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: