Moler Street Overflow Interceptor Sewer

For decades, heavy rainfall overwhelmed Columbus’s combined sewer system, causing untreated overflows into the Scioto River and flooding nearby neighborhoods. The City of Columbus partnered with CHA to design a long-term solution to address one of the city’s most persistent combined sewer overflow (CSO) points.

At the core of the project is a 96-inch-diameter interceptor sewer installed deep beneath Moler Street. The system redirects excess flow into the city’s underground Olentangy-Scioto Interceptor Sewer Augmentation and Relief Sewer (OARS) tunnel system, where it can be safely stored and treated. CHA used trenchless construction methods to build the tunnel entirely underground, avoiding open excavation that would have disrupted homes, businesses, and two active rail lines above. Engineers also navigated complex soil and groundwater conditions, drilling more than 60 feet down between two aquifers without disturbing them.

This project has eliminated sewer overflows into the Scioto River, improved water quality, and reduced flooding for residents.