HCDG information for licence and permit holders

HCDG pose significant community security and safety risks if they are not used or stored appropriately. The potential for the illicit misuse of ammonium nitrate may result in serious consequences such as mass casualties and destruction. Therefore, access to HCDG is limited to only those with a lawful need.

HCDG are also known as security sensitive ammonium nitrate (SSAN) in some jurisdictions such as Queensland, Western Australia and South Australia.

Ammonium nitrate solutions and products that are Class 1 explosives are not referred to as HCDG. Solutions refer to water based mixtures where all the HCDG is dissolved and there are no visible solids or particles in the HCDG water mix for example UN 0222 – Explosive Class 1.1D; UN 2426 – liquid, Class 5.1.

The United Nations (UN) numbers for HCDG are listed below:

Note: Dangerous goods are assigned to UN numbers and proper shipping names according to their hazard classification and their composition.

Persons who import or export HCDG must be licensed and must notify WorkSafe Victoria at least 7 days before the proposed import/export date. 

A notification must include:

• the type and quantity of HCDG being imported
• a certificate of analysis for each batch of the HCDG
• identification details of the ship, boat or aircraft transporting the HCDG
• the arrival location of the ship, boat or aircraft
• the authorisation and contact details of the recipient of the HCDG
• where the HCDG will be stored on arrival in Victoria
• the authorisation and contact details of the person or agent who will transport the HCDG from the arrival location to its storage destination

The HCDG licence conditions are for specific activities. Should these activities change or cease, the license holder must notify WorkSafe as soon as they become aware to review the licence and change or cancel the licence conditions.

Licence holders can notify WorkSafe by completing the Application for a licence to access high consequence dangerous goods form.

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Ammonium nitrate (formula NH4NO3; CAS Number: 6484-52-2) is a salt with a white appearance when pure. Ammonium nitrate is classified as a Dangerous Goods Class 5.1 oxidising agent.

Ammonium nitrate melts at 170°C and decomposes above 210°C. It is a strong oxidiser and can react violently with incompatible materials such as, acids and metals, or when heated.

Ammonium nitrate, when pure, is stable and poses few risks, however the risks significantly increase when ammonium nitrate is contaminated or exposed to fire and heat.

Ammonium nitrate is predominately used in the manufacture of fertilisers and is commonly supplied in the form of prills or granules. In the mining industry, it is used as an explosive for rock blasting.

The main risks associated with ammonium nitrate include, but are not limited to:

• fire
• decomposition
• explosion

If ammonium nitrate is mixed or becomes contaminated with combustible or incompatible materials the risk of fire or explosion is increased.

Incompatible materials include but are not limited to:

• flammable or combustible liquids
• organic matter
• powdered metals
• explosives
• other products such as oil-based pesticides and weedkillers

Ammonium nitrate can also become dangerous when heated in a confined space or exposed to a strong shock from a fire or an explosion.

Ammonium nitrate does not burn, however as an oxidising agent it will supply oxygen to fuel a fire and support combustion.

There is a higher likelihood of explosion if ammonium nitrate has become molten and pooled. For example, the risk of an explosion can increase if molten ammonium nitrate drains into a confined space such as a drain or sewer.

Note: extinguishing ammonium nitrate fires.

Ammonium nitrate fires need to be fought by the application of large volumes of water. They cannot be extinguished by smothering with foam or dry chemical extinguishers. Steam should not be used to extinguish an ammonium nitrate fire as steam may cause the ammonium nitrate to decompose, this can increase the risk of explosion.

Providing ventilation, in an ammonium nitrate fire, can assist reduce pressure build-up and temperature increases. If ammonium nitrate decomposes in a fire it will produce copious amounts of toxic brown and yellow fumes (toxic gases, nitrogen oxide and ammonia gas).

Ammonium nitrate incidents and explosions often occur due to contamination, or the mixing of ammonium nitrate with combustible materials such as fuel or oil.

Incidents involving ammonium nitrate must be notified to WorkSafe Victoria when there is:

• theft, or attempted theft, unexplained loss of the HCDG

  Note: Under the Dangerous Goods Act 1985 all fire, explosion, spills, leakages and escapes involving dangerous goods must be reported to the nearest fire authority or police station.

• when there is a release, fire or uncontrolled situation
• an escape, spillage or leakage of any dangerous goods
• an explosion, fire, harmful reaction or the evolution of flammable, corrosive or toxic vapours involving dangerous goods
• an unintended event of a risk control measure or human intervention, is likely to result in an emergency

Specific duties apply following an incident including reporting an incident, see WorkSafe Report an incident page for further details.

