The main access shafts for the drives have been constructed and the starter and blind tunnels have been excavated. The first tunnel boring machine (TBM) was delivered to shaft one and started operating in July 2012.

The Southeast Collector Project consists of the construction of 15 km of gravity trunk sewer and six related facilities, which will be able to convey a maximum flow of approximately 14 cubic metres per second.

The sewer will have an inside diameter of 3 m and will be constructed using four 3.62 m diameter Caterpillar TBM, with earth pressure balance capability, which enables the TBM to operate below the water table without the need for dewatering. As the soil is excavated, pre-cast concrete segments will be assembled within the TBM forming a circular tunnel liner as the TBM moves forward.

The Regional Municipality of York states that the TBMs will start from ‘launch shafts’ at the following locations: Finch Avenue east of Valley Farm Road (Shaft 1), Altona Road south of the hydro corridor (Shaft 6), and two from York Durham Line and 14th Avenue (Shaft 10), travelling in opposite directions.

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To facilitate tunnel construction, construction shafts will be excavated vertically from the ground level down to the future location of the tunnel. These construction shafts provide access for equipment and materials.

The $US291 million contract for construction of the Southeast Collector Trunk Sewer was awarded to STRABAG Inc, best known in North America for its work, currently underway, on the 10.1 km Niagara Tunnel Project.

The project has been designed by a joint venture of Aecom and Hatch Mott MacDonald.

Construction of the sewer is expected to be completed in 2015.