5 main causes of underground storage tank leaks
Leaks from underground storage tanks present a real threat to the environment. They can cause damage to land and water courses, they can be harmful to human health, and they can cost a fortune to clean up.
According to UK government guidance, the damage caused by leaks is likely to be greater if the underground storage tank is close to a local watercourse or a groundwater location. Other risky areas are water abstraction points and environmentally sensitive areas.
Here are five main reasons that leaks can occur.
1.Corrosion of steel
Tank Decommissioning experts are often called in because steel tanks have corroded. Older tanks that were installed prior to 1980 are mainly made of steel. Some will have considerable corrosion by now. Modern tanks have cathodic protection systems that prevent the oxidation process that causes rust.
When Tank Decommissioning experts are called in, they often find older dispensers have been fitted above soil. Drips land directly on the ground, and over time, the quantity of polluting material builds up. These days, dispensers have spill containment underneath them to catch spills.
In the early underground storage tanks, the fill port was simply a pipe sticking out of the ground! During filling, it was quite common for liquid to contaminate the ground when hoses were disconnected. In modern tanks, there is a spill bucket that intercepts spillages and drains the liquid back into the tank.
4. Corroded lines and fittings
There are steel pipes called lines that transport liquids to the dispenser from the tank, and these can corrode if they are made of steel. To overcome this issue, modern lines are made of double-walled fiberglass. They are also monitored for leaks electronically. Modern leak detectors work by measuring the fluid pressure within the lines, and they can shut down the flow if a leak is detected.
5. Submersible transfer pumps
These are the pumps that are used to pump the liquid out of the tank toward the dispenser and are located at the top of the tank. A manhole or sump is built at this point for repairs and servicing.
High-pressure leaks at these pumps or at the pump fittings can result in significant leaks in older tanks. Modern pumps have spill protection devices to overcome this.