TORONTO — The last piece of the micro-tunnelling boring machine (MTBM) trapped underneath Old Mill Drive in Toronto has been removed.
Crews mobilized around 7 a.m. yesterday (Oct. 11) and the tail of the micro-tunneling boring machine was removed around 8:15 a.m. by a crew of eight workers, a City of Toronto spokesperson reported.
“A pulley system was used to draw the machine out of the tunnel and into the shaft, then a crane was used to hoist the machine out of the shaft and onto a flatbed truck to relocate it from the work zone,” the spokesperson stated in an email to the Daily Commercial News. “The machine will be inspected to determine its condition and whether it can be restored or salvaged.”
In April 2022, the $3 million machine was being used to construct a new 900-millimetre-diameter stormsewer along Old Mill Drive as part of the Basement Flooding Protection Program when it became entangled in steel tiebacks underground that were leftover from the building of a condo development.
In 2022, the original cost estimate for the emergency work to retrieve the machine, which was based on the best estimate of the scope of work and costs at the time, was around $8.9 million. The extent of the emergency retrieval work became clearer this spring and staff determined the cost may increase up to an additional $16 million.
In July, the city said the cost to remove MTBM nearly tripled from $9 million to $25 million due to complications. Clearway Construction Incorporate was the contractor removing the machine.
With the machine now removed, the city will resume work on the new sewer. Staff expect that work on the Basement Flooding Protection Program project for Old Mill Drive will be complete by the end of this year, with roads reopening at that point. Some site restoration work will take place next spring.