The TBM digging a third hydro tunnel under the city of Niagara Falls passed the 6km point on its 10.2km journey.
The TBM, named Big Becky, is operating 90m below Stanley Avenue just south of Highway 420. Big Becky averaged more than 11m progress per day in February.
About 20 workers are currently busy at the tunnel outlet assembling the equipment needed to install the arch lining. This equipment will be about 450m in length.
The tunnel lining will consist of a layer of sprayed concrete, installed at time of boring, a waterproofing membrane and a permanent 600mm thick concrete liner of unreinforced, cast-in-place concrete. Construction of the arch lining is due to begin this spring.
Crews are now beyond the 4km mark of the invert lining.
Work on the intake structure, located at the International Niagara Control Works (INCW), about 2km upstream from the Horseshoe Falls, was suspended for the winter but is due to resume this month. Later this year, well in advance of Big Becky’s arrival, workers will build the reinforced concrete intake structure within the cofferdam and rock cut on the upstream side of the INCW.
