Vancouver's twin tunnels reach target
Oct 2010
Shani Wallis, TunnelTalk
- Despite warnings of dangerous conditions ahead, the twin Seymour-Capilano water transfer tunnels in Vancouver, Canada are approaching their end point.
- The first of the two Robbins HP gripper TBMs on the twin tunnel contract completed its 7.1km long raw water tunnel on Thursday 14 October and the second machine, about 200m behind in the treated water tunnel, is expected to hit its end point in mid-November.
- The two 3.8m diameter rock TBMs have arrived at the location of the shafts at the Capilano end which will be excavated once the TBMs have been dismantled and the components withdrawn back through the tunnels they have completed. The raw water tunnel machine carried on about 30m beyond the shaft location points to make space for blasting of a dismantling chamber which will also be used for attaching the reamer to the pilot string to complete the shafts of about 270m deep as 3.5m diameter raise bores.
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7.1km Seymour-Capilano connection
- Rock conditions for the second part of the twin tunnels have generally been better than anticipated according to Bill Morrell, spokesperson for the project owner Metro Vancouver. "Higher groundwater inflows were encountered within the last hundred meters of the drives," explained Morrell. "and this was managed readily with a program of grouting."
- "Completion of the drives is a substantive milestone for the project," he said.
- The TBMs have been operated for the second part of their drives by Seymour-Cap Partnership, a JV lead by Frontier-Kemper and including JF Shea and Aecon that negotiated a contract to take over from where the previous contract with Bilfinger Berger was terminated in May 2008. Bilfinger Berger stopped work in January 2008 claiming that unstable rock conditions and dangerous rock bursts in the deep unlined rock tunnels were creating an unsafe working environment for the workers. When the contractor refused to resume work "in accordance with the contract" Metro Vancouver terminated its right to perform further work in May 2008 and negotiated the fixed price recovery contract in April 2009.
- Initially budgeted at $200 million, the overall cost of the tunneling component within a larger water treatment project by Metro Vancouver, is projected to double to $400 million. The original budget included the $105 million contract with Bilfinger-Berger while the projected increase includes the fixed price $180 million recovery contract with Seymour-Cap Partnership. The twin tunnels will convey water from a Capilano reservoir to the project's new plant for treatment at Seymour and return treated water to Capilano for distribution. The tunnels are designed to remain largely unlined with concrete and steel lining installed as per the original design and as required by the engineer, and pipe work in the shafts will connect to the treatment plant at the Seymour end and the reservoir and distribution network at the Capilano end.
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One of the twin Robbins HP TBMs
- All the same equipment mobilized by Bilfinger Berger when it started the job back in January 2005 was used by the Seymour-Cap Partnership for the completion contract. Following minor modifications of support installation equipment on the machines, including extension of the finger shield, TBM tunneling restarted in July and August 2009 respectively. As well as all the same equipment, work continued according to the original engineering design and support protocol completed by the owner's designer Hatch Mott MacDonald.
- According to information sent to TunnelTalk by a credible source, "conditions were much better then those portrayed at the change of contractor. After pushing through the so-called bad section and installing 33 ring sets, the rock became very stable. From that point on, and using appropriate support measures, [very few] additional ring sets were required in the drives. The last 40m were the hardest, after hitting 200psi of water on the last probe hole. The next week and a half was spent injecting grout before starting up again and reaching the end of the first TBM drive at 9.33pm on the evening of Thursday Oct 14th. With all said and done, it was a great project to be a part of and a thrill to finish was the comment."
- In an earlier article, Morrell said that progress during the final half of the drives was averaging about 15m a day. He predicted that the tunnel drives would be finished by fall 2010 and that the raise bores will take about nine months to complete. "Installation of steel lining and pipework in the shafts and at the ends of the tunnels will begin in 2011 and progress into 2012," he said, "with water flowing through the tunnels by early 2013,". In the meantime, the new filtration plant has been operating independently of the tunnels since fall 2009.
- Ironically, successful end of the twin TBM drives comes just as mediation talks get underway to resolve the differences between Bilfinger Berger and Metro Vancouver. Metro Vancouver filed suit to recover from Bilfinger-Berger the additional costs of completing the tunnels. Bilfinger Berger filed a suit against Metro Vancouver in attempts to recover funds lost as a result of the termination of contract and recovery ownership of equipment confiscated for completion of the tunnel, including one of the new TBMs. Mediation is an attempt to avoid inevitably lengthy and costly court case trials.
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Vancouver's twin tunnels about 75% complete - TunnelTalk, May 2010
Twin tunnel restart comes at a high price - TunnelTalk, April 2009
Vancouver's twin tunnels contract terminated - TunnelTalk, May 2008
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