How to safely install and maintain an underground fuel tank

For businesses that have limited space for fuel storage facilities, using an underground fuel tank is the most viable means to address their petrol storage requirements. Since they are installed under the earth, this type of fuel tank provides a convenient and space-saving way of storing large amounts of fuel. Underground tanks are commonly used by fuel suppliers, trucking fleets and other industrial businesses that need to keep large amounts of petrol as these tanks can hold up to 200,000 litres of fuel.

However, using an underground fuel tank has its risks. Rust and corrosion of this type of tank is a common problem, which can result in leakage of the contents that may go unnoticed for some time. Leakage from underground fuel tanks, even in small amounts, can cause extensive contamination and damage to the soil and ground water. Clean up or treatment of this contamination can be very expensive.

The risks of rust, corrosion and leakage can be reduced by following proper environmental management and maintenance practices. In this article, we discuss how you can safely install and maintain underground fuel tanks so that its risks and impact on the environment is minimised.

Follow mandatory standards

Installation of underground fuel tanks must adhere to the guidelines as stated in the Australian Standards AS 1940-1993: Storage and Handling of Flammable and Combustible Liquids. The Australian Institute of Petroleum has also released a code of practice as stated in CP4-2002: Design, Installation and Operation of Underground Petroleum Storage Systems. These standards must be strictly followed to ensure the proper and safe installation and operation of underground fuel tanks.

Comply with the basic installation principles

Determine the soil type and ground water level of an area before installing the underground tank. Underground fuel tanks should not be installed in clay soils as clay has components that accelerate corrosion. To protect a tank against corrosion, it should be installed in an inert material such as sand. Also, do not install an underground fuel tank in an area with a high ground water level. The deeper the ground water level, the lower the risk of water contamination. Underground fuel tanks should also not be installed within the water table or the saturated areas of soil.

Select a double wall tank

Underground fuel tanks come in double wall models that offer more protection against rust, corrosion and leakage. A double wall underground fuel tank is made of a steel primary inner tank enclosed within a fibre glass reinforced plastic outer tank, thus minimising external and internal corrosion. The double walls also provide protection against leakage. The steel primary inner tank is assembled, welded and tested for tightness so it is almost impossible for the fuel to spill through. But if there is leakage, the outer tank will hold the fuel in and prevent it from coming in contact with the soil and ground water.

Regularly monitor the tanks

It is crucial to conduct regular monitoring of the tanks to detect leaks so that any leakage or breach can be investigated and addressed immediately. There are different ways of monitoring for leaks including stock inventory monitoring, automated tank gauging or ATG systems and interstitial monitoring. Among these monitoring methods, interstitial monitoring - wherein sensors are installed between the two double walls - is the most advanced and is highly recommended.

Some final words

If an underground fuel tank has not been used for a period of six months, it should be properly decommissioned following mandatory standards and code of practice. Proper decommissioning is important to avoid health risks and contamination of soil or ground water. If you need help in managing and maintaining your underground fuel tank or if you are looking for an alternative fuel storage facility, talk to a trusted fuel tank supplier as they can help you determine the most appropriate storage system for your business.