06:41 pm, Friday 26 April, 2013
A number of people died and the small town of West in Texas was devastated by the massive explosion that reportedly levelled a fertiliser plant last week.
The casualties included emergency responders and volunteer fire crew members however the authorities cannot confirm the number of casualties till they have thoroughly searched the rubble that was once peoples homes.
Because it wasn’t just the factory that was flattened by the explosion, many homes in the town of 2800 were affected as well and the area remains toxic and volatile because of the presence of ammonium nitrate making the searching difficult.
Our hearts go out to the people that are affected by such an enormous workplace accident and we cannot help thinking why did it happen and what steps could have been taken to avoid it.
The cause of the explosion
The first sign of a problem was when a fire broke out at the fertiliser plant. Firefighters decided to start evacuating the immediate area once they realised the potential hazards of the chemicals stored at the site and the explosion occurred approximately 20 minutes after the fire started.
Complex investigations still need to be completed. It is reported that authorities knew that anhydrous ammonia was stored at the site yet the companies risk management plan, filed with the EPA 12 months ago, stated that the company did not handle flammable materials.
As a result sprinklers, water-deluge systems, blast walls, firewalls or other safety mechanisms were not installed at the site.
However, it is a requirement of the state that every facility that handles anhydrous ammonia must have safety measures in place as it is considered a flammable substance.
There is also conjecture that ammonium nitrate was also at the site and used by a partner company. Also known as a common fertilizer, it is considered more volatile than anhydrous ammonia and has featured in a number of bombings and explosive accidents over the years.
Ammonium nitrate possibly caused the explosion that rocked the town.
The dangers of the chemicals involved
In Australia this chemical classified is a Dangerous Good and a Hazardous Substance and is a liquid that forms a gas after it is released from pressure.
Anhydrous ammonia is used for preparing of fertilizers and is commonly an ingredient. It is used in the manufacture of explosives and rocket fuel, is used for chemical synthesis, condensation catalyst and is a latex preservative.
The known hazards:
- Ammonia is a flammable gas that may explode with the application of heat and is volatile when stored under pressure
- It reacts violently with acid and in particularly dangerous when spilled or the gas is released accidently
- Nitrogen is produced when it combusts in either air or at an extreme temperature
- Ammonia causes severe burns, eye damage, respiratory irritation and is toxic on inhalation
- Ammonia is very poisonous for aquatic life and because it is water-soluble it has the potential to pollute drinking water
In Australia this ammonium nitrate is classified as a Dangerous Good because of its physiochemical hazard = it is an oxidising agent. It is used for the production of explosives and fertilisers.
The known hazards:
- It is a dangerous oxidising agent
- It releases toxic gas when it comes in contact with acid
- When heated it can decompose and produce toxic gases such as oxides of nitrogen and ammonia
- It will make any fire that is present worse because it creates oxygen as fuel
- It is harmful to swallow and an irritant to the eyes
- In large quantities it can poison plants, animals and cause algal bloom in static bodies of water.
How this accident could have been avoided
The explosion that rocked West was massive with a 30-meter-fireball and the force registering as a 2.1 magnitude quake damage was widespread and potentially avoidable.
Some of the factors that could have contributed to the magnitude of the event are:
- The fertiliser plant was physically located in the middle of a residential area where schools, houses and a nursing home were located close by. By locating a facility such as this in an industrial zone the impact on the town and its residents would have been significantly reduced.
- Confusion about the chemicals that were present by the first responders who may have acted differently in the first instance if they had known that ammonium nitrate was also stored at the site.
- The absence of essential safety measures that would control or even prevent such an explosion from happening.
- A lack of monitoring of this facility by the state and federal authorities to ensure that it was complying with the required regulations and disaster management planning requirements.
How these chemicals are monitored
As ammonium nitrate is an explosive it is classified as “Security Sensitive Ammonium Nitrate” (SSAN) in Australia, a classification that is applied to all chemicals in Australia that have more than 45% ammonium nitrate in them.
Everyone that is involved with the transport, storage, handling or application of a SSAN must be licensed which involves a police check and a politically motivated violence check (PVM).
They are restricted products and only available for purchase to those that have a legitimate need.
In Australia we also have strong regulations around Major Hazard Facilities where large quantities of hazardous materials are stored, handled or processed.
They are obliged to:
- Identify all major incidents and hazards
- Conduct risk assessments to identify safety risks
- Implement control measures for identified hazards including the minimising the risk of a major incident
- Prepare an emergency plan
- Create a Safety Management System for the operation of the facility
- Be able to show the effectiveness of their safety systems in case of a major incident
In Texas, even though historically they are aware of the explosive nature of ammonium nitrate from a previous incident, the authorities were concerned with the health and environmental impacts of the fertiliser plant in West rather than the explosive potential of the 2400 tonnes of ammonium nitrate stored there.
The responsibility was passed to different state government organisations and none felt they had the authority to check for potential explosive incidents at the site even though anhydrous ammonia is listed with OSHA (the US Occupational Health and Safety Administration) as a ‘highly hazardous chemical which presents a potential for a catastrophic event at or above the threshold quantity.’