Construction Begins on US$1 Billion Ohio River Sewer Tunnel Project

en.Wedoany.com Reported - On October 22, the Allegheny County Sanitary Authority (ALCOSAN) of Pennsylvania, USA, announced the official start of construction on the Ohio River sewer tunnel project. The project has a total length of approximately 7.9 km and is being built by the Steel City Tunnel Partners joint venture, under a construction contract previously awarded at approximately US$1 billion. The tunnel will collect combined sewer overflows during rainfall and convey them to the existing wastewater treatment plant, with construction scheduled for completion by the end of 2032.

The project is located in the Pittsburgh area and includes a main tunnel approximately 6.1 km long with an internal diameter of about 5.5 m, as well as branch tunnels connecting the Saw Mill Run and Chartiers Creek watersheds. The main tunnel extends from Pittsburgh's North Shore to the ALCOSAN wastewater treatment plant, at a depth of approximately 37 to 46 m below ground. The project will also construct construction shafts, sewage diversion structures, and near-surface ancillary facilities, with a total of 8 construction sites, 6 of which are within the City of Pittsburgh and 2 in the McKees Rocks area.

The contractor Steel City Tunnel Partners is a joint venture owned 50/50 by The Lane Construction Corporation and Brayman Construction Corporation, responsible for the tunnel, shafts, and related underground works. Following the groundbreaking ceremony held on October 22, the project will advance excavation of the first construction shafts to create conditions for the tunnel boring machine, which is scheduled to mobilize in late 2027. The project was previously awarded the contract in April 2026 and received the formal notice to proceed on June 1; this marks the on-site construction start milestone.

The Ohio River Tunnel is the first project in ALCOSAN's regional sewer tunnel system, with the Allegheny River Tunnel and Monongahela River Tunnel also planned for future construction. The system will collect combined sewer overflows during storms through deep tunnels and, together with a new wet-weather pump station, convey them to the wastewater treatment plant. According to ALCOSAN's overall remediation goals, the related infrastructure upgrades are planned to reduce sewage overflows by approximately 7 billion gallons per year.