• If applicable

Posted Sunday, March 8th, 2020

Most large building complexes today are designed with a backup generator system, which ensures continuous power in the event of a mains power outage. This generator will be diesel powered and therefore needs an approved diesel tank beside it to provide the specified run times.

However, the installation of a diesel or petrol tank within a building raises immediate concerns as to the safety of people nearby and the environment should a leak or disaster occur. Therefore, it is very important that the correct method of installation is used and the right tank for the application is considered.

In Australia and New Zealand, the common standard used in order to comply is the Australian Standard AS1940-2017, ‘The storage and handling of flammable and combustible liquids’.

The three most common styles or types of installation set out in AS1940-2017 are shown in Clause and is for any tank having a capacity greater than 1000 litres.

  1. A double-wall tank buried in accordance with Clause 5.12; or
  2. Installed on or below the lowest floor level of a building, in a tank chamber in accordance with Clause 5.13; or
  3. A tank having integral secondary containment with an ‘Fire Resistance Level’ (FRL) of 240/240/240 and complying with Clause 5.9.

Environmental protection and compliance continues to escalate as a concern and the community is much more aware of the potential risks of pollution, fire and flooding and we have very strict regulations covering fuel storage and the consequences and penalties for any neglect can be huge. Installing an ‘above ground tank with integral secondary containment that is 4-hour fire-rated’ compliant tank offers huge benefits for the environment, now and in the future. Why? It is much easier to install, it is seismically safer, it can be serviced easily and removed easily in the future if need be. Also, if you have a high water table problem, you’ll have no concern as to the tank ‘popping’ out of the ground when the fluid level is low.

Here are some notes to assist with the understanding of the three options discussed in AS1940-2017.

Underground oil tank removed

Underground Fuel Storage Tanks (UST)


An Underground Fuel Storage Tank (UST) comes with many implications including the purchase and installation process being more expensive upfront, the tank can also quietly corrode overtime, is difficult to inspect and repair, leaks aren’t easily visible, and are more expensive to remove when “worn out” (especially if they leaked into the soil, and your area requires clean-up of contamination).

The costs associated with installing a UST are significantly higher than those for setting up an Above Ground Fuel Storage Tank (AST). UST require expensive excavation work which includes a variety of permits, land use consents and specialized equipment for the installation.

Other factors to consider if burying a tank within a building include access pits for servicing, proximity to property boundaries and building foundations and corrosion protection.


We had a look at the costs of installing a 5000 litre double wall fiberglass UST versus a 4-hour fired-rated double walled SuperVault. Both options exclude pipework.

To install an Underground Fuel Storage Tank   
5,000L Tank
 $15,000  including excavation, placement and back fill @ $4.00 p/l = $2,000  $35,290
To install an Above Ground Fuel Storage Tank
5,000L Tank
 $26,085 including placement and bolt down = $1,500  $27,585



When maintenance is necessary, it is less expensive (and faster) to make repairs on an Above Ground Fuel Storage Tank (AST) rather than a Underground Fuel Storage Tank (UST). Repairs are a key concern for long-term costs. For installation, above ground fuel tanks tend to be less expensive overall.

In almost all areas of the globe, the responsibility lies with the owner to ensure that their UST’s does not leak, and it is certainly recommended that if you choose this option that you establish a well-documented system of care for your tank. UST’s record keeping should include maintaining a record of detection system performance; recording results of sampling, testing or monitoring; and documenting calibration, maintenance and repair of the equipment.


There are many factors that affect the cost of removing an Underground Fuel Storage Tank. The most important factors include the tank’s size, whether there is evidence of leaking and what was stored in the tank. UST’s do cost much more than AST’s to remove, due to the added labour of excavation and the need to locate any underground pipes or utility lines. The larger the tank, the more it costs to remove. In summary, if you choose this option, you’re deciding the tank will be there forever regardless of consequences.

Removing an Underground Fuel Storage Tank requires specialist attention and is mostly left in place and decommissioned by filling with concrete or some other like substance. Replacing an UST with a larger sized option is usually not an option, unless another location within the building is available.

Underground oil tank removed
Fire chamber image in building

A Fire Rated Chamber


This method is not as difficult as the underground option, but in effect comes with most of the difficulties and is potentially more expensive to install than going underground. In the construction phase, you will need to consider that the walls and roof need to have an FRL (Fire Resistance Level) of 240/240/240. You will need to design a removable roof tank placement, a fire-rated door that is designed to stay closed, separation distances from other tanks, and foundations of the building and boundaries of other properties will need to be considered and separated from.

