Photograph of sketch of parts of a buried oil tank 10 Visual Clues to Find Underground Oil Tanks - how to inspect for evidence of buried oil tanks

  • BURIED OIL TANKS, FINDING - CONTENTS: How to find evidence of buried oil storage tanks (USTs) by visual inspection - Site Inspection Procedures: Visual Inspection of a Building Site for Evidence of Nearly Hidden Buried Oil Tanks; List of Visual Clues of the Presence of a Buried Oil Tank at a Residential Property: outdoor clues & indoor clues; Underground oil storage tank location methods
  • POST a QUESTION or READ FAQs about finding oil tanks buried outside - how to find buried oil tanks or evidence of previous installation of buried oil tanks even if the tank has been removed.

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How to find buried oil tanks:

This article assists property buyers, owners, and inspectors in the location of buried oil tanks or the detection of evidence that an underground (or even an above ground) oil tank is or was in use at a property. We provide an illustrated guide to finding buried oil storage tanks by visual inspection.

The article and photographs used to show the reader ways to find buried oil tanks include examples of clues leading to the discovery of "nearly hidden" buried or underground oil tanks which were found at residential properties and which avoided very costly surprises later for the new owner.

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Site Inspection Procedures: Visual Inspection of a Building Site for Evidence of "Nearly Hidden" Buried Oil Tanks

Buried oil tank schematic (C) CCarson Dunlop AssociatesHere are investigation methods that any home buyer, owner, or home inspector can apply to reduce these risks by looking for evidence that a buried oil tank is or was at a property. Also see Above Ground Oil Tanks: Visual Inspection

[Click to enlarge any image]

Underground oil storage tanks, or UST's, whether still present or previously removed, involve a risk of costly oil leaks and soil contamination which may need to be addressed.

Before hiring an expert oil tank testing or removal company to find the oil tank, test an oil tank for leaks, and perhaps remove or abandon a buried oil tank in place, first we describe and illustrate a series of visual clues that can help you find the most likely location for a buried oil tank at any property.

Take A Walk Around the Property Looking for Buried Tank Clues

Buried Tanks: Look at the property before deciding to hire a tank testing company for professional inspection and testing. You can obtain basic information such as the age (property and tank), tank location, and type of oil tank.

Our sketch at left, courtesy of Carson Dunlop, shows a common buried oil tank installation except that the oil line is shown leaving the bottom of the buried oil tank.

Modern practice usually connects a pair of oil lines to the top of a buried oil tank, avoiding picking up water and sludge from the tank bottom, and avoiding the chance that a leak in piping between oil and building interior will flood the inside of the building with oil.

But the sketch above shows that many buried oil tanks are installed close to the building foundation wall, usually parallel to the wall, since it's easiest to bury the tank in that position during new construction. (The sketch shows the tank at right angles to the wall so that we could portray the various piping arrangements with clarity.) So one of the first places to look for a buried oil tank is close to the building.

Coffee can tank filler cover (C) D FriedmanBut that's not the only possible location for an outdoor buried oil tank at a property. We saw this coffee can in the bushes near a New York home and picked it up thinking we were just cleaning up trash left on the ground. Later in this article you'll see what we found.

Watch out: from a previous use, a buried oil tank may be present or may have been present at a property even if it is now served by an indoor, above ground oil tank or even by LP or natural gas. So don't assume that because you don't see a tank that none was ever used or present at a property. Make a visual site inspection for clues suggesting that one or more tanks is or was present.

Even an alert home buyer or home inspector, not charged with an environmental site survey (nor paid for one) might discover evidence of very costly buried tank problems at a property, simply by attending certain visual details and thinking about what they mean. For the case of buried oil tanks, the next few photographs show two cases of the discovery of a nearly-hidden outside oil tank fill pipe which led to the discovery of buried oil tanks. These tanks had not been properly abandoned, risking significant cost to the property owner or buyer.

Here are Visual Clues of the Presence of a Buried Oil Tank at a Residential Property

The first three photos below show us exploring a hole in a bald patch of grass. Oil spills, such as during a heating oil delivery, can poison the soil so that even when no heating oil is visible or no odors remain, the grass may still refuse to grow in this spot. So we explored further as our photos show.

Many visual or historical clues may indicate that there is or was a buried oil or other fuel tank at a property.

Visible oil tank fill or vent pipes protruding from the ground, depressions near a building, or even areas of dead grass or plantings in a small spot where a buried or previous fuel tank fill pipe may have been installed - from spillage of fuel.

At one site this clue led to the discovery that the tank "removal" had consisted of nothing more than the unscrewing and removal of the fill and vent pipes from the leaky oil tank.

Age and type of property, existing oil fill and vent piping locations, existing oil tank size and ratings, abandoned heating oil lines, marks where equipment was previously mounted, footprints of old heating equipment, and other clues can form strong enough evidence of a risk of a hidden or improperly removed oil tank that we might then advise further investigation.

Coffee Can Hides an Improperly Abandoned Oil Tank Still in Place

The next two photos show us exploring what appeared to be a simple coffee can tossed in the yard of a residential property.

The buried oil tanks discovered below these "nearly hidden" filler pipe openings needed to be tested for leakage and then properly abandoned - a significant expense

What is significant about this "abandoned" UST is that the evidence right at ground level (we could see down into the oil storage tank still in place but not in use) one could infer that the oil storage tank had not been properly abandoned. The risks include un-discovered heating oil leaks into the soil at this property.

See SIGNS OF BURIED OIL TANKS for a detailed discussion of the study of outdoor clues used to find a buried oil tank at a residential property.

