Heavy rains and an aging sewer pipe are the likely cause of a giant sinkhole that opened up on Finch Avenue West, east of Dufferin Avenue, which will force drivers to use alternate routes for several days, possibly even several weeks, city of Toronto officials said Sunday afternoon.
Finch Avenue between Bathurst and Dufferin has been closed to drivers since late Friday night when one crater and then another opened up in the eastbound lanes.
One sinkhole is approximately five metres in diameter and 14 metres deep, but affects a much larger area underneath the roadway. A second sinkhole immediately east of the original sinkhole is about five meters in diameter and approximately three metres deep.
"We are unable to advise when it will reopen due to the investigation and engineering work [needed]to determine how structurally sound the roadway is underneath," Mayor David Miller told reporters at the scene.
Toronto Water general manager Lou Di Gironimo said the road could be closed for at least several days and, depending on the damage, possibly several weeks.
Finch Avenue West near Bathurst Street is closed to all but local traffic, while Eastbound Finch remains closed at Dufferin Street, according to the city.
City engineers are still trying to determine the risk of additional underground sinkholes before they can go down to inspect a 60-year-old, 18-inch corrugated metal storm water pipe, buried about 10-12 metres below the surface, that is believed to have collapsed.
The pipe drains in an easterly direction into the nearby G. Ross Lord Dam (linked to a branch of the West Don River) that serves as flood protection for the city.
Mr. Di Gironimo said the dam is about 2.5 metres higher than normal for this time of the year because of intense rainfall in recent days.
Several car drivers experienced a depression in the road Friday night and notified the city, which promptly sent out emergency crews and subsequently closed the road in both directions.
The Toronto Transit Commission will also adjust its bus schedule on Finch.
Mr. Miller and officials said there was no strike-related impact because the city hires private contractors for these kinds of road and sewer repairs.