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Washington DC loves Lucy

Residents of Washington DC have been declaring “I love Lucy” after the tunnel boring machine (TBM) working on a flood alleviation scheme in the city was christened with the name.

Named after Howard University’s first dean of women Lucy Diggs Slowe, the TBM will drive the First Street Tunnel (FST) part of DC Water’s Clean Rivers Project.

Lucy was officially named last weekend and is now being readied for launch by contracting joint venture Skanska-Jay Dee.

The TBM will initially launch without trailing gantries for the first 100m of the tunnel drive. In this configuration, the gantry sections will be located at the surface near the shaft and will feed the TBM with necessary fluids and power through umbilical lines that will be hung down the shaft and along the side of the mined portion of the tunnel. The excavated soils will be delivered to the shaft in muck box which will be lifted out with a crane. After this initial setup, the first five gantry sections will be added in-line and tunnelling will resume for an additional 100m. The remaining gantry sections will then be installed, the Channing Street Mining Shaft will be fitted with a rail switch, and the full-scale tunnelling operation will begin.

DC Water has said that at full production, Lucy is capable of tunnelling up to 35m per day but is expected to average 15m to 18m per day.

Clean aims

The Clean Rivers Project will reduce combined sewer overflows (CSOs) to the district’s waterways – the Anacostia River, the Potomac River and Rock Creek.

• It will cost approximately $2.6bn and is scheduled for completion in 2025, though portions of the Anacostia River will be relieved by 2018.

• The Clean Rivers Project will reduce CSOs to the Anacostia River by 98% and to all three water bodies by 96% overall.

• DC Water is starting the project with the most impaired water body, the Anacostia River, a slow-moving and shallow water body. The 21km tunnel system for the Anacostia is broken into three segments.

• The tunnel system ends at Blue Plains Advanced Wastewater Treatment Plant where the combined sewage will be treated before being discharged back to the Potomac River.

• The First Street Tunnel portion of the Clean Rivers Project will protect public health and safety by reducing recurring flooding in the Bloomingdale and LeDroit Park neighbourhoods.

• The accelerated design and construction schedule will provide substantial flood relief by March 2016 by providing storage for 35M litres of stormwater and wastewater. In 2022, the First Street Tunnel will connect with DC Water’s Northeast Boundary Tunnel.

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