Big Walnut Sanitary Trunk Extension Phase 2

CIP# 650033-100002

The City of Columbus will be constructing this project in order to extend sanitary sewer service further into the northeastern Franklin County service area and the southern Delaware County service area.

The Big Walnut Phase 2 project is an extension of an existing 72-inch sewer that currently terminates near the intersection of Central College Road and Sandimark Place. It will extend this sewer in a northeasterly path to the area just west of the intersection of Smothers Road and Harlem Road. View the map(PDF, 740KB) for a more detailed alignment layout.

Tunnel Boring MachineThe finished diameter for the Trunk sewer will be 72-inches. It will be constructed mainly in the Ohio Shale rock formation utilizing a tunnel boring machine (TBM). The construction will consist of a 2-pass method in which the TBM will cut a larger 108-inch to 120-inch tunnel in the rock that will then have a 72-inch fiberglass reinforced pipe installed within it and grouted into place for sewer conveyance. Hydrogeological and geophysical studies were performed to select the best technology for tunnel construction and to ensure the TBM is designed to operate in a manner that reduces impacts to nearby residents and wells. The tunnel will be constructed at an approximate depth of 180-200 feet below ground.

The project will be advertised for bid and the City will issue the construction Notice to Proceed in early 2023. While the TBM is mining, intermediate shafts will be constructed to provide service for impacted locations during construction. Overall, the entire project is due to be completed by the end of 2026. Traffic impacts are being mitigated through restricted hauling hours and designated hauling routes.

To finance the construction of this project, the City of Columbus will apply for a low interest loan from the Ohio EPA’s Water Pollution Control Loan Fund (WPCLF). The city has requested similar funding for the Blacklick Creek Sanitary Interceptor Sewer and many other Capital Improvements Projects in the past.

Ohio EPA has issued a Final Finding of No Significant Impact for the City of Columbus, Department of Public Utilities’ Big Walnut Trunk Extension, Phase 2 project (CIP# 650033-100002; WPCLF Loan Number CS390274-0396). View the Final Finding of No Significant Impact.(PDF, 523KB)

For questions regarding this project - contact city Project Manager, Rob Herr, at