Frequently Asked Questions Regarding Underground Storage Tanks:

• What is an "Abandoned" Underground Storage Tank? Click Here
  
  
• What Should Be Done With An Abandoned Underground Storage Tank? Click Here
  
  
• Why Should I Decommission My Abandoned Underground Storage Tank? Click Here
  
  
• Is There A Problem If I Have An Abandoned Tank On My Property? Click Here
  
  
• If My Abandoned Underground Storage Tank Has Leaked, What Should I Do? Click Here
  
  
• What Is Polyurethane Foam? Click Here
  
  
• What Is The Difference Between A Foam Filled or Slurry Filled Tank? Click Here

What is an "Abandoned" Underground Storage Tank?

Many underground storage tanks are no longer being used, rendered obsolete by piped-in natural gas or electric baseboard heat. An underground storage tank that is no longer in use is considered "abandoned".

What Should Be Done With An Abandoned Underground Storage Tank?

Department of Ecology and many Local Fire Departments recommend permanent closure for abandoned underground storage tanks. The process of permanently closing a tank is referred to as "decommissioning"". A tank may either be decommissioned by capping, filling it with an inert material such as slurry or foam or by removing it from the ground. Decommissioning also involves removing heating oil and sludge from the tank.

Many underground storage tanks have been abandoned with oil still in them. You should consider arranging to have any remaining oil removed from the abandoned tank if you do not immediately decommission it. This will help prevent possible contamination of soil and ground water.

Why Should I Decommission My Abandoned Underground Storage Tank?

Abandoned underground storage tanks are a potential source of contamination of the soil and ground water and may pose a fire and explosion hazard under certain conditions. Underground storage tanks can corrode and deteriorate and possibly cave-in and collapse. They should be decommissioned whenever they are no longer used or whenever there are questions about their structural integrity or about their ability to hold product without leaking.

Under the Model Toxics Control Act, a tank owner may be held liable for contamination caused by a leak.

Many times the tank does not become an issue until the home owner decides to sell their home and at that time has an inspection done on their home. These inspections are often done one to two weeks before closing. Before finalizing the sale of a house, lending institutions and home buyers may want sellers to remove or decommission the abandoned heating oil tank.

Is There A Problem If I Have An Abandoned Tank On My Property?

Discovering an abandoned tank on your property doesn't mean that it has leaked or caused an environmental problem. Even a leaking abandoned tank does not necessary pose a health risk because most leaks are usually small and localized. Although most abandoned underground storage tanks do not cause major environmental problems or health risks, ignoring an abandoned tank is not recommended. Even if it has not yet caused a problem, it could in the future.

Dealing with your tank now may prevent or at least minimize future problems and expense. Some abandoned tanks have leaked heating oil, resulting in contaminated soil and ground water and expensive cleanups. Leaking oil can migrate into a basement or crawl space of your home and, although unlikely, the fumes from the oil could cause a fire or health risk. Also, an abandoned tank may cause a safety hazard even if it has never leaked. Over time tanks will corrode and deteriorate and possibility cave-in and collapse.

If My Underground Storage Tank Has Leaked, What Should I Do?

If a tank has leaked, the Washington State Department of Ecology regional office does have reporting requirements based on the extent of contamination found. Minor leaks or spills from residential heating oil tanks do not have to be reported to the Washington State Department of Ecology. Minor leaks are those that affect only the soil near the tank.

According to Washington State Department of Ecology's report R-TC-92-117, it is the owner's responsibility to evaluate the extent of contamination caused by the leak, then determine if it is a threat to human health and the environment and clean up any contamination caused by the leak.

A significant leak requires that the tank be removed and as much of the contaminated soil be removed according to the regulations indicated by the state Model Toxics Control Act.

What Is Polyurethane Foam?

Polyurethane foam is a safe close cell material. Water cannot penetrate polyurethane. When you consider the health and safety factors, along with the strength and structural integrity of the product, polyurethane foam is by far the logical choice for abandoned underground storage tanks. Polyurethane foam provides structural integrity and has tensile strength and compressive strength and eliminating the chance of caving. It sets up like concrete. An underground storage tank filled with polyurethane foam will not float or pop out of the ground. Various polyurethane foams are used in construction, typically for roofing, ground perimeter insulations, wall insulation and sheathing.

The polyurethane foam used to fill underground storage tanks presents no health hazards. It is chemically inert and insoluble in water and most organic solvents. Because of their inertness, polyurethane is the polymers of choice in biomedical applications.

Do not confuse polyurethane foam with urea formaldehyde foam. There is a major problem with urea formaldehyde foam - it's a potential health hazard. In recent years, public concern about the adverse health effects of urea formaldehyde foam insulation has been in the spotlight.

If the underground storage tank needs to be removed from the ground at a later date, the foam in a 300 gallon tank will weigh approximately 80 pounds versus approximately 5400 pounds for concrete slurry.

What Is The Difference Between A Foam Filled or Slurry Filled Tank?

The removal of a polyurethane foam filled tank, if ever required, is less complicated than slurry since the polyurethane foam is relatively light in weight. The foam in a 300 gallon tank will weigh approximately 80 pounds versus approximately 5400 pounds for concrete slurry.