This tank was in-use immediately before removal. Note the large holes and oil staining the bottom of the tank.
At some properties an oil furnace is currently being used to heat the house. There are three tank history possibilities for these properties:
the furnace is still using the original underground oil tank,
the original underground oil tank had a problem (leak) and was replaced by a second underground oil tank or by an above ground tank, or
the home had always used an above ground oil tank to supply fuel to the oil furnace.
1) The original underground tank is still in-use:
This is usually the case. Typically, these houses were built in the 1950's and 1960's (or prior) and are still using the original underground oil tank to heat the house. This means that these bare steel tanks have been in the ground corroding for 50 to 60 years. This is well past the 15 to 20 year life expectancy for this type of tank.
Usually leaking in-use tanks have larger and / or more severe contamination problems. These tanks have probably been leaking for many years and are filled each year to allow the leak to continue.
Since January 2005, PES has documented a 100% leak rate for in-use tanks (tanks being used at the time of removal).
Sellers may mistakenly view these in-use tanks as an asset to the property because they are currently being used to store fuel for an operational oil furnace and no leak is apparent. Unfortunately, there is no good way for a home owner to accurately monitor the integrity of the tank.
If the tank leaked 2 gallons a month for five years, this releases 120 gallons of fuel into the environment significantly contaminating the property. (For common size tank, a 2 gallon leak may only be a one tenth of an inch drop in fuel level. This level change would be very difficult to observe even using a dip stick.)
Above ground tanks are usually installed after the underground tank fails.
Solution: Remove the tank and conduct a proper assessment to document the contamination status of the property. At a minimum, it is time to upgrade the tank. See our Tank Closure Page.
Soil sample can be taken beside in-use tanks to help determine if a leak has occurred. However, this sampling method is not conclusive. If a release is discovered, the property owner will have to report the release, immediately stop using the tank, and proceed with tank removal and contamination cleanup.
2) The original underground oil tank had a problem (leak) and was replaced by a second underground oil tank or by an above ground tank.
If the in-use tank is not the original tank, chances are that the original tank had a problem (it leaked) and was replaced by the second underground or by an above ground oil tank. Why else would someone replace a perfectly working tank with a new tank?
Solution: Contamination is almost guaranteed. The tank should be removed and thoroughly assessed to document the contamination status of the property. Please see our Tank Closure Page.
3) The home always used an above ground oil tank to supply fuel to the oil furnace.
This is unlikely for in-town, developed neighborhood properties. While this may be a possible scenario for some rural properties, virtually all furnaces for in-town, developed neighborhood properties were originally supplied by an underground oil tank. Just because the underground tank is not obvious, does not change this fact.
Solution: Have PES conduct a tank search on the property. If the tank was removed earlier without assessment, the tank history will be difficult to determine just from a property inspection. How long do you look for something that is not there and may have never been there? We do recommend that you do "due diligence" to search for a tank for your own protection.