Washington Department of Ecology

State of Washington Department of Ecology

The Washington Department of Ecology does not regulate the use or operation of residential heating oil tanks, like the State of Oregon does. However, some local governments may have different requirements or guidelines that may apply to residential storage tanks. Regulations and policies vary from place to place and may change from time to time.

Are there specific concerns I should have as a homeowner if I have an abandoned oil tank on my property?

  • Tanks can develop holes and release heating oil into the soil. The released oil can contaminate groundwater, surface water, storm sewers, and cause vapor problems in nearby buildings. Under the state Model Toxics Control Act, the tank owner may be held liable for damage caused by a leaking tank.
  • Corrosion can cause underground tanks to deteriorate, making cave-ins a possibility. The homeowner could be held liable for injuries caused by a cave-in.
  • Before finalizing the sale of a house, lending institutions and home buyers may want sellers to remove or “close” unused heating oil tanks. To “close” a heating oil tank, the homeowner has the tank cleaned out and filled. The tank is then left buried in the ground.
Washington Department of Ecology

Washington Department of Ecology – tank found within a backyard in Vancouver, vent pipe can be found running along the side of the house to the left of the window. The sampling of this tank resulted in a Risk Based Clean-Up.

How does Ecology prefer decommissioning take place?

Ecology recommends that the tank is removed with proper soil samples taken, and remediation, if necessary. However, decommissioning the tank in-place is also acceptable, as long as soil samples take place and remediation is completed, if necessary.

Can I decommission my tank as a homeowner?

There is no law prohibiting homeowners from doing their own decommissioning. Although, Ecology does not recommend doing the tank work yourself because of the potential safety risks. Hiring an experienced contractor is advised, as working on an underground storage tank can be dangerous. Under certain conditions, tanks can explode. Working in the excavation pit, cutting open or handling heavy tanks, and using power equipment also pose risks to the homeowner. Ecology recommends that homeowners hire an experienced contractor to perform decommissioning work.

Leaking tanks and the State of Washington Department of Ecology

What if a tank has leaked?

Knowingly using a leaking tank is negligence. If you discover that your tank is leaking you must take immediate action to stop the leak. In most cases where a tank has leaked, only the soil near the tank is affected. Sometimes, however, the heating oil may also have contaminated groundwater or surface water. It is the homeowners or contractors responsibility to:

  • Evaluate the extent of contamination caused by the leak
  • Evaluate the extent of the contamination caused by the leak
  • Determine if it is a threat to human health and the environment
  • Clean-up any contamination caused by the leak

Should I report the leak to Ecology?

Minor Leaks or Spills that affect only the soil near the residential heating oil tank do not have to reported to the Department of Ecology.   However, if the minor leak was discovered during the process of the tank being decommissioned, Ecology does recommend reporting the minor spill through the ERTS program.

Contaminated Soil above 2000 PPM does need to be reported to the Department of Ecology. Any groundwater, surface water, free product or vapor intrusion should also be noted during the reporting process.

How do I report a leak to Ecology?

All confirmed releases must be reported to the Washington Department of Ecology within 24 hours to the ERTS SYSTEM. A leak can be reported via a phone call or through the online reporting system.

Should I clean-up contamination?

Absolutely, and the Department of Ecology recommends that homeowners hire a qualified clean-up contractor to perform the remediation. When the clean-up has been completed, the contractor should give the homeowner a copy of the clean-up report. Clean-up reports of minor leaks do not need to be sent to Ecology, as they do not track or report on these clean-ups. Clean-up reports on more extensive leaks do need to be sent to the Ecology regional office, as they do keep track of and report on these sites. All reports should be kept by the homeowner for their records and the remaining life of the property.

Does the Department of Ecology have a LUST list like the State of Oregon?

Yes, it is called the Confirmed and Suspected Contaminated Site List (CSCSL). However, the majority of the sites on this list are large properties, with larger leaks (i.e. gas stations). It is extremely rare when a residential property does appear on this list, reasons that a site would appear on CSCSL is as follows:

  • When a property has been reported, but after 90 days, no closure and/or continued work to complete the remediation has taken place.
  • If groundwater has been encountered, the property automatically gets put on the CSCSL. The homeowner/contractor then has to go through the voluntary clean-up to get taken off the list. Ecology then works with the homeowner/contractor to get off the list by providing opinions on the work being completed and to verify if meets the status of no further action.

Additional Website Links:

UST Tank Search for Buyers

UST Tank Search for Buyers – Common Questions

As a Buyer, searching for an underground storage tank has become integrated as part of the inspection period. These are some of the most common questions that we are asked regarding the tank inspection process and why it is important to protect yourself before you buy.

What is an underground storage tank (UST)?

Homes, apartments, farms and some businesses that are currently or were previously heated using diesel heating oil, used an underground storage tank (UST) to store the heating oil. The USTs were usually buried in the yard, and copper tubing or steel piping was installed to deliver the diesel from the tank to the furnace. In Oregon, an estimated 100,000 USTs were installed for home heating.

UST Tank Search for Buyers

UST Tank Search for Buyers – Rendition of an underground storage tank (UST) buried in a yard, with the supply lines running into the home.

