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:

Generic Remedy Clean-Up

Generic Remedy Clean-Up

A Generic Remedy Clean-Up is considered a mid-level contamination, consisting of a release of 501 – 10,000 PPM. This remediation is a soil-only clean-up as long as there is no impact to groundwater, no free product is present and there is no vapor intrusion into the home or building. A generic remedy may require soil removal, as well as additional soil samples around the tank to determine the extent of the contamination. Total Petroleum Hydrocarbon (TPH) concentrations up to, but not exceeding, 10,000 PPM of soil may be left in place if:

  • There is at least three feet of clean soil over the contaminated soil
  • The volume of remaining contaminated soil (over 500 PPM) does not exceed 65 cubic yards
  • Analysis for the presence of benzene, ethylbenzene and naphthalene must be performed on all samples exceeding 2,500 PPM.
Generic Remedy Clean-Up

Generic Remedy Clean-Up – this is the fill cap from a tank that was decommissioned through a generic remedy remediation. The concrete was cut in order to gain access to the tank underneath the concrete patio.

Generic Remedy Clean-Up

Generic Remedy Clean-Up – Fill material from a tank that was being decommission through generic remedy remediation, this tank was found to have leaked at 5710 PPM

Once the investigation of the soils around the tank and the contaminated soil has been removed, the generic remedy clean-up decommissioning of the tank can continue.

In order to establish if a generic remedy is necessary, the DEQ requires a site assessment must be conducted to determine the source, nature, magnitude and extent of the contamination associated with a release from the underground storage tank. The site assessment must specifically address:

Generic Remedy Clean-Up Investigation

  • Determine the presence of free product
    • If there is pooling of liquid fuel in the tank excavation area or if there is clearly visible saturated soil, free product is present and a generic remedy remediation is no longer acceptable.
  • Determine if groundwater is affected and the depth to groundwater
    • During the tank excavation, if groundwater impact is discovered, the DEQ requires the water be pumped from the pit. If the pit remains dry for 24 hours, sampling and clean-up may proceed under the generic remedy. If water returns in less than 24 hours, it is presumed to be groundwater and the use of the generic remedy remediation is not allowed.
  • Determine the vertical and horizontal extent of the heating oil contamination
    • If decommissioning will be performed by removing the tank, two samples must be taken from each end of the excavation, at least 6 inches below the bottom of the excavation. If, by visual observations, additional contamination or odors are detected, samples must be collected from these areas as well.
    • If the decommissioned tank is to stay within the ground, two soil samples are to be taken from each end of the tank, as well as one below the tank bottom. The samples are to be taken no more than six inches from the tank end and at least one foot below the tank bottom. If contamination or odors are encountered, based on visual observations, samples must also be collected from these areas as well.
    • An estimated volume of contaminated soil proposed to remain at the site will be required to ensure that the 65 cubic yard limitation is not exceeded. Results of soil samples analyzed for the presence of heating oil are required to determine both the vertical and horizontal extent of contamination remaining above 500 PPM.

We have provided a link, this provides more insight to understanding more of the DEQs requirements regarding Generic Remedy Clean-Up remediation standards and guidelines.

Septic Tank Decommissioning

Septic Tank Decommissioning Common Questions

What is a septic tank?

A septic tank processes wastewater from the home and consists of two main parts, the tank and a drain field.  It encompasses a piping connection, allowing the waste to flow from the home, through the tank and into the drain field, these connections are made through a T pipe, allowing liquid to enter and exit without disturbing the surface above.  The septic tank treats the wastewater and allows the separation of solids and liquids, once broken down the solids remain in the tank while the liquids drain into the leach field.

Septic tanks may be concrete or metal, 5 to 7 feet long and 5 to 7 feet deep, and will be located 5 to 30 feet away from the home.

Are there dangers associated with abandoned septic tanks?

Septic tanks that are buried underground are susceptible to corrosion, thus weakening the stability of the structure. The instability can cause the system to collapse, causing serious injury or death. Septic tanks contain dangerous gases due to the breakdown of decomposing matter, falling into a tank can cause the possibility of being overcome by noxious gases.

How do I know if I have a cesspool or septic tank on my property?

Within the Portland Metro area, there are two methods that may help determine if you have a cesspool or septic tank on your property:

  • For a general rule:
    • If your home is east of the Willamette River, most systems installed were cesspools.
    • If your home is west of the Willamette River, most systems installed were septic tanks.

How do you find a septic tank?

The location of the system would need to be determined by sending out a technician to the property.  The technician locates the main plumbing stack that comes through the roof and visually extends a straight line from the exterior foundation line.  From the foundation, the technician would follow the visual straight line out to the septic tank, between 5 to 30 feet from the home.

Decommissioning of a septic tank

How do you decommission a septic tank?

