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 Underground Storage Tank? Click Here
  • Why should I test the soil before my tank is decommissioned? Click here
  • Is There A Problem If I Have An Abandoned Tank On My Property? Click Here
  • I haven't used my tank in 20 years, could it be leaking? Click here
  • What do I do if there is water in my tank? Click here
  • What do I do if my tank has leaked? Click Here
  • Do I have to take soil samples? Click here

Underground Storage Tank Uncovered

Hole in UST (unusually large)

Contaminated soil to be removed

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".

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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. .

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What should I do with my abandoned tank? (Oregon)

  • The tank should be decommissioned following a DEQ approved method.
  • DEQ requires a soil sample if tank is to be a certified decommissioning..

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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..

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Why should I test the soil before my tank is decommissioned?

  • A tank may leak prior to decommissioning.
  • Without a soil test, it is difficult to tell if the soil around the tank is contaminated.
  • The tank may be tested after decommissioning.
  • If contamination is detected after the tank is decommissioned, the cost of clean up greatly increases.
  • As of March 15, 2000, DEQ requires soil sample testing prior to certified decommissioning. (Oregon)
  • If a soil sample test is not performed the decommissioning cannot be registered with DEQ..

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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..

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I haven't used my tank in 20 years, could it be leaking?

  • All steel tanks will eventually rust and have the potential to leak.
  • According to DEQ 50%-80% of tanks are leaking. .

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What do I do if there is water in my tank?

  • Do not put more oil into the tank until a soil sample test is performed.
  • Water in your tank may mean there is a leak.
  • Water in the tank may also be the result of condensation.
  • If the soil sample shows there is no contamination present, have the water pumped out of your tank before ordering more oil..

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What do I do if my tank has leaked?

  • Cancel the automatic fill program with your oil company.
  • Have the tank pumped out as soon as possible to minimize contamination and cost.
  • Call Advanced EnviroTech, Inc. to discuss clean-up procedures based on the level of contamination and site specific requirements.

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Whose responsibility is it to report contamination to DEQ?

  • If the homeowner discovers the contamination, it must be reported to DEQ within 72 hours.
  • If Advanced EnviroTech, Inc. discovers the contamination, we are required by law to report the contamination within 72 hours of discovery..

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If My Underground Storage Tank Has Leaked, What Should I Do? (Washington)
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.
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Do I have to take soil samples?

  • Many lenders and buyers frequently require soil testing before property transactions.
  • Sellers should consider s/s testing to limit their liability.
  • Soil testing is required by DEQ when a tank is decommissioned and certified with the state.

My tank is under concrete. Can soil samples still be taken?

  • The first step is to have your tank professionally located.
  • Even though the fill pipe is visible, the tank could be running in any direction beneath the concrete.
  • Advanced EnviroTech, Inc. will then use a roto-hammer to make two four inch holes in the concrete to allow soil samples to be taken.
  • We will patch the concrete once the samples are obtained.

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What do I do with my unused heating oil from the tank?
When performing a tank decommission, Advanced EnviroTech, Inc. will pump out your oil tank as a courtesy.

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Mailing address:

10350 N. Vancouver Way, #313,
Portland, OR 97217

Phone numbers

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