Two-hundred-sixty feet below the surface of Lake Ontario, crews worked day and night to expand Toronto’s wastewater treatment capacity. The Ashbridges Bay Treatment Plant Outfall project, part of the largest and most significant stormwater management program in the city’s history, sought to create a new fallout and watertight shaft to replace the existing 80-year-old system. The project required extensive underground tunneling with an 11,500-foot tunnel and 50 connected risers. The contract for the tunneling and concrete work was awarded to Southland Mole of Canada and Astaldi Canada Design and Construction Joint Venture. Southland Mole of Canada, an excavation company specializing in
