Silo Safety and Confined Spaces

A person conducting a business or undertaking (PCBU) must manage the risks associated with confined space, such as a silo, at a workplace including confined space entry permits, signage, communication, emergency procedures and written risk assessments.

Designers, importers, suppliers and manufacturers have a standard duty to eliminate or minimise entry into a confined space, so far as is reasonably practicable, in relation to the plant or structure.

General safety

• The atmosphere in silos can be dangerous
• Silos should be located clear of houses, overhead power lines, animals, children and water holes
• The dust in a silo may be explosive particularly if the humidity is low – do not smoke or have any other ignition sources
• High temperatures in silos can result in heat stress for anyone entering them. If possible, do the job from outside
• Wear appropriate respiratory equipment particularly when fumigating

Safe entry

• Do not enter a silo unless you have to
• If a silo must be entered, work in confined space procedures must be put in place including having somebody standing by in case of difficulties
• The responsible person should ensure that adequate checks have been done prior to issuing to a worker a confined space permit to enter
• A warning notice of possible dangers should be placed adjacent to the entry point and maintained in good condition
• Never enter a silo before turning off and isolating the auger and make sure no one can start an auger while someone is inside
• Stay on the ladder above the level of compacted or bridged grain while dislodging it
• Make sure ladders start above child height
• All entry points should be locked and keys held in a safe place under the supervision of a responsible person

Check the machinery

• Guard auger drive train (belts, pulleys, drive shafts) and the rotating screw flighting
• Locate mobile augers on firm, preferably flat ground, and operate at shallow (less than 45°) angles to prevent them overbalancing
• Lower mobile augers when transporting
• Never start augers hidden from your view before checking the area is clear of people
• Make sure all machinery is serviced and maintained regularly

Avoiding structural failures and falls

• Take care when a new product is stored in a silo. Every stored material has different characteristics and a silo designed to store one product may not be suitable for another.
• Follow manufacturer's instructions exactly for preparation of the concrete pad.
• Use the 'bedding-in' procedure when filling by drawing off a rubbish bin full of grain.
• Keep people well clear when filling or emptying the silo especially children.
• An engineer should be consulted before modifying a silo because a simple change can drastically alter its structural stability. Equipment attached to a silo can impose dangerous loads.
• Provide a simple roof platform and ladder cages where necessary.
• Provide a wire mesh guard which is hinged permanently on all external openings above the maximum level of grain.
• Use a fall arrest system where ladders are without safety cages and to anchor to the roof platform.

Confined spaces

Working in a confined space has the potential to increase the risk of injury from noise, being overcome by fumes, gases or oxygen depletion, high or low temperatures, manual handling and slips, trips and falls.

Storage tanks, silos, field bins, wet and dry wells, vehicle service pits, manure and silage pits are just some of the examples of confined spaces anyone working on a farm or a rural workplace could expect to work in.

Some of the environmental hazards linked to working in confined spaces include:

• oxygen deficiency caused by absorption of grains
• carbon monoxide build up in wells from the exhaust of an operating internal combustion engine if located too near its opening
• the presence of contaminants in the atmosphere caused by disturbing decomposed organic material in a bin letting out toxic substances
• the build-up and release of gases like ammonia, methane, carbon dioxide and hydrogen sulphide in manure pits
• suffocation caused by solids such as grain, sand or fertiliser.

If you are working in a confined space, you must follow certain procedures including:

• placing a stand-by-person outside the confined space to talk to anyone in the confined space and implement emergency procedures if required
• providing personal protective, rescue, first-aid and fire suppression equipment and training for workers entering the confined space
• supplying safety harnesses and safety or rescue lines where there is a danger of falling during the ascent or descent to access the confined space
• erecting signs that show entry is only permitted after signing the entry permit
• ensuring the area is well ventilated.

Other safety procedures

• If trapped by grain, don't panic or the grain will pack tighter. Shield your face and chest with arms and clothing to create space for breathing.
• Empty the bin as quickly as possible by opening any side outlet then cut flaps in the cone or walls all around the base using power tools.
• Access to tools, breathing equipment, communications and first aid in an emergency is part of the emergency planning and training procedures.