Underground blaze triggers explosives alert from SafeWork SA

Quick answer: SafeWork SA has warned mine and quarry operators about the safe use and storage of explosives after fire broke out inside an underground explosives store during a shift handover. Damaged blasting cartridges leaking a black substance were identified as the most likely origin of ignition.

Operators of mines and quarries are being alerted to the safe practices for using and storing explosives after an incident occurred at a mine site in South Australia last year.

SafeWork SA said inspectors were called to investigate a fire that broke out at the underground magazine of the mine site during the changeover of shifts.

Inspectors examined the fire incident, and the Mine Operator enlisted a forensic fire investigator to ascertain the likely cause.

An investigation by SafeWork SA uncovered that several blasting cartridges were found to be damaged and had emitted a black substance from their casings.

“The most probable cause of the fire was found to be due to the auto-heating of the explosive substances leaking from damaged cartridges causing ignition of the explosives or the carton,” SafeWork SA stated.

Why damaged explosive cartridges present a fire risk

Nitroglycerine-based and emulsion products can begin to self-heat once packaging is compromised, and leaking material may ignite without any external flame. Black or oily residue on a casing should be treated as a warning that the cartridge has degraded.

Because heat builds slowly, workers may not notice a developing problem until smoke or flame appears — often during quieter periods such as a crew change in an underground mine.

Safe storage of underground explosives

Under the Work Health and Safety Regulations, explosives are classed as hazardous goods that demand secure, purpose-built storage with tightly controlled access. Operators should:

• Inspect every carton and cartridge for damage, leakage or discolouration before use
• Quarantine and dispose of degraded product through an authorised explosives supplier
• Keep enclosures cool, dry, well ventilated and clear of combustible packaging — see our Cleaning Without Adequate Ventilation SafeWork Method Statement for related ventilation controls
• Ensure all electrical fittings within the store suit the hazardous area classification
• Rotate stock so older product does not remain beyond its shelf life

Electrical ignition sources demand strict control

Stray current, static discharge and faulty wiring remain among the most common ignition pathways underground. An electrical inspection programme, carried out by a licensed electrical worker, should cover lighting circuits, cabling and switchgear serving the store and surrounding drives.

Electrical isolation procedures also need documenting before maintenance occurs anywhere near stored product, and every electrical fault should be logged, repaired and verified.

Transport and handling of explosives

Movement of explosives between surface storage and the face is governed by the Australian Explosives Code, which sets out transport rules for packaging, placarding, segregation and driver competency. Purpose-built transport units keep cartridges upright, restrained and shielded from crushing damage.

• Use only approved transport containers, and never carry detonators alongside cartridges
• Plan each transport route to reduce travel through occupied workings
• Confirm that every transport driver holds current licensing and authorisation

Plant, equipment and mobile machinery

Mobile plant working close to an explosives store introduces heat, vibration and impact energy. Diesel plant should be shut down and parked well clear of stored product, while loading plant needs maintaining to prevent hydraulic leaks or exhaust sparks reaching packaging.

Pre-start checks on drill rigs and charging units give supervisors early visibility of defects, and a documented plant maintenance register demonstrates due diligence to regulators. Where contract plant enters the storage area, verify machine condition and operator authorisation beforehand.

What construction and quarry operators should take from this

Blasting is not confined to extractive operations; construction projects, tunnelling and civil earthworks all rely on explosives, so identical failure modes apply. Construction principal contractors carry duties to verify subcontractor competency, storage arrangements and emergency response capability.

Across construction and quarrying alike, a documented risk assessment for explosives handling deserves review after every explosives incident, near miss or product change.

Smaller construction businesses often rely on template systems to keep documentation current, while larger construction groups fold these controls into a broader management framework.

Risk controls and safety documentation

Effective control combines engineering measures, competency and active supervision. Recommended actions include:

• Completing a task-based risk assessment covering storage, handling and firing
• Briefing plant operators, shot firers and supervisors on damaged-product reporting
• Testing emergency and evacuation arrangements with local fire services
• Recording health monitoring where crews handle nitroglycerine-based product
• Reviewing safety data sheets and manufacturer storage limits annually

Further reading and safety resources

Regulator notices offer practical learning for anyone accountable for safety systems. Related coverage includes a bus roll-away that triggered a safety warning from SafeWork SA, a carbon monoxide alert issued by the regulator, and a fake inspector warning.

Learn more here.