The contract is worth US$254 (£163m), with Impregilo operating as the project’s leader and taking a 65% stake. It will coordinate the works with Parsons and its US subsidiary Healy, which specialises in underground projects.
The Anacostia River Tunnel scheme is part of DC Water’s Clean Rivers project. It involves construction of a tunnel that will run for most part under the Anacostia River, a tributary of the Potomac. The tunnel will have a length of 3.8km, an inner diameter of 7m and six water collection wells each with a depth of approximately 30m. The tunnel will collect and convey separately wastewater and rainfall, thereby avoiding river pollution caused by combined sewer overflows that occur during intense rains.
Work is expected to take approximately four and a half years.