Mount Pleasant Road has re-opened after an overnight closure that occurred when work crews digging a hydro tunnel hit an underground stream.
According to Toronto Fire Services district chief Paul Halls, crews had tunneled about 48 metres underground when they ran into trouble. About three-quarters of the way down, minor water leaks were detected. However, technicians were able to inject concrete into the tunnel walls to stop the leak.
They continued digging, but ran into a major leak further down, which they were unable to plug with concrete.
The Toronto Fire Service was then called to the scene to begin filling the tunnel with water -- a technique used to reduce pressure and prevent a collapse. Once the water rises to the level of the leak, pressure coming in from the leak subsides and the tunnel walls typically stabilize.
The vertical tunnel is intended to house above-ground hydro cabling which is being moved underground. The cables feed electricity to the city's downtown core.
Earlier, police had shut down Mount Pleasant Road between Inglewood and Roxborough Drives, just south of St. Clair Avenue, as crews worked to stabilize the tunnel. The road reopened at about 6:40 a.m.
