The South Side Flats Sewer Rehabilitation Project used a novel method known as trenchless sewer installation or “sewer microtunneling” to help minimize disruptions to residents, avoiding the need to dig up the entire street surface.

Sewer separation projects, such as the one in the South Side Flats, also play a critical role
in improving water quality and safeguarding
public health.

Across approximately 75 percent of Pittsburgh, wastewater and stormwater are routed into the same underground sewer pipes; these are referred to as combined sewers. Combined sewers carry both wastewater and stormwater simultaneously to a sewage treatment facility. In relatively dry weather this works fine. During heavy rains, however, excess stormwater can overwhelm the capacity of the pipes, causing some of the combined stormwater and sewage to overflow into the rivers at sewer outfalls and in some cases contributing to basement backups.

This is where Municipal Separate Storm Sewer Systems (MS4) tend to help; these separate sewer systems work in parallel, funneling stormwater not into the same pipes as wastewater, but into separate pipes leading straight to our waterways.

Separated systems like these help avoid the health hazards of combined sewer overflows because the wastewater conveyance system remains separate from the pipes carrying stormwater, preventing untreated sewage from entering rivers and streams.

In 2025, we made significant progress on our South Side Flats Sewer Separation Project. This ongoing initiative will result in a modern MS4 system throughout several local streets, reducing the occurrence of combined sewer overflows and protecting the health of our rivers and the neighborhood.

Green infrastructure – like rain gardens, native vegetation, and bioswales – help capture runoff and more slowly release stormwater into the ground and sewer systems. These nature-inspired measures help avoid localized flooding and protect against combined sewer overflows.

Green infrastructure projects, like the Woods Run stormwater management project in Riverview Park, help improve water quality and protect public health and the environment. The Woods Run project will incorporate green stormwater infrastructure to capture runoff, stabilize stream channels, and slowly release stormwater back into the combined sewer system. These measures reduce erosion, park flooding, and combined sewer overflows to the Ohio River.