$583M stormwater tunnel complete in DC

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. It connects with a segment that was finished 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’s designed to prevent river pollution during periods of intense rain and will also reduce flooding in northeast parts of the city, including in Brentwood where an Aug. 14 flood killed 10 dogs at a pet care business.
  • A joint venture of Italian firm Salini Impregilo and Cheshire, Connecticut-headquartered Lane Construction built the 27,000-foot-long, 23-foot diameter structure under a design-build contract, with design and engineering work from Denver-based Brierley Associates.

Dive Insight:

The tunnel is part of the Clean Rivers Project, which stems from a lawsuit that environmental groups filed in 2000 against the District of Columbia Water and Sewer Authority for allowing billions of gallons of untreated sewage to flow into area rivers. Construction on the overall tunnel system, which runs about 12 miles, began in 2011. The new segment broke ground in 2018.

The addition of this latest tunnel is designed to prevent 98% of sewer spills, and is a major step toward restoration of the Anacostia River. Additional tunnels are also set to be built to protect the Potomac River and Rock Creek, and are scheduled to be complete by 2030. The Anacostia River was the top priority because it was hit with far more sewer overflows than the other waterways, according to DCist.

The new tunnel passes under D.C.’s dense urban corridor, including 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 boring machine excavated and constructed the tunnel about 100 feet beneath the city, in close proximity to these sensitive structures and utilities

The project is mostly funded by monthly fees charged to DC Water customers.

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