Leakage Of Underground Petrol Storage Tanks

This article appears in the Surface Coatings Australia Journal, Vol. 30 No 3. March 1993.

Underground tanks have long been used to store liquids but they have not all been properly protected against the effects of corrosion, says David Blackburn the Australasian President of the Australasian Corrosion Association (ACA).

There have been several notable leakages of underground storage tanks in recent years. For every reported leaking tank there must be many more that have leaked or are leaking now that have gone unnoticed or have not been reported as having leaked.

Recently in New Zealand there was an underground tank which leaked 15,000 litres of petrol from a service station. Some of this petrol found its way into sewers and Telecom ducts causing severe problems.

The United States Environmental Protection Agency said that thousands of the estimated three to five million underground tanks in the USA containing dangerous goods are leaking. They also estimate that there will be many more leaking tanks in the years ahead. They cited one case of a woman who ran off a cup of water from the tap, let it settle then set fire to the surface liquid which was obviously a contaminant which had entered the water supply system.

In Australia, there have been many problems caused by leaking tanks and pipes. These leakages have caused severe problems, both in terms of loss of product and contamination both to the product in the tank and to the surrounding soil and water sources. The cost of finding and repairing the leak can be very high, as is the cost of cleaning up the contaminated soil and other contaminated items.

David Blackburn says that the majority of tanks have never leaked because they are properly protected against corrosion, properly maintained and have never had any mechanical damage. These corrosion protective measures are put into place before and during installation. An unprotected steel tank or pipe placed in the ground will corrode because of reaction between the steel and soil, or because of the presence of stray direct currents in the ground.

David Blackburn recommends that for expert advice on corrosion protection on the installation of underground tanks or pipes or on the repair of same, contact the Corrosion Prevention Centre, Box 634 Brentford Square, Vic 3131. Phone 1800 333 303 or (03) 9874 0800, who maintain a Consultants Register and will refer you to experts with appropriate expertise.