The proper septic tank decommissioning permit will need to be obtained for the city and/or the county the septic system is located in.

EcoTech uses excavation equipment to dig to the top of the structure to expose and open the septic system.  Once accessed and per OSHA regulation, shoring of the area around the system is completed to prevent collapse of the shaft and to ensure the safety of our technicians.

Our technicians will then inspect the interior of the tank, and pump any liquid or sludge that may be present.

Contingent on the city and/or county permitting process, inspection of the system may need to take place prior to filling the tank.  Inspection may also need to take place after the tank has been filled, depending on permit requirements.

When the tank has been pumped of all sludge, and all relevant inspections completed, the tank can be filled with either sand or gravel.  Once the septic tank is decommissioned, the technicians would replace the soil overburden, bringing the area back to surface grade, along with a closed permit for the decommissioned septic tank.

Septic Tank Decommissioning

Septic Tank Decommissioning – Dug down and exposed septic tank

Septic Tank Decommissioning

Septic Tank Decommissioning – Roped off septic pit for safety

Septic Tank Decommissioning

Septic Tank Decommissioning – Broken terracotta pipe, this is part of the system that allows wastewater to drain from the home. When the pipe is broken, this allows waste to seep into the yard.

Septic Tank Decommissioning

Septic Tank Decommissioning – Filled septic tank, with T piping junction of metal pipe to terracotta pipe.

Septic Tank Decommissioning

Septic Tank Decommissioning – Filled septic tank, with T piping junction of metal pipe to terracotta pipe.

Septic Tank Decommissioning

Septic Tank Decommissioning – Filled septic tank, ready for overburden to be replaced

For more information on local cities requirements on septic tank decommissioning within the Portland Metro area, please click on the following links:

Cesspool Decommissioning

Cesspool Decommissioning Common Questions

What is a cesspool?

In the most basic terms a cesspool, it is an underground container for the temporary storage of liquid waste and sewage. The system is made up of loose-fitting brick or stone, which allows the liquids to seep through the stones and into the soil, leaving the solids behind.

Cesspools are usually made from concrete, brick or cement block, are 3 to 4 feet in diameter, and located 10 to 12 feet away from the exterior foundation of the home. Homes without a basement have cesspools typically located about 3 to 5 feet below ground surface and homes with a basement, the top will commonly be 8 to 10 feet below the ground surface.

Why should I worry about a cesspool?

Older abandoned cesspools are cause for concern since the system can become unstable and collapse, causing a sinkhole within the yard. The vulnerability of the design can be severely impacted due to flooding, heavy rains and tree roots. Since cesspools are at a minimum 3’ below the ground surface, falling into a pit which may contain liquids and sludge, can cause serious injury or death.

If you suspect that a sinkhole is forming within your yard, the area should be roped off immediately to prevent anyone from falling into the opening and a qualified expert should be contacted for assistance.

How do you find a cesspool?

The location of the system would need to be determined by sending out a technician to the property.  The technician locates the main plumbing stack that comes through the roof and visually extends a straight line from the exterior foundation line.  From the foundation, the technician would follow the visual straight line out to the cesspool, usually 12′ from the home.  Following the original plumbing and building sewer line is the most reliable way to find the cesspool.

The cesspool will be marked out and an excavation investigation would take place to determine the depth and to determine the contents of the system.

Cesspool

Cesspool marked out for excavation

Decommissioning of a cesspool

How do you decommission a cesspool?

The proper cesspool decommissioning permit will need to be obtained for the city and/or the county the cesspool is located in.

EcoTech uses excavation equipment to dig to the top of the structure to expose and open the cesspool.  Once accessed and per OSHA regulation, shoring of the area around the system is completed to prevent collapse of the shaft and to ensure the safety of our technicians.

Our technicians will then inspect the interior of the cesspool, and pump any liquid or sludge that may be present.

Contingent on the city and/or county permitting process, inspection of the system may need to take place prior to filling the cesspool.  Inspection may also need to take place after the system has been filled, depending on permit requirements.

Once the cesspool has been pumped of all sludge, and all relevant inspections completed, the cesspool can be filled with either sand or gravel.  The cesspool decommissioning has taken place, the technicians would the replace the soil overburden, bringing the area back to surface grade, along with a closed permit for the decommissioned cesspool.

Cesspool Decommissioning

Cesspool Decommissioning – After excavation, shaft shored up for safety to begin decommissioning.

Cesspool Decommissioning

Cesspool Decommissioning – Cesspool has been inspected and the decommissioning can begin.

Cesspool Decommissioning

Cesspool Decommissioning – Completed decommissioned cesspool.

For more information on local cities requirements on cesspool decommissioning within the Portland Metro area, please click on the following links:

Please note: although most of these links will reference septic tanks, the decommissioning processes is relatively similar.