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 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.