Blue Plains CSO shortlist - TunnelTalk
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Washington DC Blue Plains RFPs Jul 2010
Shani Wallis, TunnelTalk
Three short-listed groups are invited to present design-build proposals for the first of four major tunnel contracts to control combined sewer overflows into the Potomac and Anacostia Rivers in the Washington DC area. The estimated $300 million Blue Plains Tunnel comprises 23,600ft x 23ft minimum i.d. (7.2km x 7m) soft ground TBM tunnelling and four deep shafts of up to 25ft diameter and 150ft deep (7.6m x 46m).
p1

Fig 1. Blue Plains Tunnel alignment

The three groups and their lead design engineers selected from six groups that submitted statements for qualification earlier this year are:
Kiewit-Clark with Parsons Brinckerhoff
Kenny-Shea-Obayashi with Arup
Traylor-Skanska-JayDee with Halcrow
Impregilo of Italy and Dragados of Spain represented international interest in the work.
Two part technical and cost estimate proposals are due back on December 2nd with an award scheduled for early April and a notice to proceed for early May 2011.
Concurrently, an RFP for Construction Management services for the Blue Plains Tunnel was released this week on July 4th and are to be returned by August 19th. An industry outreach meeting to discuss the contract will be held on Monday 12th July at 1.30pm in Washington DC at the offices of project owner, DC Water (formerly DC WASA, District of Columbia Water and Sewer Authority). Telephone +1 202 787 2363 for more details. The Construction Management contract is scheduled to be awarded in February 2011 about month before the design-build construction contract is confirmed.
The Blue Plains Tunnel is the largest contract in the $2.2 billion Long Term CSO Control Plan (LTCP) by DC Water to build more than 12.8 miles (20.7km) of deep level tunnels with 16 shafts, and several pumping stations and river crossings, to reduce combined sewer overflows by 96% overall and by 98% in the Anacostia River alone. Jacobs Associates (known as JA Underground for the contract) is the tunneling and geotechnical engineers LTCP Program Consultant Organization with Greeley & Hansen managing hydrology and scheduling.
p1

Fig 2. Elements of the full LTCP

According to site investigations, the geology on the alignment of all four LTCP tunnels is mostly clayey and silty soils with sandy interbeds. "Closed face TBM tunneling is required in these conditions and the documents for the Blue Plains Tunnel leave the choice of slurry or EBP tunneling to the design-build teams," explained Bill Edgerton of JA Underground. "There is a GBR with the contract documents and an addendum is to be released to include results of geotechnical cores being drilled from barges into the bed of the Anacostia at the moment as the first opportunity to gain access for that work in the river."
One machine is envisaged as there are strict limitations on working in this dense urban environment and tunneling can only advance from the shaft at the Blue Plains treatment plant. A new or a rebuilt machine is permitted and bolts or dowels on the longitudinal joints of the gasketed segmental lining are allowed.
"Sinking the shafts is a challenging part of the job," said Edgerton. "Slurry walls or ground freezing options are available to the design-build teams."
Construction of the $2.2 billion LTCP is driven by a court ordered consent decree to reduce CSOs into the rivers by March 23, 2018 for the first two of the four program contracts and by March 23, 2025 for the last two. The second of the River Area Tunnels with the Blue Plains Tunnel, is the Anacostia River Tunnel (ART) which comprises 12,500ft of 23ft i.d. (3.8km x 7m) tunneling starting at the Poplar Point shaft and passing under the river to terminate just south of the RFK Stadium. Design of the ART has started and the contract is scheduled to be advertised about a year after the start of the Blue Plains Tunnel towards a construction state date of November 2013.
The last two contracts in the program, the total 16,600ft (5km) Northeast Boundary Branch Tunnels (NEBBT) and the 15,170ft (4.6km) Northeast Boundary Tunnel (NEBT) have construction start dates in 2018 and 2021.
Financing and funding of the project is in DC Water's current financial plan and the Authority is on track to meeting the court ordered construction timeline.
References
Clean up Washington DC waterways - TunnelTalk, Aug 2009

           

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