Another DC Water tunnel boring machine (TBM) has completed her mission, creating a nearly two-and-a-half-mile-long tunnel that will be used to help improve the water quality in the Anacostia River. The TBM, named Nannie, completed the excavation of the Anacostia River Tunnel (ART) on Saturday, exactly one year and a day after she began mining on November 4, 2015.

Nannie‘s journey started in a deep shaft near RFK stadium and ended when she broke through the wall of another shaft at Poplar Point, near the intersection of DC 295 and the Suitland Parkway. The tunnel is 23 feet in diameter and runs approximately 100 feet below the surface, crossing under the Anacostia River, CSX railroad tracks and Metro’s Green Line. It connects to another tunnel completed in 2015 by a tunnel boring machine named Lady Bird.

The tunnels are part of DC Water’s Clean Rivers Project aimed at controlling combined sewer overflows to the waterways of our nation’s capital.  The project includes a system of tunnels, drop shafts and diversion structures designed to capture combined sewage, which is a mixture of storm water runoff and sanitary sewage, and deliver it to the Blue Plains Advanced Wastewater Treatment Plant.  The project also includes Green Infrastructure which uses vegetation and soil to manage stormwater where it falls.

“Our Clean Rivers Project team continues to push forward at an incredible pace, and the completion of this tunnel is another key milestone to celebrate,” said DC Water CEO and General Manager George S. Hawkins. “We applaud everyone who has played a part in keeping this work on schedule to meet our ultimate goal, which is cleaner water everyone can enjoy. That will be a great return on the investment our ratepayers are making in this massive project.”

DC Water is aggressively working toward a March 2018 deadline for placing in operation a major part of the tunnel system serving the Anacostia River from RFK Stadium south to the Blue Plains Advanced Wastewater Treatment Plant near the Wilson Bridge.  The Anacostia Tunnel was the last major tunnel to be excavated to meet the 2018 deadline.

Nannie was blessed by Cardinal Donald Wuerl, the Catholic archbishop of Washington, and visited by Vice President Joe Biden prior to starting work on the tunnel. She was named after Nannie Helen Burroughs who was an African-American educator and civil rights activist in the District.

The tunnel is being constructed by Salini-Impregilo / Healy / Parsons (IHP) joint venture. More than 38 million gallons of combined sewage can be stored in the tunnel during rain events and then slowly released to Blue Plains for treatment. You can view time lapse video of the tunnel at https://youtu.be/L0QHHRe8deU.

When the Clean Rivers Project is complete, DC Water will have reduced combined sewer overflow volume by 96% overall with a 98% reduction for the Anacostia River. For more information on the Clean Rivers Project, please visit: dcwater.com/cleanrivers