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For any business that burns through diesel — earthmoving, transport, mining, quarrying, civil construction or agriculture — keeping fuel on site is no longer a convenience, it's an operational necessity. Self bunded fuel tanks</strong> have become the standard for bulk fuel storage across Australia because they combine large-volume capacity with built-in spill protection, helping operators stay compliant, reduce downtime and cut their fuel costs.

At A-FLO Equipment, we design, manufacture and install self bunded diesel tanks through our Australian-built Fueltainer range — from compact 9,200-litre combo units to high-capacity tanks holding up to 94,710 litres of diesel, with diesel-only models to 110,000 litres. Below we explain how self bunded fuel tanks work, why they matter, and how leading operators like the Australian Defence Force, Toll and Bull Bros Earthmoving rely on them every day.

What Is a Self Bunded Fuel Tank?

A self bunded fuel tank is a double-walled storage tank with an inner tank that holds the fuel and an outer tank that acts as an integrated bund. If the inner tank ever leaks, the outer wall captures the fuel — typically with capacity for at least 110% of the inner tank's volume — so there is no spill to the ground and no contamination of soil or waterways.

Unlike a single-skin tank, which requires a separate concrete bund wall to be constructed around it, a self bunded tank arrives with that secondary containment already engineered in. That makes it:

• Compliant with the secondary containment requirements set out in Australian Standard AS 1940 (The storage and handling of flammable and combustible liquids).
• Relocatable — the tank can be lifted and moved to a new site as your operation changes, without demolishing infrastructure.
• Fast to deploy — no civil works for a bund wall, so the tank can be in service quickly.

This is why self bunded tanks are sometimes called double-walled, twin-walled or integrally bunded fuel tanks. They all describe the same core principle: a tank within a tank.

Why Choose a Self Bunded Fuel Tank?

Environmental protection and compliance

The integrated bund is your safeguard against an environmental incident. A single uncontained diesel spill can trigger EPA penalties, clean-up costs and reputational damage. Self bunded tanks remove that risk by containing leaks at the source.

Reduced fuel costs through bulk buying

Storing fuel in bulk lets you purchase diesel at wholesale rates and ride out price fluctuations, rather than paying retail at the pump. For high-consumption fleets, the saving per litre adds up quickly across a year.

Less downtime, more productivity

On-site refuelling means machines and trucks fuel up where they work, instead of travelling to a service station. That recovered time — and the fuel saved on the trip — flows straight to the bottom line. This was exactly the driver behind the Bull Bros Earthmoving project below.

Safety built in

A-FLO's self bunded tanks can be specified with auto shut-off nozzles, overfill protection, high-level alarms, emergency stop controls and bulk fuel filtration, creating a safe, controlled refuelling environment for operators.

Self Bunded Diesel and AdBlue Combo Tanks

Most modern diesel fleets also need AdBlue (diesel exhaust fluid) for their SCR-equipped engines. Rather than running two separate systems, A-FLO's diesel and AdBlue combo tanks store both fluids in a single self bunded unit, with fully segregated compartments and independent, DEF-compatible dispensing for each — preventing cross-contamination while keeping both fluids on hand at the point of use. With AdBlue supply under pressure, on-site DEF storage is now a genuine resilience measure for any fleet, mine site or depot.

The A-FLO Fueltainer Range

Fueltainer self bunded tanks are containerised, double-walled units built on ISO-style footprints for straightforward transport, placement and service access. The diesel/AdBlue combo range spans the following capacities:

Fueltainer Diesel/AdBlue combo tank range — diesel and AdBlue stored in fully segregated compartments.

Model	Diesel (SFL)	AdBlue (SFL)
FT9/2.5	9,200 L	2,550 L
FT23/4.5	23,415 L	4,500 L
FT35/5	35,000 L	5,000 L
FT56/7	56,680 L	7,000 L
FT70/7	69,690 L	7,000 L
FT85/10	83,320 L	10,000 L
FT86/10 (Integrated Pump Bay)	Combo	10,000 L
FT95/10	94,710 L	10,000 L

Need diesel only? A-FLO also supplies Fueltainer diesel-only tanks (11,000 L–110,000 L), the Fuelbox range (5,000 L–20,000 L) for permanent on-site storage, and the Fuelcube range (1,000 L–6,000 L) for compact yard installs and mobile refuelling.

Configure your Fueltainer

Units are available as bare tanks or fully configured dispensing stations, with a lockable integrated pump bay housing all equipment. Options include:

• Diesel pumps — 240V standard, or high-flow 1.5HP submersible for high-throughput plant and multi-vehicle refuelling.
• AdBlue pump packages — dedicated DEF-compatible transfer pumps, hoses and nozzles, fully segregated from diesel hardware.
• Filtration — 10-micron particulate and water separation on the diesel outlet to protect injectors and fuel systems.
• Metering — digital or mechanical flow meters with resettable totals and transaction logging.
• Monitoring — automatic tank gauges, high-level alarms and remote monitoring.
• Fuel management — BSmart, Fluidlink AFM or Fluidtrack FMS for user/vehicle ID, access control and audit-ready reporting.

Self Bunded Fuel Tanks in Action: A-FLO Case Studies

The best measure of a fuel storage solution is how it performs in the field. Here are three operations relying on A-FLO self bunded tanks.

Smarter Fuel Storage with Fuel Management

A self bunded tank stores your fuel; a fuel management system tells you who used it, where it went, and how much is left. A-FLO's Fluidtrack is an Australian-made, web-based fuel management system with no ongoing subscription costs, while Leveltrack online tank gauging gives you live visibility of stock levels so you never run dry mid-shift. Together they turn a fuel tank into a fully accountable, data-driven asset — exactly what Toll and Bull Bros use to control consumption.

Industries We Supply

• Earthmoving and civil construction
• Transport, logistics and freight
• Mining and quarrying
• Agriculture and primary production
• Defence and government
• Local councils and infrastructure

Choosing the Right Self Bunded Fuel Tank

When specifying a tank, consider your daily fuel burn and required days of autonomy, whether you need diesel only or a diesel/AdBlue combo, your required dispensing flow rate, the level of fuel management and reporting you need, and any site access or relocation requirements. A-FLO's projects team handles the full process — design, manufacture, delivery, installation and commissioning — so you receive a single turnkey solution rather than a box of parts.

Frequently Asked Questions