Report an incident

Employers and self-employed persons also have duties under the Occupational Health and Safety Act 2004 to report incidents.

Criteria for notifiable incidents

Ammonium nitrate stores need to be free of combustible materials and contamination including organic matter, hay, straw, animal feed, wooden pallets.

The main principals for HCDG stores include, but are not limited to:

• securing stores against unauthorised access
• maintaining minimum distance between stacks and walls of 1.2m and do not store ammonium nitrate in stacks higher than 3m
• regularly clean walls, framing or structures
• keeping ammonium nitrate dry
• regularly inspecting the ammonium nitrate for caking

  Note: The risk of explosion increases if the product gets wet and the surface forms a crust on the outside. The crust confines the decomposing gases making explosions more likely.

• where ammonium nitrate is stored in a building, the building should be:
  • well-ventilated
  • single-storey
  • made of a material that will not burn
• avoiding confinements - store away from drains, channels and pits where molten ammonium nitrate from a fire could become confined
• controlling potential ignition sources
• storing away from populated areas

Note: Capacities and separation distance of stacks of ammonium nitrate packages and intermediate bulk containers (IBCs) are detailed in AS 4326:2008.

The DG (Storage & Handling) Regulations require occupiers to eliminate any risk of interaction with other substances or articles that are incompatible or reactive with ammonium nitrate. If it is not reasonably practicable to eliminate the risk, occupiers must reduce the risk so far as is reasonably practicable.

The following dangerous goods cannot be kept in an ammonium nitrate store:

• flammable and combustible liquids
• flammable gases
• sulfur, hexamine and finely divided metals
• substances sensitive to explosive decomposition
• readily combustible solids, for example, hay

Some materials and dangerous goods may be kept in an ammonium nitrate store but there are strict limits and conditions regarding the amount of ammonium nitrate and segregation distances of at least 5 m. Any proposed mix storage is discouraged due to incompatibilities. A list of incompatible materials can be found in section 9.3.4.3 of the Australian Standard 4326:2008 The storage and handling of oxidizing agents.

AS 4326-2008 provides specific information on storage or HCDGs.

Occupiers must ensure risk control measures are regularly reviewed and, if necessary, revised when:

• there are changes for systems of work
• you become aware of new information about the hazardous
• if an incident occurs
• if risk control does not adequately control the risk

Storage facility inspections should be conducted to ensure:

• there are no areas where confinement could occur
• there are no combustible and incompatible materials in the store

  Note: small amounts of contaminants can act as a catalyst and cause a fire.

• all walls and floors are clean and free from debris
• all contaminated equipment is washed free of ammonium nitrate
• there is no build-up of ammonium nitrate dust on the ledges of storage bays or storage facility frame
• the storage facility frame has not corroded or decomposed potentially contaminating the stored ammonium nitrate
• emergency information and notices with the words 'DANGER – NO SMOKING, NO NAKED LIGHTS – REPORT FIRE IMMEDIATELY' are prominently displayed.

The condition of ammonium nitrate needs to be monitored for stability or signs of caking as part of a quality control system. This could include periodic sampling and analysis of the stored ammonium nitrate.

Other issues associated with the storage of ammonium nitrate include the absorption of water from the atmosphere (hygroscopicity) causing the breakdown of the prill granules and caking.

Ammonium nitrate should not be disposed in large quantities as it should be consumed in the process for which it was produced such as explosives or fertiliser.

Occasionally unwanted or unused ammonium nitrate, for example cessation of business activities, may require disposal. In these situations, the manufacturer should be consulted and a licenced and qualified waste contractor should be engaged to undertake the disposal activities.

Ammonium nitrate is highly water soluble and can be dissolved in water for disposal, it can harm livestock if it contaminates water courses. Nitrate residues should not be buried as organic material present in soil could result in a reaction and explosion.

The licensee must complete a site/facility inspection to ensure the ammonium nitrate has been disposed of safely and the facility has been decommissioned.

Other environmental duties may apply, see Environment Protection Authority for more information.

Containers used for the storage of Ammonium Nitrate should be triple rinsed with water before disposal. Other material such as packaging materials, pallets, bags, ropes and slings contaminated with ammonium nitrate must also be washed before disposal. These articles can then be disposed of in accordance with local environmental and government guidelines.

The dangerous goods labelling and placards must be removed and the containers need to be checked for any residue and dry before disposal.

Employees need to be trained in the correct washing procedures.

Waste providers must have the appropriate licences to handle, store, transport and dispose of HCDG Ammonium Nitrate.