Breakthrough for US tunnel project

By Andy Brown17 April 2020

Despite the impact of COVID-19 a milestone is reported to have been reached on the Northeast Boundary Tunnel (NEBT) environmental protection project in Washington, D.C., US.

NEBT Break-Through - April 2020 3 (1)

Progress has been made on the Northeast Boundary Tunnel

The contractor Salini Impregilo (Webuild) and its US subsidiary Lane Construction report that a breakthrough by a tunnel boring machine (TBM) means that 60% of the excavation work has been completed despite the Coronavirus emergency.

Salini Impregilo says that they have adopted extraordinary safety measures at its construction sites throughout the world in order to be able to keep them open. The sites include the one in Washington, D.C. and 46 others across the US.

The NEBT, a US$580 million project part of the Clean Rivers Project of DC Water, is the tunnel that will improve the water quality of the Anacostia River by increasing the capacity of the existing sewer system to manage flooding during heavy rainstorms.

“To date, the portion of the Anacostia River Tunnel that is in service has prevented more than seven billion gallons of combined sewage and 3,500 tons of trash from entering the Anacostia, bringing a resurgence to the waterfront,” said David L. Gadis, CEO and General Manager of DC Water.

“The Northeast Boundary Tunnel in particular will significantly reduce sewer backups and chronic flooding in the Bloomingdale and LeDroit Park and other neighborhoods adjacent to Rhode Island Ave, NE.” 

With the breakthrough, the TBM has reached the W Street shaft, the only in-line shaft that it will cross during its 8.2km journey underneath the US capital. The tunnel, with a 7m diameter, goes from the Robert F. Kennedy Stadium at the intersection between Rhode Island Avenue NW and 6th Street NW.

Once connected to the Clean Rivers tunnel network, the NEBT will reduce by 98% the volume of untreated water that would otherwise flow into the Anacostia River.

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