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EPBs for San Francisco as station bid opens Mar 2012
Paula Wallis, TunnelTalk
Two Robbins EPBMs have been ordered for the running tunnels of San Francisco's Central Subway and the next contract, for the underground station at Chinatown, has been released for bid.
The San Francisco Municipal Transportation Authority (SFMTA) released contract documents for the Chinatown station on Tuesday (February 28) after issuing an initial Notice to Proceed (NTP 1) to the Barnard/ Impregilo/ Healy (BIH) Joint Venture on January 27 for the running tunnels.
Artist impression of the Chinatown Station

Artist impression of the Chinatown Station

The JV won the contract with a bid of $233.5 million in June 2011. With the NTP 1 in hand the contractor has ordered two Robbins EPBMs for the 1.7 mile (2.7km) drives, which mostly lie below the groundwater table and through poorly consolidated silty and sandy deposits of the Colma Formation.
The contract has three distinct NTP authorizations: NTP 1 ($35 million) authorizes procurement of the TBMs, NTP 2 ($36 million) authorizes construction of the tunnel launch box and contractor's work area and NTP 3 ($163 million) authorizes commencement of tunneling, which includes construction of approximately 8,240ft (2.51km) long precast concrete segmentally lined twin-bored guideway tunnels, construction of five emergency cross passages and construction of station end walls. TBM launch is expected around May of 2013.
Concerning the station bid process, a pre-bid conference is scheduled later this month (March 20), with bids due by May 8. The Chinatown station is one of four new stations on the $1.6 billion Central Subway project that is moving into construction.
Existing building to be demolished for new station

Existing building to be demolished for new station

The SFMTA released contract No. 1254 following acquisition of the property on the corner of Stockton and Washington Streets that will be the future home of the Central Subway's Chinatown Station.
According to the bid documents the scope of works for the estimated $233.5 million contract includes, but is not limited to:
• Structural and geotechnical instrumentation and monitoring of project structures and adjacent existing utilities, buildings, utilities and infrastructure.

• Demolition of 933-949 Stockton Street building.
• Performing all hazardous abatement work for 933-949 Stockton Street building.
• Excavation and support of the headhouse at the off-street parcel at the southwest corner of Washington and Stockton Streets by braced slurry wall methods.
• Excavation, support, and concreting of the mined Cross-Cut Cavern from the headhouse by the sequential excavation method (SEM).
• Excavation, support, and concreting of the mined Platform Cavern by SEM.
• Excavation and construction of mined emergency egress shaft and adits.
• Supply and installation of mechanical systems including (emergency ventilation), fan plant and HVAX work in the station.
• Supply and installation of electrical voltage and 120V systems.
• Supply and installation of communication and station systems.
Central Subway alignment

Central Subway alignment

• Installation of compensation grout pipes and subsequent compensation grouting for protection of adjacent buildings.
• Temporary sump dewatering stations.
• Ancillary surface work.
• Handover of temporary tunnel utilities and sump dewatering to follow on contracts for construction of the subway stations, trackway, traction power and control systems.
• Demobilization and site restoration.
On the funding front, President Obama's budget proposal for fiscal year 2013 recommends investing $150 million in the Central Subway. Funding would be part of the Federal Transit Administration's (FTA) New Starts Program. The project is also anticipating a $942 million full funding grant agreement from the FTA in May or June of this year.
When complete, the 1.7 mile (2.7km) Central Subway will extend light rail service to the Financial District and Chinatown, as well as provide direct connections to BART and Caltrain, which are the Bay Area's two largest regional commuter rail services. The Central Subway is scheduled to open to the public in 2018.
References
Central Subway tunnels contract awarded - TunnelTalk, June 2011
Tight race for Central Subway running tunnels - TunnelTalk, June 2011
Bidding signals start of San Francisco Subway - TunnelTalk, June 2011

           

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