Here are Indoor Visual Clues of the Presence of an Indoor or Outdoor Abandoned Oil Tank

In the author's view (DJF), oil tank testing services and professional environmental inspectors are expected to include both a visual screen of the property for clues such as these, and also a combination of other methods to detect buried oil tanks. Some clues that area strong evidence of a buried oil tank at a property are listed and illustrated below.

Abandoned oil lines at a basement wall (C) Daniel Friedman Abandoned dual set of indoor oil pipelines (C) Daniel Friedman
  • Building interior inspection for abandoned oil piping or fuel lines, or patch-marks on foundation walls where such lines may have been removed.
    • Our photo at above left shows a pair of copper oil lines exiting an basement foundation wall. These pipes were almost certainly connected to a buried oil tank. Is the tank still present?
    • Our photo at above right shows an "extra" pair of copper oil lines protruding out of the basement floor even though there was an indoor oil tank piped to the heating equipment. One could follow these older oil lines by markings in the concrete over to the building wall where they penetrated the wall to connect to an older outdoor buried oil tank.
    • Our photo below shows markings in a concrete basement floor that are characteristic of the floor having been cut open to install oil piping. Follow these marks to their destination; if you do not trace these markings to currently active oil piping then further investigation is needed: they probably mark abandoned oil lines an possibly an abandoned outdoor oil tank.
Evidence of oil pipes below a concrete basement floor (C) Daniel Friedman

This photo (above) provides evidence of buried oil lines and possibly an abandoned buried oil tank, as explained in text just above.

  • Historical information about the site is collected.
  • Oil company records may be checked for indications of deliveries or of prior tank service or removal
  • Ground scanning radar may be employed to locate large buried metal objects including underground oil tanks
  • Common sense observation of details, such as the location and placement of oil tank fill and vent piping, if present, can indicate the probable size and type of tanks in some cases.

  • An examination of the history of the property's heating systems - what equipment has been present, removed, changed.
  • Examine the building interior and outside for evidence of heating oil leaks.

Evidence of a buried oil tank, oil leaking through a foundation wall (C) Daniel Friedman

Our photo at above left shows heating oil found seeping through the foundation wall in a crawl space. We suspected that a buried oil tank was or had been outside of this foundation wall and that it had leaked through the building foundation.

Further investigation discovered an abandoned heating oil tank buried just outside of this wall, under a driveway.

See INDOOR CLUES TO BURIED OIL TANKS for a detailed discussion of the study of indoor visual clues used to find a buried oil tank at a residential property.



Continue reading at OIL TANK FAILURE RATES or select a topic from the More Reading links shown below.

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Frequently Asked Questions (FAQs) about how to find a buried oil tank

Question: A buried oil tank was on a property 50 years ago - how can we be sure there is no remaining hazard? Can we assume the tank has dissolved away?

Looking at property to purchase. Now heated with gas....has been for over 50 years. Oil tank buried somewhere on property...detectors cannot locate. Can we safely assume tank deteriorated?? Soil samples = no oil contamination thanx - C.T. 2/26/13

Reply: how to decide when enough looking, soil scanning & soil testing for oil tanks and spills are enough to quit?

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem or to get better clues about the history of oil tanks at a property:.

That said, here are some things to consider:

Not I nor anyone with a modicum of sense would promise you, by email, about a property of which we know nothing, that your site is free of risk of an expensive clenaup job due to a prior oil tank leak or spill based on the information in your note.

If you have reason to believe that an oil tank was previously at the property I would not assume that there was no leak or no remains of an old tank just because no one has seen anything.

With all of these dire warnings the question really is how much time, effort, and money are appropriate to pour into the ground trying to reduce risk of a hidden hazard.

Typically for a site that we know something about, people do soil testing in the most-likely tank locations and, absent any other data, for a residential property they give up, accepting the risk of buried hazards and future costs. It makes sense to think that no one in their right mind would install a buried oil tank at some great distance away from the building it serves, but indeed sometimes tanks are more distant than one might guess.

I have, for example, wandered in the woods of a property being bought by a friend; we found a large above ground oil tank hidden way back in the woods - from years ago; happly there was no leakage. Worse, a buried steel tank, if not properly abandoned, could have been left empty and could lead to a sudden soil collapse, evenĀ  someone falling into the hole - with serious consequences. That tank was nowhwere near any existing building, but we found the remains of an old building - just the foundation that the tank had served. In fact it was the site history, signs of an abandoned road through the woods, and the discovery of the old foundtion that led me to the oil tank.

Remember that if you buy a property and do not find an oil spill, and if you are later selling the property and your new buyer finds a spill, it becomes your cost bear.

For a site where people have reason to be extra careful or concerned (there are factors that can raise our Fear-o-Meter or lower it) other options are available including consulting with an environmental expert who will audit site history, do a records search, and who might use ground scanning radar or other methods to make a more accurate search of the property, ending with a report that either found something or makes thje property owners comfortable.

Also see the FEAR-O-METER a promotion theory to convert risk of hidden defects & hazards into action thresholds, for a discussion of how an accumulation of inspection evidence leads to a rational decision to perform invasive or desctructive inspection measures.

You probably want some combination of research into site history, visual inspection, and testing to decide how much risk remains to you. But if we knew that there had been a buried tank at a property, or were pretty sure there was one that had not been professionally abandoned, presuming it magically disappeared with no work on anybody's part is a bit of a risky proposition.

In sum, when do we quit looking for a buried hazard? Armed with the information you have or can find out, and the extent of property that remains unexplored, and the probability that a buried oil tank was actually installed at some remote spot not near any building, you will decide how much remaining risk there is and and how much to spend on reducing that risk (you can't get it to zero in some cases). That's for you to decide with some advice from an on-site expert.

Reade follow-up:

Thanx....just had it inspected..
No tank,no soil contamination


good news

be sure to keep documentation - in the event of a future property sale that will help.

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