Bunding Regulations in Australia: What You Need to Know

Bunding is one of those compliance requirements that tends to get less attention than it needs, right up until a regulator, an insurer, or an environmental incident makes it the most urgent thing on the agenda. 

Whether you’re storing chemical concentrates on a farm, fuels at a depot, or hazardous liquids at an industrial facility, Australian regulations are strict. If a spill has the potential to reach soil, stormwater, or waterways, secondary containment measures are mandatory. 

This guide explains what bunding is, which Australian standards and regulations apply, how capacity requirements are calculated, and what a compliant bunding setup actually looks like in practice.

What is Bunding and What Does it Do?

A bund is a secondary containment structure designed to capture liquid in the event of a primary container failure, leak, overflow, or spill. Many chemicals, fuels, and other liquids have the potential to injure personnel or contaminate environments if they escape their primary containment structures, that’s why it is essential to ensure you have bunding measures in place to contain any spills quickly and effectively. 

Bunding comes in a wide range of designs and options to suit diverse storage needs, from fully enclosed bunds and open bunds to bin liners and pallets. 

Bunding is a regulatory requirement in Australia, and failure to maintain compliant bunding is a legal liability and a potential criminal offence under environmental protection legislation in every Australian state and territory.

Which Australian Regulations and Standards Apply?

Bunding requirements vary depending on the specific hazard class of the stored chemicals, however, there are standard rules that apply as standard:

• AS 1940: Governs the storage and handling of flammable and combustible liquids.
• AS 3780: Governs the storage and handling of corrosive substances.
• AS/NZS 3833 & AS/NZS 4452: Apply to mixed dangerous goods, toxic chemicals, and pesticides

Australian Standards, such as AS 1940 – Storage and Handling of Flammable and Combustible Liquids, require that the bund holds at least 110% of the volume of the largest single container or tank stored inside the area, or at least 25% of the total aggregate storage volume of all containers combined, whichever volume is greater.

Moreover, bund walls and floors must be made from materials that resist chemical breakdown from the specific liquids stored. The areas must also be completely sealed off from general stormwater drains, soil, and unapproved sewer lines to prevent potential contamination. 

Under AS 3780, incompatible classes of dangerous goods, such as Class 3 flammable liquids and Class 8 corrosives, are required to be kept in separate bunded areas to prevent mixing, contamination and major accidents.

To learn more about safely storing chemicals in Australia, you can explore our full guide or reach out to our team for detailed and tailored advice.

How Bunding Capacity is Calculated

The 110% rule is the foundational capacity requirement across Australia, this means that the bund must be capable of holding 110% of the volume of the largest single container within the bunded area. This ensures that a complete failure of the largest tank can be fully contained with capacity to spare. Alternatively, the bunding must be able to hold at least 25% of the total aggregate storage volume of all containers combined.

It is important to note that bund capacity refers to the actual volume of liquid the bund can hold, rather than the gross internal dimensions of the bund walls. This is important because any items placed inside the bund will take up space and reduce the capacity of liquid the bund can hold. Therefore, when calculating capacity you are calculating the net available volume, after accounting for displacement from items stored inside the bund.

Bund Construction and Material Requirements

Bunds must also be constructed from materials that are impermeable to the liquid being contained, resistant to degradation, and feature no unsealed gaps where liquids can escape.

Rotomoulded polyethylene bunding is ideal for most applications as it is impermeable to a wide range of agricultural and industrial chemicals. Additionally, rotomoulding ensures there are no seams of weld points that can fail over time. 

While polyethylene is safe for most chemical storage applications, it is essential to confirm suitability prior to selecting a bund as the concentration of the chemical, storage temperature, operating conditions and even what was previously stored in the tank can all influence performance. By providing the chemical name, SDS, concentration and operating temperature, our team can work with material suppliers and chemical compatibility data to help determine whether a polyethylene bund is suitable for your application.

There are two main types of bunding configurations:

• Open bunds: Suitable for indoor applications where overhead clearance allows, providing easier access for refilling and pump connections.
• Closed bunds: Best for outdoor or exposed applications where rainfall or other debris can get into the bund and reduce volume available.

Pallet bunds are also available in both open and closed configurations to suit your site and needs.

Where Bunding is Required

Bunding is a mandatory requirement across any industry or sector that stores hazardous liquid chemicals on-site, such as:

• Agriculture and farming
• Food and beverage sectors
• Transport and logistics depots
• Civil industries
• Mining and resource management

Inspection, Maintenance, and Documentation Requirements

A bund that meets the relevant standards at the time of installation can fall non-compliant if not maintained appropriately. To ensure your bunding remains compliant and ready for an emergency, it is essential to conduct regular inspections of bund walls, floor, and any penetrations for cracking, chemical attack, or physical damage. Moreover, bunds should be inspected and cleaned regularly to ensure that debris or water are not sitting in the bund and reducing the capacity. 

If you ever notice that your bunding is showing signs of cracking, UV degradation, or deformation from chemical exposure, it should be replaced immediately. This ensures that you always have a fully compliant and usable solution available in the event of a spill. 

Additionally, inspection records must be maintained and easily accessible for regulatory audits. In the event of an incident, documented compliance history is critical evidence of due diligence, and can protect you from significant legal liabilities.

Maintain Compliance with Reliable Bunding Solutions

Maintaining compliant bunding is essential for ensuring safety and preventing serious environmental contamination in the event of a spill or leak.

At Global Rotomoulding, our industrial bunding range covers the full spectrum of secondary containment requirements. All products are manufactured from UV-stabilised polyethylene using precision rotomoulding, and are engineered to meet Australian standards for chemical resistance and structural integrity.

Contact our specialists today to discuss your chemical storage needs and find the right bunding solution for your site.

Important Notice

Chemical resistance information is provided as a guide only and should not be considered a guarantee of field performance. The long-term suitability of any tank is influenced by factors including tank design, processing, installation, operating conditions, chemical concentration and temperature. Final suitability should always be confirmed before storage of any chemical product.