Underground Home Fuel Tank Decommissioning

Tank Exposed

A leaking tank can cause several serious problems for the owner and others, such as:

  • Contamination of the soil on the primary and adjacent properties;
  • Contamination of groundwater, which may serve as a source of drinking water;
  • Contamination of surface waters;
  • Vapor accumulation under or in nearby buildings;
  • Collapse of old or unused underground heating oil tanks causing sinkholes.


Property owners can be found liable for contamination caused by a leaking tank. In fact, past or present ownership of contaminated property may result in liability. Because of this threat of liability, many lending institutions and buyers require decommissioning of unused heating oil tanks before they will finalize a property sale. In addition, delaying the cleanup of any contamination may allow contaminants to spread, potentially increasing cleanup costs. Therefore, it’s generally in the best interest of an owner to remove or decommission an unused home heating oil tank and if leakage is present, report and remediate it immediately.

Remove or Abandon in Place?

Tank Removal:

Pump the fuel from the tank; obtain a DMO permit from the City of Vancouver and remove the tank and all piping. Call for a Fire Marshal inspection prior to filling the hole with soil. It is the responsibility of the property owner or permit holder to have the soil tested to document that there was no leakage. This will be important if you ever wish to sell the property. Note: Removing the tank is sometimes a condition of sale by lending institutions or buyers.

Tank Abandonment:

Pump the fuel from the tank; obtain a DMO permit from the City of Vancouver. Expose the surface of the tank and cut an adequate opening to provide for residue cleaning.

WARNING: Use an atmospheric monitor to insure that there are no explosive fumes in the tank when using tools to cut into it. Use approved respiratory, skin and eye protection. Reputable tank decommissioning contractors will inert the tank atmosphere before cutting into the tank.

Clean the inside of the tank and any piping to be left underground until there is no residual fuel. Professionals refer to this cleaning as "triple wash". Dispose of all residual fuel and contaminated water as hazardous materials.

The suction, inlet, gauge, vapor return and vapor lines must be disconnected. All remaining underground piping must be capped, plugged or removed. All above-grade piping shall be removed.

Call for a Fire Marshal Inspection. If there is a delay for inspection please temporarily cover the opening so that children and animals cannot fall into it.

Fill the tank with an approved solid inert material and call for a second and final Fire Marshal inspection prior to covering with soil.

Is a Soils Test required?

Per WAC 173-340-300:
Release report.
Any owner or operator who has information that a hazardous substance has been released to the environment at the owner or operator's facility and may be a threat to human health or the environment shall report such information to the department within ninety days of discovery. Releases from underground storage tanks shall be reported by the owner or operator of the underground storage tank within twenty-four hours of release confirmation, in accordance with WAC 173-340-450. A soils test will inform the Pollution Liability Insurance Agency what cleanup standards, if any, apply to your situation.


  1. Take and retain photos of each stage of the process
  2. Keep a copy of the approved permit from the City.
  3. Keep a copy of the contractor’s decommissioning report.
  4. If the tank was close to the foundation, obtain a fill compaction report to document due diligence in protecting the foundation’s integrity.
  5. If soil contamination is detected, keep documentation of remedial actions taken. If no soil contamination is detected, keep that documentation as well as it can be very important at the time of property sale.
  6. Keep all records in a permanent location in the building.
Tank Removed
Tank Opened
Tank Cleaned
Leave it to the professionals