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DC Water starts on major CSO program Oct 2011
Paula Wallis, TunnelTalk
A soggy day seemed appropriate weather to celebrate the start of construction of an ambitious CSO program in Washington DC. On Wednesday October 12, 2011 Mayor Vincent Gray along with representatives of DC Water and the construction team officially broke ground on the Blue Plains Tunnel, the first phase of the $2.6 billion program to nearly eliminate CSOs into the Anacostia and Potomac rivers and Rock Creek.

Ground breaking of the Blue Plains Tunnel

"There can be no overestimating the scale of this project - it's absolutely huge," said DC Water General Manager George S. Hawkins.
The $330.5 million tunnel contract includes 23,600ft x 23ft minimum i.d. (7.2km x 7m) of soft ground TBM tunneling and five deep shafts of up to 132ft (40m) diameter and 180ft (55m) deep.
The Traylor/Skanska/Jay Dee JV with design engineer Halcrow secured the design-build contract in March 2011.

Fig.1 Elements of the $2.5 billion Long Term CSO Control Plan

EPC, a specialty tunnel management firm holds the construction management contract on the tunnel project. The design-build delivery method was chosen mainly as a time-saving option to meet a court consent decree to reduce CSOs in the rivers by March 23, 2018.
After speaking with four TBM manufacturers the contract or selected a 7m diameter Herrenknecht EPB for the drive. The Blue Plains Tunnel contact includes a challenging slurry wall sinking of the large 132ft (40m) diameter shaft at the Blue Plains Treatment Plant. The 180ft (55m) deep shaft is in soft ground right next to the Potomac River.
The Blue Plains Tunnel is the first and largest of four major contracts to control combined sewer overflows into the Potomac and Anacostia Rivers. Running more then 100ft below the surface, this first tunnel will extend from the Blue Plains Treatment Plant in Southwest DC, roughly along the east bank of the Potomac, crossing under the Anacostia to terminate at a reception shaft at DC Water's main pumping station (Fig 1). The Blue Plains Tunnel along with the Anacostia River Tunnel that extends to near the RFK Stadium, together with their surface hydraulic facilities and a tunnel dewatering pump station, are scheduled to be put into operation by March 2018, providing relief to the Anacostia River first. The remainder of the tunnel north of RFK Stadium, called the North East Boundary Tunnel, is required to be completed by 2025.

DC Water General Manager George Hawkins opens the ceremony

Jacobs Associates is acting as the General Consultant for Tunnels and Geotechnical Engineering on the $2.6 billion program, while Greeley and Hansen is serving as the Program Management consultant.
The Clean Rivers Project is the result of a 2005 federal consent decree. DC Water is beginning discussions with the parties on reopening the agreement. The goal would be to explore green development technologies that could reduce or eliminate future pieces of the project, create jobs, green the District and reduce rate increases for customers. Other cities, notably Philadelphia, have proposed CSO solutions that rely heavily on green techniques instead of tunnels.
"We are looking at other ways to manage combined sewage in the Rock Creek and Potomac River sections," Hawkins said. "No city or utility has ever done a sustained and large-scale pilot study of green roofs, trees and porous pavement to help in those areas. We hope to do just that."
Meantime work begins on the Blue Plains Tunnel with the difficult shaft sinking at the Blue Plains Treatment Plant. Tunnel excavation is expected to begin in 2013.
References
Blue Plains Tunnel teams selected in DC - TunnelTalk, Mar 2011

           

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