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Second breakthrough for DC CSO mega-project 6 Jan 2016
DC Water News Release
DC Water records its second major TBM breakthrough as part of the US$2.6 billion effort to reduce CSO overflows and flooding in Washington DC.
Excavation of First Street Tunnel completed

Excavation of First Street Tunnel completed

The refurbished Herrenknecht EPBM, owned by the Skanska/Jay Dee contractor joint venture that was awarded the accelerated contract in October 2013, broke through into the reception shaft at the end of its seven month long, 823m drive, on December 22 (2015).
TBM Lucy mined under First Street, NW, from Channing Street to Rhode Island Avenue, to complete the drive. The contract was broken out early from the 7,925m long Northeast Boundary Tunnel that it will ultimately connect with. These tunnels, along with the completed 7,200m Blue Plains Tunnel and the under construction 3,800m Anacostia Tunnel will create a continuous 20km connection with the Blue Plain Wastewater Treatment facility by 2022.
“We are pleased to reach this important milestone in the project and are grateful for the continued patience of the impacted community,” said DC Water CEO and General Manager George Hawkins. “We will continue to work with the neighborhood to complete this essential project as soon as possible to provide flood relief for residents.”
When it is commissioned later this year the First Street Tunnel will store and then pump combined sewage up into the existing sewer system during and after rainstorms to keep it off of streets and out of basements. It is designed to mitigate flooding from undersized sewers in the Bloomingdale and LeDroit Park neighborhoods.
Scott Hoffman, Skanska/Jay Dee Project Manager for the First Street Tunnel, said: “We’re proud of the end result, and the positive impact it will have on the community: it’s a great accomplishment.”
TBM Lucy is the second machine to complete her drive this year. In July, TBM Lady Bird completed a two-year, 7,200m drive to complete excavation of the Blue Plains Tunnel.
TBM Lucy will now be dismantled and 99% recycled. Work now continues to connect the existing sewers along First Street, NW, to the new tunnel.
References
DC Clean Rivers First Street Tunnel tour - TunnelCast, October 2015
DC calls qualifiers for city’s longest tunnel - TunnelTalk, September 2015
DC prepares for Anacostia EPBM launch - TunnelTalk, January 2015
Washington DC accelerates flood relief award 30 Oct 2013
Peter Kenyon, TunnelTalk
The Skanska/JayDee JV is awarded a US$157 million design-build contract to construct the First Street Tunnel (FST) as part of DC Water's US$2.6 billion Clean Rivers Project to reduce combined sewer overflows and bring long-term flood relief to the US capital.
First Street EPBM arrival imminent 21 Jan 2015
Refurbished  EPBM for First Street Tunnel

Refurbished EPBM for First Street Tunnel

The refurbished contractor-owned TBM that will excavate the 823m long First Street tunnel as part of DC Water’s US$2.6 billion Clean Rivers Project is expected on site later this month.
“The EPBM, previously used on a project in Abu Dhabi in 2012, has been recently refurbished in Kehl, Germany, by its original manufacturer, Herrenknecht,” Pamela Mooring of DC Water told TunnelTalk. “The 22.8 ft (7m) diameter EPBM has been packed and shipped with a scheduled arrival on the job site in Washington, DC, expected in late January 2015. It will be assembled on site and in use through 2015.”
The 2,700ft (823m) tunnel is broken out of the more substantial North East Boundary Tunnel (NEBT) contract which is not yet at procurement stage and is not due to be completed until 2022. It begins at the McMillan Sand Filtration Site and runs below First Street NW to Rhode Island Avenue NW (Fig 1).
Design-builder Skanska/JayDee JV will be responsible for design of the precast concrete segmental tunnel lining. The DC Clean Rivers Project's Consultants Organization is managed by the team of Greeley & Hanson and Jacobs Associates who prepared the RFP contract documents on behalf of DC Water. Skanska is the majority construction partner with a 60% share of the contract.
Pamela Mooring of DC Water told TunnelTalk from Washington DC: "The First Street Tunnel was in DC Water's CSO Long Term Control Plan as a branch of the NEBT. At the recommendation of the Mayor's Task Force on Flood Prevention, the FST was broken out as a separate construction contract on an accelerated schedule to provide a medium-term level of flood protection by March 2016 until FST connects to the NEBT in 2022 when a DC standard 15-year storm level of flood protection will be achieved."
In addition to the 23.8ft (7m) o.d. main tunnel, which will be excavated using a refurbished contractor-owned TBM, project scope includes a number of shafts and a temporary underground pump station that will be decommissioned and removed once the tunnel is connected to the NEBT and a gravity system becomes operational. The main underground components are:
823m First Street Tunnel

823m First Street Tunnel

• A 65ft (19.8m) i.d. launch shaft at the McMillan Sand Filtration site
• A 20ft (6.1m) i.d diversion chamber and drop shaft to a depth of 95ft (29m) which connects to FST via an adit approximately 375ft along the south edge of Adams Street
• Three diversion chambers at Fifth and First Streets with a 23ft i.d. drop shaft approximately 90ft (27.4m) deep that is connected to the FST by a 75ft (22.8m) adit.
• A temporary below grade pump station and pump shaft in the parking lot on the south west corner. The shaft has an inside diameter of 22.5ft (6.85m) and is approximately 85ft (26m) deep. It is connected to the FST by a 60ft (18.3m) adit. This location also has a force main, a metering vault and a discharge manhole structure that allows the tunnel to be dewatered back into the existing wastewater system for treatment at the Blue Plains Advanced Wastewater Treatment Plant after storms subside and system capacity is restored.
Clean Rivers Project tunnels

Clean Rivers Project tunnels

Tunnel construction is expected to start in early 2015, with substantial completion expected the following year. When completed it will store up to 8 million gallons of stormwater, capturing it before it can make its way to the combined sewer system and then pumping it back into that sewer system once the storms subside. Advancing construction of the FST will alleviate some of the sewer backups and overland flooding experienced in low-lying neighborhoods, but protection against severe storm events will not be achieved until a gravity-fed connection is made with the NEBT.
The FST is scheduled to connect with the NEBT in 2022, one of three large-scale CSO storage tunnels that are being constructed. The first, the US$330.5 million 7.2km x 7m i.d. Blue Plains Tunnel, is already under construction by the Traylor/Skanska/JayDee JV. The TBM, launched in July of this year, is reported this week to have completed 1,120ft (341m), and is currently on a scheduled 4-6 week stop while the mucking conveyor is installed.
Later this year a JV of Impregilo/SA Healy will launch on US$253.9 million TBM construction of the 3,810m x 7m i.d. Anacostia River Tunnel, which will connect with the Blue Plains Tunnel (and eventually the NEBT) and carry water to the new Blue Plains Advanced Wastewater Treatment Plant.
Procurement for the 4,624m NEBT and a network of branch tunnels has not yet begun.
References
Underground solution saves US$500 million - TunnelTalk, July 2013
DC advancing clean river mega-project - TunnelTalk, May 2013
Blue Plains tunnel teams selected in DC - TunnelTalk, March 2011
DC Water starts on major CSO program - TunnelTalk, October 2011
Miles of new tunnels to clean up Washington DC waterways - TunnelTalk, August 2009

           

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