Why should I worry about a UST?

Underground storage tanks are made of steel, which are selected for their strength, not for their corrosion resistance. Therefore steel USTs rust through, given enough time. Like a roof, steel storage tanks have a life of about 25 years, and like a roof it is cheaper to replace the tank or convert to another heat source before it leaks and the damage is done.

UST Tank Search for Buyers

UST Tank Search for Buyers – Removed tank with numerous holes, this allows the diesel fuel to leak into the surrounding soil.

Performing the UST tank search

How do you find an abandoned UST?

The best way to determine if there is an abandoned oil tank on the property, is to conduct a tank search.

How do you perform a tank search?

EcoTech first will perform a Tank Background Search, this entails a detailed examination of state and local databases, as applicable. Besides years of on-the-job experience, our technician conducts a visual inspection for product lines and fill or vent pipes, utilizes metal detectors and Terra, our specially trained Petroleum Detection K-9.

UST Tank Search for Buyers

UST Tank Search for Buyers – Terra finds a tank

UST Tank Search for Buyers

UST Tank Search for Buyers – The UST Terra found during the tank search, is now marked out for sampling.

What if there is an in-service tank already on the property, should I still do a tank search?

EcoTech highly recommends doing a tank search to rule out any additional tanks that may or may not be on the property. On average our tank searches cost $99.00, during the inspection period this is money well invested. Not only does a tank search give you peace of mind that there are no additional tanks on the property. It can also save you from years of worry or money spent if there is indeed an additional leaking tank on the property, which you now own and are responsible for cleaning up.


UST Soil Sampling

UST Soil Sampling Common Questions

Whether a tank search has resulted in a UST being discovered or if there is an in-service tank on the property, EcoTech highly recommends soil sampling be completed around the tank.

If you are a buyer, it is imperative for you to obtain soil samples on the underground storage tank, as once you purchase the property, you have now purchased the UST and if it is leaking, are now responsible for the clean-up.

If you are a seller or a homeowner thinking about selling, and you know you have an UST on your property, preemptive soil samples will allow you prepare for pre-inspection complications.

For more information on underground storage tanks and real estate transactions, please see the DEQ Buying or Selling guide for helpful tips DEQs Buying or Selling a Home with a UST

What if a UST is found?

Soil Samples are recommended. Per Oregon DEQ, the best way to determine if a UST has leaked, is to have soil samples collected from under each end of the tank and have the samples analyzed for diesel and heavy oil. Each sample should be analyzed at an independent laboratory that is DEQ certified.

UST Soil Sampling

UST Soil Sampling – Rendition of technician taking soil samples 12-24″ beneath an underground storage tank.

UST Soil Sampling

UST Soil Sampling – Sampling tubes filled with soil from around an underground storage tank. The soil is then placed in a jar and sent to the lab for testing.

There is an in-service tank, should I perform soil samples?

As a prospective buyer, it is essential to test a tank before purchasing the property to determine if it has leaked or is currently leaking. The current property owner is responsible for any necessary contamination clean-up from a leaking underground storage tank. Purchasing a property without testing a tank makes you, as the new property owner, liable for a prior or currently leaking UST.

I’m selling my home and the buyer has found a tank, what are the next steps for me?

EcoTech recommends that you decommission the tank and register it with DEQ. Although, through our experience, buyers and their agents will require at a minimum proof of clean soil samples.

Types of Soil Samples

What are the type of UST soil samples? 

There are three different categories that sample results can be placed into:

Non-Detect (ND)

In-service tank: samples that were analyzed have come back as non-detect and no further tests are necessary. EcoTech does recommend that the decades old tank be decommissioned and a new heat source chosen, as soon as it is practical, before the tank does leak.

Out-of-service tanks: samples that were analyzed have come back as non-detect and no further tests are necessary. EcoTech does recommend that the out-of-service tank be decommissioned within 90 days of the soil samples and registered with DEQ.

*For both the in-service and out-of-service non-detect samples that were taken from each end of the UST, does not rule out the possibility of contamination underneath the soils of the tank, that is why EcoTech recommends decommissioning of the UST.*

50 PPM (parts per million) or less

In-service tank: samples that were analyzed indicate that a leak is present. Although this is a low detection and it is not reportable to DEQ, it indicates a leak has started and should be a concern. EcoTech highly recommends that the tank be taken out-of-service and decommissioned and registered with the DEQ.

Out-of-service tank: samples that were analyzed indicate that a leak is present. Although this is a low detection and it is not reportable to DEQ, it indicates a leak has started and should be a concern. EcoTech recommends that the out-of-service tank be decommissioned and registered with DEQ.

50.1 PPM or Greater

In-service or out-of-service tanks: “The OR DEQ requires that any site where a soil sample analysis shows petroleum concentrations of 50 PPM or greater, must be reported to the DEQ within 72 hours. Remediation will be determined based on the extent of the contamination.” Simply put, the tank is leaking above the reporting limit, EcoTech is required to report the leak to the DEQ, corrective action is now needed to clean-up the site.