This page lists the basic information of what a real estate agent in the Portland, OR area should know about heating oil tanks.

Heating Oil Tanks are old steel containers which are often buried underground, they are filled with diesel fuel which is or was used to heat many home. These tanks were installed in homes from the 1930s to the 1970s.

A large amount of these tanks rusted and leaked number 2 oil, aka diesel, into the surrounding soil. It typically costs between $1,000-$3,000 to clean up an oil tank spill. In the case of very bad leaks the cost can easily meet or sometimes exceed $10,000.

The cost of a cleanup depends on how much oil leaked into the ground, how much physical space it takes up, and if there is groundwater. The DEQ will let you leave up to 65 cubic yards of contaminated soil that is under 10,000ppm. More than that and the tank and dirt under it usually needs to come out.

Some homes have more than one underground storage tank. Such as for a garage, for gasoline, a duplex, or a previous underground tank failed and was not removed at that time.

Because of this it is advised to get a tank search in any neighborhood that existed prior to the 1980s. Even if there is a letter of decommissioning there can still be a second tank if no one has searched for one.

So you’ve got an oil tank.

What buyers want is a letter of decommissioning which has been certified by the DEQ. In order to get this the tank needs to meet some requirements. If a tank is found during the inspection process a buyer should ask the seller to get the DEQ certification.

When work is done correctly on a tank, and it is the only tank on the property, then that work can be approved by the DEQ and the clients are happy. If there was never a tank then there is nothing to worry about, but a removed tank without a certification can in theory still have contaminated soil. If a tank was removed but there are no records of soil samples or decommissioning then the area where a tank was removed from should be sampled.

Petroleum Contaminated Soil can spread farther if groundwater is present. If oil leeches into the soil and gets under the home it can off-gas into unhealthy chemicals (tolulene, xylene, benzene, ethyl-benzene, POCs, PAHs) and those inside the home can breath these chemicals.

If soil samples are tanken and the soil is contaminated it goes to a Leaking Underground Storage Tank list, called the LUST. If soil samples are taken but didn’t leak then the DEQ doesn’t report.

If someone takes clean samples and submits a file to the DEQ and pays a filing fee then it will be listed on a Voluntary Certification, List of Intact Storage Tanks, called the LIST. This means someone can do work correctly and not pay the filing fee and there are no public records with the DEQ. One would need to file a public record request with the DEQ to obtain any records regarding what information they have on this.

If a tank is or was present, and no DEQ certification can be found then one must be produced. This usually means taking new soil samples, verifying that the decommission was done correctly by digging up part of the tank, and filing the report.

Radon Info

Radon is present in the Willamette Valley and along the Columbia river area, typically up to an elevation of not more than 400′. The radon comes out of Uranium which is present in granite which was deposited here during the Missoula floods.

Some homes can have high radon while other nearby homes have low radon due to the dispersal of these rocks. Radon levels also naturally peak in the winter and are lowest in the summer. You can read the radon page to find more detailed information.

This airborne element comes out of the ground constantly, but doesn’t stay around long. It can move through concrete, plastic, wood, etc. Homes that ‘breathe’ more in the crawlspace or basement will have lower radon level.

To lower radon levels a vapor reduction device is added which draws air from either the crawlspace or from below the basement slab and pumps it out above the roof. This stops it from accumulating inside the home and therefore people living in the home aren’t breathing as much radon.

To test for radon levels a machine is set up in the home for at least 2 days to get a good reading. The results are giving in units of radon per liter of air. In the EU the recommendation is to install a radon reduction system at 2 mPi/L. In the USA the EPA lists 4 as their action limit.