Chemical Bunding Requirements in Australia: A Practical Guide for Businesses

If your site stores acids, alkalis, chlorine or other liquid chemicals, sooner or later someone will ask: “Is this bunded properly?” It might be an auditor, an insurer, a WHS inspector or your own maintenance team. This guide explains, in plain English, what Australian work health and safety (WHS) laws, Australian Standards and environmental guidelines say about chemical bunding. It also covers how bund capacity is usually worked out and the mistakes we see most often on small and medium industrial sites.

This article is general information, not legal advice. Requirements depend on the chemicals, quantities, location and state or territory. Check the sources linked below and talk to your regulator or a qualified consultant for your site.

What is a chemical bund?

A bund is secondary containment: a barrier, tray or walled area that holds liquid if the primary container (a drum, IBC or tank) leaks, is punctured or overfills. Bunds range from small spill trays and drum or IBC spill pallets to concrete-walled tank compounds. Their job is to keep spilled chemical, and any contaminated firefighting water, on site and out of drains, soil and waterways, and to stop incompatible chemicals meeting.

What the WHS laws require

Every state and territory except Victoria has WHS regulations based on Safe Work Australia’s model WHS Regulations. Regulation 357, “Containing and managing spills”, is the key provision. In Queensland, for example, regulation 357 of the Work Health and Safety Regulation 2011 says a business must ensure, so far as is reasonably practicable, that where there is a risk from a spill or leak of a hazardous chemical in solid or liquid form, a spill containment system is provided. The system must cover each part of the workplace where the chemical is used, handled, generated or stored, and must keep any spill or leak, and any resulting effluent, within the workplace. The same regulation requires that:

• the spill containment system must not create a hazard by bringing together incompatible chemicals, and
• the system must provide for clean-up and disposal of the spilled chemical and any effluent.

Victoria has its own Occupational Health and Safety framework and dangerous goods regulations, so Victorian sites should check WorkSafe Victoria guidance.

The regulation does not set a single bund size for every situation. Instead, Safe Work Australia’s Code of Practice: Managing risks of hazardous chemicals in the workplace and its guide Managing risks of storing chemicals in the workplace explain how to manage the risk. They also point to relevant Australian Standards for detailed design.

Australian Standards: AS 3780 and AS 1940

• AS 3780:2023, The storage and handling of corrosive substances: covers Class 8 corrosive substances under the ADG Code (for example hydrochloric, sulphuric and nitric acid, caustic soda and sodium hypochlorite). It sets minimum requirements for storage facilities, operating procedures, emergency planning and fire protection, including spill containment. It replaced the 2008 edition.
• AS 1940, The storage and handling of flammable and combustible liquids: applies to flammable and combustible liquids. Safe Work Australia’s Storage of flammable liquids guide summarises the key controls.

Standards are not automatically law, but regulators and codes of practice refer to them, and following them is a common way to show you have managed the risk. Because AS 3780 is a paid document, buy the current edition (or ask your consultant) for exact design figures rather than relying on summaries online.

How big should a bund be?

This is the most common question, and the answer depends on what you store and which guidance applies. Environmental regulators publish practical sizing rules. Two widely used examples:

• EPA Victoria, Liquid storage and handling guidelines (publication 1698): for bulk storage, at least 100% of the largest container, with a suggested extra allowance (10% of the second-largest tank, plus 10% freeboard for rain and firewater). For sites storing small containers such as drums, 25% of the total stored volume plus freeboard where rain or firewater can enter. Its diagrams illustrate an effective capacity of 110% of the largest container, or 25% of the total, whichever is greater.
• Tasmanian EPA, Bunding and Spill Management Guidelines (2015): for drums and small containers, the greater of at least 110% of the largest container or 25% of the total volume stored in the bund.

Worked example (illustration only)

A workshop stores eight 205 L drums of the same, compatible chemical on one bund:

• 110% of the largest container = 1.1 x 205 L = about 226 L
• 25% of the total volume = 0.25 x (8 x 205 L) = 410 L
• Under the “whichever is greater” approach, the bund would need at least 410 L of effective capacity, plus allowance for rain if it is outdoors.

