Many older homes in Seattle and other cities still have oil heat or had oil heat at one time in the past before they converted to natural gas or electric heat. If you are buying a home that currently has oil heat, you will still be using the underground oil tank to provide fuel for your furnace. However, the home you are buying (or selling) may have an abandoned underground storage tank. Unused underground oil tanks should be decommissioned or removed to prevent oil contamination of the surrounding soil and ground water. Underground oil tanks could also corrode and collapse, creating a sink hole in the yard.
Is there an underground oil tank?
How do you find out if your property has an underground oil tank? Many times there are obvious clues in the basement near the furnace. There may be old oil lines that have been cut, but still stick out of the wall or floor. You may also see oil staining around the furnace area or other indications that the home once had oil heat. Sometimes you may also be able to see a fill cap in your yard somewhere.
If you think there is an oil tank in the yard, but do not know where it is located, there are oil tank removal companies that can survey the yard and help you find it. If the fill/vent cap is buried, they can use a metal detector to find it. If the fill cap has been removed, a larger, more sophisticated metal detector can help find it.
Has the oil tank been decommissioned?
In Seattle, oil tank decommissioning has been done under permits from the Seattle Fire Department since 1997. You can search for oil tank decommissioning permits on their website. Prior to 1997, permits were not required, so you would have to consult with the current homeowner for any records of the oil tank being decommissioned.
Decommissioning options for underground oil tanks
Discovering an abandoned oil tank on your property does not mean that it has leaked or caused environmental problems, but the potential is certainly there. Often oil tanks have been abandoned with a considerable amount of heating oil remaining in the tank, so emptying the oil and dealing with your tank now can help prevent future problems and expense. If the tank has leaked, the Washington Department of Ecology does have reporting requirements based on the extent of the contamination found, and owners can be responsible for cleanup of soil surrounding the tank.
Here are the options for decommissioning an underground oil tank:
- Complete Tank Removal – Excavating and removing the tank is the most expensive option, but allows visual inspection of the soil surrounding the tank and more accurate soil testing. This can be a major hassle if the tank is located underneath concrete patios, walkways or decks.
- Foam Fill – The oil tank is drained and rinsed and then is filled with polyurethane foam. The foam is inert and maintains the shape of the tank to prevent any future tank collapses.
- Slurry Fill – The oil tank is drained and rinsed and then is filled with a lightweight concrete slurry. This prevents future tank collapses, but if the tank ever needed to be removed, the added weight of the concrete will require a crane to lift it out of the ground.
- Pump/Clean/Cap – The oil tank is drained, rinsed and capped, but left empty. This is the least expensive option, but it does leave open the possibility that a tank make corrode and collapse, creating a sink hole in the yard and potentially affecting nearby structures.
What if my oil tank is still in use?
Oil tanks that are still in use can also leak and cause problems. There is actually a great liability insurance program run by the state of Washington that is funded by a fee that oil dealers pay when they sell heating oil. The insurance program will help cover cleanup costs caused by an oil tank, but homeowners must register with them before the leak occurs to be eligible for benefits. This is a no-brainer if you have have an active oil tank in your yard. Instructions on how to register for the Heating Oil Pollution Liability Insurance Program can be found here. Keep in mind that you need to re-register if you buy a home. The coverage does not automatically transfer to the new owner.
Oil Tank Advice for Home Buyers and Home Sellers
Here are the key things to remember if you are selling or buying an older home that may have an oil tank:
- Home Sellers –If you home has an abandoned oil tank, make sure it is decommissioned before you sell the home and be prepared to provide documentation the buyer.
- Home Buyers – If you suspect that a home has an abandoned oil tank, request that the seller properly decommission the tank to avoid potential future problems and expense. If you suspect that the tank may be leaking into the soil, soil tests around the tank will be needed to test for any contamination.
- Home owners with oil heat – Make sure you are currently registered with the Heating Oil Liability Insurance Program, which will defray cleanup costs if you have an oil tank leak in the future.