Southeast Collector Sewer

Driving through Ontario’s subsurface with four TBMs

The Southeast Collector plays a vital role in transporting untreated sewage for treatment. The 15-kilometre-long trunk sewer transports effluence to the Durham Region wastewater treatment plant while also serving as a backup for the existing sewer system.

The tunnel was excavated at depths ranging from 5 to 50 metres using four Earth Pressure Balance Tunnel Boring Machines (EPB TBMs) with precast concrete lining segments. The system was further complemented by 16 shafts constructed using secant pile walls, ground freezing, slurry walls and shotcrete. A final cast-in-place concrete lining completed the structure.

Beyond the tunnel works, the project included a range of supporting facilities. These comprised corrosion and odour control systems, flow diversion and metering, as well as maintenance and interconnection chambers. In addition, 15 construction compounds were developed, roads were widened and traffic signal installations were completed at selected intersections.

The SEC Trunk Sewer enhances regional wastewater reliability, supports environmental protection and increases operational flexibility for both York and Durham Regions. 

Scope of Work

• Construction of the 15 km trunk sewer 
• Tunnel excavation using four EPB TBMs 
• 16 shafts 
• Installation of cast-in-place concrete lining 
• Odour, corrosion and flow control systems 
• Maintenance and connection shafts 
• Road widening and improvements