For a single full 1,000 L IBC, the same approach gives 110% = 1,100 L. Check the rated sump capacity of any IBC bund against this figure and against the guidance that applies in your state before relying on it.

Incompatible chemicals: one bund per family

Capacity is only half the story. Safe Work Australia’s storage guide states that incompatible chemicals should never share the same bunding or drainage systems. It also says liquids should not be stored above solids, and it generally recommends at least 3 metres between incompatible goods where distance is used for separation. Common incompatible pairs on water treatment and industrial sites include:

• Acids and sodium hypochlorite (liquid chlorine): mixing releases toxic chlorine gas.
• Acids and alkalis such as caustic soda: a violent, heat-generating reaction.
• Nitric acid and organics or combustibles: nitric acid is a strong oxidiser.
• Oxidisers (hypochlorite, peroxide) and reducing agents or flammables.

Always check section 7 (handling and storage) and section 10 (stability and reactivity) of each Safety Data Sheet.

Choosing bund material and type

• Polyethylene spill pallets and bunds resist many acids, alkalis and salts and are light and portable. Confirm compatibility for strong oxidisers and concentrated acids with the manufacturer’s resistance chart.
• Steel bunds suit many oils and solvents but are attacked by most acids and by hypochlorite.
• Concrete bunds suit permanent tank farms, but need a chemical-resistant lining for acids.
• Double-walled tanks may not need a separate bund, though impact protection should still be considered, as Safe Work Australia’s storage guide notes.

Common bunding mistakes

1. Undersized bunds: putting a full 1,000 L IBC on a sump that holds less than its volume.
2. Mixing families: acid drums and chlorine on the same bund.
3. Rainwater left in outdoor bunds: it eats into capacity. Inspect regularly and remove clean rainwater using a documented procedure.
4. Drain valves left open, or bunds with cracks and damaged walls.
5. Decanting outside the bund: transfers with a drum pump are a frequent spill point, so dispense over containment.
6. No spill kit or clean-up plan, even though regulation 357 requires provision for clean-up and disposal.

A quick bunding checklist

• List every liquid hazardous chemical, its container sizes and total quantity (your hazardous chemicals register).
• Group chemicals into compatible families using the SDS.
• Size each bund for the largest container and total volume, using the guidance that applies to you.
• Allow for rainwater if outdoors.
• Check bund material compatibility.
• Keep SDSs, spill kits and PPE at the storage area, and train staff.
• Inspect bunds regularly and record it.

Spill bunds from Viva Blu

Viva Blu supplies a polyethylene chemical spill bund in single and double IBC sizes. The double model measures 2200 x 1300 x 500 mm with a 900 L sump. We also stock the chemicals that typically sit on them, including sodium hypochlorite 12.5%, hydrochloric acid, sulphuric acid, nitric acid and caustic soda, plus a drum pump for safer decanting. Businesses can register for a B2B account or call 0402 981 808.

Frequently asked questions

Is chemical bunding a legal requirement in Australia?

Under the WHS regulations based on the model laws (regulation 357), a business must provide a spill containment system, so far as reasonably practicable, wherever there is a risk of a hazardous liquid or solid chemical spilling or leaking. The exact form and size depend on the chemicals, quantities and your state or territory.

How big does a chemical bund need to be?

There is no single national figure for every case. Common environmental guidance, such as EPA Victoria publication 1698 and the Tasmanian EPA bunding guidelines, uses the greater of 110% of the largest container or 25% of the total volume stored for drums and small containers, plus freeboard for rain. Check the guidance that applies to your site.

Which Australian Standard covers bunding for corrosive chemicals?

AS 3780:2023, The storage and handling of corrosive substances, covers Class 8 corrosives, including storage facilities and spill containment. Flammable and combustible liquids fall under AS 1940.

Can acids and chlorine share a bund?

No. Safe Work Australia guidance says incompatible chemicals should never share the same bunding or drainage. Acids and sodium hypochlorite can release toxic chlorine gas if they mix.

Do I need to bund an IBC?

If the IBC holds a hazardous liquid and there is a risk of a spill or leak, a spill containment system is required so far as reasonably practicable. IBC bunds and spill pallets are a common way to meet this. Check the bund capacity against a full IBC.