Strabag to build Toronto wastewater tunnelSep 2011
Paula Wallis, TunnelTalk
Building on from its mega Niagara Falls hydro tunnel project, Strabag has landed another major tunneling contract in Canada, this time in Toronto. The company has secured the CAN$290 million (about €200 million) contract to build the 15km (9.3 mile) long wastewater tunnel for The Regional Municipality of York. Strabag outbid three other pre-qualified contractors that submitted proposals by the May 6th 2011 deadline (Table 1). All of the bids were well below the approved CAN$546.1 million budget for the sewer project.
Fig 1. Trunk sewer alignment
The Southeast Collector contract includes the tunnel, 16 shafts and various bio-filters to clean the air and remove odors, as well as the upgrade of a nearby 3km stretch of road.
Four 3.6m (11.8ft) diameter Caterpillar EPBMs will excavate the tunnel concurrently. A machine will be launched from each of Shafts 1 and 6, with the remaining two launching in opposite directions from Shaft 10 (Fig 1). The TBMs will be dressed with 305mm (12in) disc cutters.
When all four TBMs are in the ground they are expected to complete as much as 60m (197ft) a day. Ground conditions expected along the alignment at between 10m to 40m (33-131ft) deep, consist of glacial tills, both plastic and non-plastic, sands, silts, gravels and clays. Cobbles and boulders of various sizes are also anticipated.
To optimize the construction schedule and avoid long procurement timelines and cost premiums, the Owner retained control over some project activities that are typically subcontracted by the contractor. It completed advanced procurement of the four TBMs and of the the precast concrete segmental liners; upgraded haulage roads to be used by the contractor; conducted the archeological investigations and pre-clearance of the shaft sites; relocated utilities; and installed power to all of the construction sites. Much of the advanced procurement and infrastructure improvements were completed prior to tendering the main contract. The Owner placed the order for the TBMs with Caterpillar (then Lovat) in September 2009. According to the Owner the cost of the advance works total about CAN$70 million to date.
Table 1. Southeast Collector construction bids
Dragados/Technicore Underground JV
Jay Dee/Michels JV
Additional measures taken by the Owner to limit risk and cost include:
• Owner-controlled insurance program
• A Disputes Resolution Board
• Advanced identification of available muck disposal sites
• Maintenance and funding of spare parts for TBMs by the Owner
• Direct Owner responsibility for commission of the odor control equipment and associated facilities.
It is not the first time Toronto has taken unusual steps to manage risk. The Toronto Transit Commission pre-purchased four Caterpillar EPBMs and the precast concrete liner for the 8.6km (5.4 mile) Toronto-York Spadina Subway Extension. The TBMs on the CAN$279 million tunneling contract began their drives in June of this year (2011).
The new contract for Strabag follows its breakthrough on the 10km (6.2 mile) hydroelectric tunnel at Niagara early this year using the world's largest hard rock TBM. In a prepared statement Strabag CEO Hans Peter Haselsteiner said he was pleased for company workers, who have settled into new lives in Canada, and can now remain. "They have done a good job and the administration of York Region is convinced of the quality of their work in Canada."
AECOM/Hatch Mott MacDonald JV designed the tunnel and holds the construction management services for a total contract value of CAN$71.3 million.
TBMs at Caterpillar's manufacturing facility in Toronto
The new trunk sewer will carry untreated sewage from York Region to a treatment plant in Durham Region in the southern part of the City of Pickering. As the capacity of this system is reaching its limits, expanding and building a new sewer collector is necessary to service planned and approved growth for both regions. The tunnel will also serve as a critical backup for the exiting sewer line.
The new sewer line is anticipated to be in service by March 2015.
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