1.1. LOCATION OF MAGAZINE
1.1.1. Public Risk
When siting a magazine the risk management process can be carried out to identify hazards that may arise from its proximity to public installations, facilities and roads. Risk acceptability should be evaluated based on the quantity of explosives stored in the magazine (magnitude of the hazard) and the possible consequences of an unplanned explosive incident.
1.1.2. Proximity to other Magazines
The separation distance of magazines in proximity to each other should be determined based on the quantity of explosives stored and the magazines used. Further guidance can be attained from AS2187.1 – Table 3.3.3.2 in relation to distances from protected works and separation distances from other explosive magazines and ammonium nitrate storage.
1.1.3. Proximity to Ignition Sources
When siting the magazine the risk management process can be carried out to identify hazards that may arise from its proximity to likely ignition sources. Such sources arise from proximity to refuelling depots, vegetation, rubbish or mineral matter. Magazines are required to have the immediate and adjacent area cleared of any substance likely to cause sparks or catch fire, and to establish an acceptable firebreak around the magazine. Note: Guidance on the width of the firebreak can be attained from local fire fighting authority, or Queensland Fire and Rescue Service.
1.1.4. Vehicle Access Routes
When siting the magazine a risk management process can be carried out to identify hazards that may arise from proximity to vehicular access routes and roadways used on site. The number of access routes to the magazine and the types of vehicles and the frequency of their proximity to the magazine should be considered (AS 2187.1). Best practice is ensuring that all vehicles perform at least one 90 degree turn to access a magazine location thus reducing the risk of an out of control vehicle having direct route into the storage area.
1.1.5. Activities within site
When siting the magazine a risk assessment can be carried out to identify hazards that may arise from proximity to other activities on site. Mining activities that involve employees and equipment should be at a safe distance in the event of an explosive incident occurring (AS 2187.1).
1.1.6 Weather Protection
When siting the magazine, it should be located as to provide all-weather access. This includes adequate drainage to prevent deterioration of the access roadway and prevent water entering into the magazine (AS 2187.1). In conditions where adequate drainage cannot be provided catchment tanks such as that shown below in Figure 1 can be utilised to protect the magazine from water ingress.
Figure 1: Water catchment on the side of a magazine
1.1.7. Use of Natural Ground Features
When siting the magazine, the use of natural ground features should be considered to enhance physical protection of employees and the public. Alternatively, mounds can be built around the magazine to provide additional protection (AS 2187.1).
Figure 2: Relocatable magazine protected by earth mounds
1.1.8. Security
When siting the magazine, do not make it easy for unauthorised personnel to locate or access the magazine. If possible it should be located on site in a position that is not viewable from outside the mine or quarry. Adequate security installations should be in place to prevent accidental or unauthorised disclosure of the magazine location (AS 2187.1).
1.1.9. Licences
A person is required to hold an authority to store explosives for a quantity of explosive of 10 kg or more. Quantities of less than 10 kg are exempt from a license to store, however a person licensed to use explosives is the only person allowed to possess such explosives.
1.2. FABRICATION REQUIREMENTS
1.2.1. Portable Magazines
All portable magazines have to be constructed in accordance with specifications given in AS 2187.1, or with a system of at least equivalent safety and security approved by the Chief Inspector of Explosives.
1.2.2. Relocatable Magazines
Relocatable magazines have to be constructed in accordance with specifications given in AS 2187.1, or with a system of at least equivalent safety and security approved by the Chief Inspector of Explosives. Explosives in excess of 10kg may only be stored in a relocatable magazine by a person who holds an authority to store and who stores the explosives in accordance with the licence, conditions imposed, and applicable regulations (s44 Explosives Act 1999).
1.2.3. Fixed or Permanent Magazines
Fixed or permanent (non-relocatable) magazines located above ground are to be constructed in accordance with specifications given in AS 2187.1, or with a system of at least equivalent safety and security approved by the Chief Inspector of Explosives. Explosives in excess of 10kg may only be stored in permanent magazines by a person who holds an authority to store and who stores the explosives in accordance with the licence, conditions imposed, and applicable regulations (s44 Explosives Act 1999).
