Sanitary Sewer Overflows
What is a Sanitary Sewer Overflow (SSO)?
An SSO is a release of untreated or partially treated sewage from the public sanitary sewer collection system. When caused by rainfall, it is also known as a wet weather overflow.
SSOs occur for a variety of reasons, including:
- Accumulation of FOG (Fats, Oils, and Grease), solid materials, or roots within sewer lines
- Defects in sewer pipelines, service lines, and manholes
- Undersized sanitary sewer lines
- Misaligned joints
- Collapse of sewer main lines
- Illegal dumping of solids and chemicals
What to do if you see a marked SSO
Avoid areas where green safety cones, ribbon, or caution signs are posted to indicate an overflow has occurred.
Dry vs. Wet Weather SSOs
Dry weather overflows are usually caused by blockages in the pipe, such as FOG (fats, oils, and grease) buildup, roots, etc. We have the capability of stopping these overflows through mechanical abatement action.
You can help prevent dry weather SSOs by disposing of FOG in the trash, never down the drain.
Wet weather overflows occur because the system is inundated with rainwater, or I&I (Inflow & Infiltration), that is beyond the carrying capacity of the line segments where the overflow is occurring. No mechanical means can prevent or stop a wet weather overflow.
You can help prevent wet weather SSOs by making sure your cleanout is properly capped and repairing damaged private sewer lines.