First Major Construction Activity Begins For Potomac River Tunnel

Starting on or about June 17, 2024, DC Water‘s contractor for the Potomac River Tunnel (PRT) Project (CBNA/Halmar JV) will temporarily close a section of Ohio Drive, SW. The main construction site in West Potomac Park will be active until the project’s completion in 2030. A relocated Ohio Drive will direct traffic around the construction area.

The Potomac River Tunnel (PRT) is the next major phase of the DC Clean Rivers Project, which is DC Water’s ongoing program to reduce combined sewer overflows (CSOs) into the District’s waterways. The project consists of a large-diameter deep sewer tunnel, diversion facilities, drop shafts, and support structures to capture flows from existing CSOs along the Potomac River and convey them to the Blue Plains Advanced Wastewater Treatment Plant.

“This project is critical to ensure we reduce the CSOs that contribute to water quality impairment of the Potomac River and the Chesapeake Bay,” states David L. Gadis, DC Water CEO and General Manager. “So while the construction could be disruptive, and we will try to minimize the traffic impacts, ultimately, the tunnel will improve the resilience of the District against the threat of pollution and climate change for generations to come.”

The 18-foot-diameter tunnel will run deep underground beneath the Georgetown waterfront, along the edge of the National Mall and East Potomac Park, past Hains Point, and connect by gravity to the existing Anacostia River Tunnel. Construction will require two tunnel boring machines (TBMs). Starting from West Potomac Park, one TBM will mine south through mostly soft ground, and another TBM will head north to bore through rock.

The roadway that will serve as the relocation of Ohio Drive will be constructed beginning June 17 and is expected to open by October 2024, weather permitting. Until then, traffic will be detoured, and signage will be in place to assist motorists and cyclists with navigating the construction zone safely. Additionally, signage will be in place to help pedestrians with temporary sidewalk closures on Independence Avenue, SW, and adjacent to the West Potomac Park construction site. When the relocated Ohio Drive opens in October, it will remain in place until the project’s completion in 2030. It will be restored to its original route.

The PRT 2030 completion date is stipulated in the Consent Decree DC Water signed in 2005 with the U.S. Environmental Protection Agency, the Department of Justice, and the District of Columbia. Once the PRT is operational, it will reduce CSOs to the Potomac River by 93 percent in an average year of rainfall. CSOs impair water quality by increasing water bacteria levels, which negatively impacts aquatic life, and contributes to an increase in the amount of trash in waterways. An estimated 654 million gallons of CSOs enter the Potomac River each year by average rainfall.

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