It will also be important to ensure that the concrete products used to construct the room have certification to FRL. Although commonly referred to as fire rating, the correct term to describe the fire resistance of a building element is FRL (Fire Resistance Level). The FRL is the ability of a building element to withstand a fire under test conditions for a certain period of time and consists of the three criteria being, structural adequacy, structural integrity and insulation. This means that if a building element were exposed to a standard fire test, it would not be expected to fail for 240 minutes, (4 hours) in each of the three criteria.

  1. Structural Adequacy: this means that for a period of 240 minutes (four hours) the product being tested was able to support a load while subject to fire conditions.
  2. Integrity: this means the product did not disintegrate or crack so as to see the flames of the fire or for gases to escape.
  3. Insulation: which means the product being tested did not transfer an average temperature reading that exceeds 180°C above the ambient temperature.


Servicing a tank in a fire-rated tank chamber is only possible if the chamber is designed with a compliant fire rated door and is sufficiently larger than the tank enabling the technician to have access to all four sides of the tank.


Removing the tank in the future will be difficult and in the event of a larger tank being required, the chamber will need to be altered at considerable cost to allow for the installation.

A Fire Rated Tank with a Fire Resistant Level of 240/240/240

Fuelchief take the hassle out of your whole decision by engineering a compliant customised Above Ground Fuel Tank (AST) called the SuperVault. This engineered fuel tank is 4-hour fire rated and is recommended due to its fire protective safety for commercial sectors.  The SuperVault tank offers elite fire-rated, bullet-proof, impact-resistant technology and has been designed, fabricated and tested in accordance with SwRI 95-03 which makes it the safest and most durable tank in the world. In many circumstances where diesel or petrol needs to be stored in commercial buildings, the SuperVault is the only permitted tank. The SuperVault has been engineered to withstand conditions – from the sub-zero temperature of the Arctic to the blistering heat of the desert. No other fuel storage system in the world can provide a higher level of certified fire protection, insulation, and fuel security than a Fuelchief SuperVault.


The SuperVault rectangular series is the only tank in the world with the correct certification for installation within buildings. Clause 5.9.4(c) of Standards Australia state that Tanks having an FRL of 240/240/240 shall be regarded as complying with the requirements for tanks in chambers (see clauses 5.13.1 & 2).


Regular maintenance is important with all fuel tanks to ensure a stable fuel supply in all conditions and applications. The most important service function is to ensure fuel is clean and free of contaminants. To do this, tanks will need a maintenance schedule that includes the ability to remove all fuel, flush the tank and refill. All fuels are subject to condensation and will need to be checked for water and sludge build up to ensure nothing gets transferred to expensive equipment or prohibit generator start up in the event of a power outage.

The interstitial insulation provides maximum thermal protection to the internal steel tank, thus minimising condensation build-up. This insulation material reduces heat transfer from the outer tank to the inner tank, therefore minimising the risk of an environmental disaster or the event of a pool fire. The porous nature of the insulating material allows for monitoring of leakage from the primary tank. In hot climates, the insulation also minimises fuel losses due to evaporation.  The SuperVault emergency vent controls the pressure in the tank in extreme fire conditions to eliminate explosion.


You can easily relocate your SuperVault from building* to building by simply unplugging from associated pipework, unbolting from your seismic restraints and lifting out. Above Ground Storage Tanks (AST’s) are much easier to move than their below-ground counterparts. If you need to move your tanks for new construction, you can easily move them elsewhere. In turn, this ease of movement makes any upgrade possible more appealing if your power requirements change. Need a bigger generator, remove the tank and put in a bigger one, no hassle at all.

*this is based on the design of the room, emergency supply room should be designed with consideration given to maintenance and/or tank removal in the future.

In Summary

In our opinion, it is a sensible decision and one with a lot less implication to make the ‘SuperVault’ choice. We are now in an age where the community is much more aware of the potential risks of pollution, fire and flooding and we have very strict regulations covering fuel storage and the consequences and penalties for any neglect can be huge.

Best engineering practice and design of fuel storage tanks has continued to develop to a point where above ground storage tanks offer 100 percent integrity. This has been achieved mainly by the introduction of the SuperVault tank, with advanced leak detection and online contents monitoring.

The Fuelchief team and our suppliers and manufacturers work very closely together to provide the very best solution for your application. Whether it is a small or large installation, we have the knowledge and experience to provide the solution that works for you today and in future generations. All of our tanks will remain an asset for you the business owner, and that can be relocated easily, if for any reason the operational requirements should change.



Blog article by Praneel Lal