1.2.4. Bulk Explosive Storage
Storage tanks used for bulk explosives such as ANFO and bulk emulsions are to be constructed in accordance with specifications given in AS 2187.1 and the Australian Explosives Manufacturers Safety Committee (AEMSC) Code of Practice for the Precursors for Explosives, or with a system of at least equivalent safety and security approved by the Chief Inspector of Explosives.
All bulk explosive storage facilities require that a person holds an authority to store and stores the explosives in accordance with the licence, conditions imposed, and applicable regulations (s44 Explosives Act 1999). Security and safety considerations given to bulk explosive storage facilities need to be equivalent to that of explosive magazines.
1.2.5. Magazine Exteriors
Persons and machinery approaching any magazine should be able to clearly distinguish the magazine. Magazines should be painted in a light colour to maximise light reflectance and be protected against corrosion to prevent structural damage and deterioration (AS 2187.1).
1.2.6. Magazine Interiors
Certain explosives are susceptible to initiation from friction and sparks caused by metal installations. Where exposed metal is present in the interior of the magazine an inner lining should be utilised. The inner lining should be free of iron or steel and be of close jointed construction (AS 2187.1).
1.3. SECURITY
1.3.1. Remote Security
To enhance the security of a surface magazine consideration can be given to incorporating either a camera or alarm system with the required door and locking devices specified in this Guidance Note. All alarm and camera fittings and installations inside the explosive storage area are required to comply with AS 3000 for
electrical equipment in hazardous locations (refer to Section 1.6.2.2).
1.3.2. Locking devices
Locking devices for all magazine types are required to be in accordance with AS 2187.1, or with a system of at least equivalent security. As specified in AS 2187 the door or lid of every magazine needs to be fitted with a six level ‘safe lock’. Where a padlock is used it shall have a hardened shackle and pad constructed to provide a high level of resistance to fracture and rupture. It shall also have a key system known as a ‘restricted system’ if the padlock is of the pin-tumbler type. Where the padlock is of the lever type, there shall be a minimum of five levers.
1.3.3. Holding Down Bolts
Where there exists the possibility of the magazine being removed by unauthorised persons a provision should be made for holding-down bolts or another equivalent method to protect external portable and relocatable magazines (AS 2187.1).
Figure 3: Relocatable magazine fixed in cement to prevent unauthorised removal
1.3.4. Perimeter Fences
A perimeter fence should be installed around the magazine for additional security purposes. In determining whether fencing is required, consideration should be given to the magazine’s location and security requirements. It should be noted that a perimeter fence is not intended to provide complete security of explosives, but act as a deterrent to unauthorised access. Guidance on the fabrication of the fencing can be found in AS 2187.1.
Figure 4: Magazine with chain and barbed wire fencing
1.3.5. Door Hinges
It is important that the integrity of the door hinges and hinge lugs match the integrity of the lock provided. In the past illegal access to explosives has been gained through using a hacksaw blade on the hinges of the magazine. To prevent such access to the hinges the construction of the hinge lugs on the door should be in accordance with requirements in Australian Standard 2188. The integrity of the weld used to join the hinge lug to the door is also to be of a satisfactory standard to prevent the lug from detaching from the magazine, in the event of a forced entry. The strength of these welds should be monitored at each inspection or audit. Any non-compliance found during an audit or an inspection should be fixed as soon as practicable.
1.4. MARKINGS
Every magazine is to be marked on the door or lid with either the word ‘EXPLOSIVE’ or ‘DETONATOR,’ as appropriate. The markings are required in red lettered characters on a white background and sized to make them clearly defined. In addition an explosive hazard class diamond is required on the magazine door. A clearly defined ‘NO SMOKING or NAKED FLAMES’ sign should be positioned at the entrance of the magazine to warn persons entering the magazine area.
A sign is also required at the entrance of the magazine to warn persons at the magazine of their liability to penalty for an offence if reasonable precautions and reasonable care is not taken to prevent an explosives incident at the magazine (s48 Explosives Act 1999).
Figure 5: Explosive hazard class diamond
1.5. SEGREGATION
Storage sites for the explosive magazine and detonator magazine shall be located as to reduce to acceptable levels the risk of sympathetic detonation between the different storages. The separation and segregation distances specified in AS 2187.1 are based on international testing and need to be observed as a minimum, however this minimum distance can be increased to further reduce the risk.
