Dive brief:
- Washington, D.C.’s $583 million Northeast Boundary Tunnel went into service Friday, the largest segment of a five-part, $2.7 billion system being built under the city to prevent chronic sewer overflows. Connect to a segment that ended in 2018.
- The new tunnel will capture and store overflow from the capital’s century-old sewers and transport it to a treatment facility. It is designed to prevent river pollution during periods of heavy rain and will also reduce flooding in areas north-east of the city, including in Brentwood, where it occurred on 14 August. the flood killed 10 dogs in a pet care business.
- A joint venture of Cheshire, Conn.-based Italian firm Salini Impregilo and Lane Construction built the 27,000-foot-long, 23-foot-diameter structure under a design-build contract, with design and engineering work by Denver-based Brierley Associates.
Diving knowledge:
The tunnel is part of the Clean Rivers project, which grew out of a lawsuit that environmental groups filed in 2000 against the District of Columbia Water and Sewer Authority for allowing billions of gallons of sewage untreated flow into the area’s rivers. Construction of the global tunnel system, which stretches around 12 miles, began in 2011. The new segment began in 2018.
The addition of the latter tunnel is designed to prevent 98% of sewer spills and is an important step toward the restoration of the Anacostia River. Additional tunnels are also planned to protect the Potomac River and Rock Creek, and are scheduled to be completed by 2030. The Anacostia River was the highest priority because it was hit with far more sewer overflows than other waterways, according to DCist.
The new tunnel passes beneath DC’s dense urban corridor, which includes several landmarks: part of RFK Stadium, Langston Golf Course, the National Arboretum, Mount Olivet Cemetery and an Amtrak Rail Yard. A massive Herrenknecht EPB-TBM machine excavated and built the tunnel about 100 feet below the city, very close to these sensitive structures and utilities.
The project is funded primarily through monthly fees charged to DC Water customers.
