Sanitary Sewer Overflow

Many people don't realize that when it rains, raw, untreated sewage may flow into our rivers and streams.

During wet weather (rain/snow melt) excess water gets into the sanitary sewage system through deteriorated pipes and illegal downspout connections from homes. This additional water exceeds the capacity of the pipes that carry sewage to the Allegheny County Sanitary Authority (ALCOSAN), the regional sewage treatment facility. When this happens, raw sewage overflows into rivers and streams. The federal Clean Water Act requires communities to eliminate and/or control these sewer overflows.

In O'Hara Township, the sanitary sewage collection system is designed to carry wastewater to the treatment plant. Stormwater is carried in a separate system. However, in the 1940's and 50's when most of the sanitary sewage system was constructed, structures called sanitary sewer overflows (SSO's) were built into the system. If the sanitary sewage system receives too much flow, the overflow is discharged from the SSO's into area waterways before it reaches the treatment plant. This prevents overflows of manholes or back ups in homeowners' basements. While SSO's were consistent with environmental standards at the time they were built, the Clean Water Act now deems them unlawful. The Environmental Protection Agency in enforcing the Clean Water Act, will impost large penalties and fines on those communities who fail to eliminate SSO's from their sanitary sewage systems.

All 83 communities served by ALCOSAN, including O'Hara Township, must address the SSO problem. O'Hara is part of the Northern Communities Basin Group which meets regularly to consider the sewer overflow issue. As a result of this cooperation, a cost effective, regional strategy is being developed. As this issue develops, look for more information about what improvements will made to be presented in the O'Hara Newsletter.