1.6. UTILITY REQUIREMENTS
1.6.1. Water Installations
If water is required within the vicinity of the magazine, the location of the installation needs to be so as to prevent water coming into contact with the explosives. It should be positioned as to not cause erosion or degradation to the access or foundations of the magazine. If necessary, a sump should be used to prevent water from accumulating in areas.
1.6.2. Electrical Installations
1.6.2.1. Lighting
Lighting in magazines may be either natural or artificial. Electrical fittings inside the magazine should be avoided, however if no alternative option is available, wiring should be suitable for electrical equipment in hazardous areas (AS 3000). Explosion protection for electrical equipment should be provided according to the classification of the hazardous area. A list of explosion-protection techniques and their applicable standards can be found in ESC-1 ‘Electrical Installations and Equipment in Hazardous Areas at Explosives Manufacturing Facilities and Storage Areas.’ Alternatively, lighting can be located outside the magazine and arranged to shine into the magazine.
1.6.2.2. Electrical Equipment
Electrical equipment and installations should be avoided if possible, due to the inherent risks associated with their presence. Electrical arcing of equipment can produce an ignition source that is capable of initiating certain explosives. If electrical wiring or installations are necessary inside the magazine it needs to be in accordance with electrical equipment for hazardous areas (AS 3000). Professional advice should be sought before installing electrical equipment in magazine areas.
1.7. ENVIRONMENTAL CONDITIONS
1.7.1. Ventilation
Ventilation should be adequate to ensure that with the magazine doors closed there is no accumulation of dangerous vapours or excessive heat build up (AS 2187.1). If inhaled certain explosives such as primers can be toxic to persons. There is additionally an explosive risk when explosives are exposed to high temperatures. Air vents should be suitably designed to provide sufficient fresh air circulation and protection from the weather as well as prevent access of persons and foreign objects.
1.7.2. Shade Roof
The magazine should be designed and kept within the prescribed temperature storage range outlined by the explosives manufacturer. Explosives and initiators are at risk of burning or exploding at elevated temperatures as initiation sensitivity increases with temperature. Physical properties (firmness, plasticity, etc) may also change, and storage life/sleep time can be reduced for some explosives. Where the external environment conditions are likely to cause excessive internal temperature fluctuations, a shade roof or similar device should be provided (AS 2187.1).
Figure 6: Shade roof on a steel relocatable magazine
1.8. EMERGENCY INSTALLATIONS
1.8.1. Lightning Protection
1.8.1.1. Vertical Conductors
The need to protect structures and buildings containing explosives within the vicinity or inside the magazine from lightning, can be determined in accordance with AS 1768 – Section 2. Magazines or structures with explosive contents need to be protected from lightning.
Figure 7: Vertical conductor used to protect relocatable steel magazines
1.8.1.2. Earth Terminations
Where earthing terminations are required for lightning protection or the control of undesirable extraneous electricity they need to be in accordance with AS 2187.1. The number of earthing termination for magazines is as follows:
(a) For a portable magazine – one.
(b) For a modular steel or concrete relocatable magazine – at least two at diagonally opposite corners
(c) For a tank magazine – at least two at diagonally opposite corners.
Figure 8: Earthing terminations on a steel relocatable magazine
1.8.2. Fire Fighting Equipment
As required, fire hydrants and on site fire installations should be positioned at the magazine access or immediately inside the magazine. It should be noted that in the case of an actual explosive burning no attempt is to be made to fight the fire. Fire fighting equipment is located in the magazine to prevent the possible spreading of a fire to an explosive. Selection of suitable fire extinguishers and hydrants is dependent on the hazards present within the magazine area. The suitability of an extinguisher for uses on fires that involve paper, wood, liquids or electrical equipment can be determined in accordance with AS 1850 e.g. dry powder, water. Fire hydrants should be clearly marked and have a service tag. Best practice is to advise the local fire brigade and other emergency services of the magazine’s location.
Figure 9: Fire fighting equipment clearly accessible inside the magazine perimeter