plant in Texas makes ammonia. There are two sides to the hazard. One is that ammonia is very toxic. The other is that it is explosive. Case studies can be invoked for each.
“That black smoke was observed means that something containing carbon had caught fire. It is recorded in the news releases that nearby are substances capable of burning. Additionally to the thermal hazards there will be smoke toxicity issues with these.”
On the hurricane:
Dr Ivan Haigh, Associate Professor in Coastal Oceanography at the University of Southampton, said:
“There are two unique things about this event. The first is the combination of multiple hazards. The event has generated a large storm surge, with unprecedented rainfall, and there have been very strong winds as well. The second unique thing is the slow-moving nature of the storm, which has meant that high storm surges and very heavy rainfall have remained for several days over one area.”
Dr Dann Mitchell from the School of Geographical Sciences at the University of Bristol, said:
“There is some evidence that Hurricane Harvey was enhanced by human induced planetary warming (climate change). For instance, we know that a warmer planet holds more moisture, and so rain can be more intense. We know that warmer oceans give more energy to hurricanes such as Harvey, causing them to be more severe. The current high pressure over most of North America also acts as a ‘block’, keeping Harvey in place, another potential signature of climate change. Ultimately, however, no one has performed a specific climate attribution study on this event, so we cannot say with high confidence if and to what extent climate change has altered Hurricane Harvey.”
Prof Barry Bogin, Professor of Biological Anthropology at Loughborough University, has written this blog about the impact of the flooding on children, which you can quote from if you want: