The District of Columbia Water and Sewer Authority (DC Water) named its massive tunnel boring machine (TBM), christened it with D.C. tap water, and prepared to send it underground to tunnel more than four miles along the Potomac at a depth of approximately 100 ft.
The machine is more than 400 ft long and weighs more than 1,323 tons. It will dig the Blue Plains Tunnel, which is a portion of DC Water's Clean River Project to significantly reduce combined sewer overflows (CSOs) and improve water quality in the District of Columbia.
District of Columbia Mayor Vincent Gray, U.S. Environmental Protection Agency Regional Administrator Shawn Garvin, D.C. Councilmember Mary Cheh, DC Water Board of Directors Chairman Allen Lew and DC Water General Manager George S. Hawkins participated in the event at the Blue Plains Advanced Wastewater Treatment Plant.
"Much like her namesake, 'Lady Bird' will be performing important work for the long-term health of our rivers," said Hawkins. "This tunnel system will reduce combined sewer overflows into the Anacostia by 98%."
As in many older cities, about one-third of the District has a combined sewer system. A CSO occurs during heavy rain when the mixture of sewage and storm water cannot fit in the sewer pipes and overflows to the nearest water body. CSOs contain bacteria and trash that can be harmful to the environment.
DC Water's plan to significantly reduce CSOs to the Anacostia River is to build massive underground tunnels that will store the combined sewage and runoff during intense rainstorms and then release it when the system has the capacity to treat it. Similar tunnels exist in cities like Chicago, Indianapolis and Atlanta.
"Earlier this year, I unveiled the Sustainable D.C. Plan, a 20-year plan to make the District the healthiest, greenest, most livable city in the nation," Mayor Gray said. "The Clean Rivers Project goes a long way to providing sustainability for the region, making our waterways healthier and cleaner."
DC Water's TBM was named "Lady Bird" after Claudia Alta "Lady Bird" Johnson, First Lady and wife of President Lyndon B. Johnson. She formed The Committee for a More Beautiful Capital, and encouraged her husband to declare the Potomac River "a national disgrace," which drew attention to the declining health of America's waterways and was a catalyst for the eventual Clean Water Act of 1972.
Starting from two deep shafts at Blue Plains, the Lady Bird TBM will tunnel 24,200 linear ft up the Potomac River and to the Anacostia River. Additional tunnels are also planned to reduce CSOs in the Potomac and Rock Creek sewersheds, although DC Water is also developing a green infrastructure pilot program.
Source: DC Water