The second TBM for DC Water’s Potomac River Tunnel Project arrived at the West Potomac Park construction site yesterday.
TBM Emily, an earth pressure balance machine, will dig south towards Joint Base Anacostia-Bolling.
TBM Mary[https://www.tunnelsandtunnelling.com/news/tunnelling-commences-for-potomac-river-tunnel/] was launched in April and is excavating north toward Georgetown. The two machines were built for different ground conditions: Mary for harder rock on the approximately 3.87km northern stretch, and Emily for softer soils and mixed ground on the 5km southern stretch.
“Emily’s arrival brings the scale and importance of this project into focus. With both tunnel boring machines now on site, we have the final piece needed to build the Potomac River Tunnel,” said DC Water CEO and general manager David L Gadis. “Soon, Emily will be underground helping advance a project that will protect the Potomac River, reduce pollution and serve the District for generations to come.”
The Potomac River Tunnel, being delivered by CBNA-Halmar Clean Rivers JV, comprising CBNA, Halmar, COWI, and Hatch, is part of DC Water’s Clean Rivers Programme, a long-term initiative to reduce pollution in the District’s waterways. Once complete, the tunnel will capture and redirect combined sewer overflow to the Blue Plains Advanced Wastewater Treatment Plant. The project is expected to reduce combined sewer overflows from about 74 events per year to four in a typical year and cut overflow volume by 93%.
