Giant sinkhole swallows van, causes chaos in downtown Ottawa
Matthew Pearson, Ottawa Citizen
Published on: June 8, 2016 | Last Updated: June 8, 2016 6:57 PM EDT
An enormous sinkhole swallowed three lanes of Rideau Street Wednesday morning, consumed a parked van, forced the evacuation of the Rideau Centre and nearby hotels and businesses, and left Ottawa’s downtown core in a state of chaos that could continue for days to come.
City officials were reluctant to link the sinkhole to light rail tunnel construction happening two-dozen metres below, but whatever the cause, the effect is the indefinite shuttering of a key downtown intersection and the rerouting of dozens of OC Transpo and Gatineau STO buses that pick up thousands of commuters on Rideau Street every day.
The Rideau sinkhole is just east of the intersection with Colonel By Drive, but has shut down a number of downtown streets in the vicinity.
Wellington and Rideau was closed between southbound Elgin and Dalhousie, while Colonel By and Sussex Drive are closed between Daly Avenue and George Street. Northbound Elgin is also closed between Albert and Rideau.
And the Mackenzie Bridge between Waller and Elgin streets is closed to general traffic for the afternoon rush hour on Wednesday to accommodate extra buses rerouted off Rideau Street.
Residents are asked to avoid the area and transit riders told to prepare for delays.
“We just don’t know how long it’s going to take, it’s a significant sinkhole in the downtown core. It has a major impact on our largest retail shopping centre, one of our major hotels, as well as one of the busiest intersections and bus routes for both STO and OC Transpo,” Mayor Jim Watson said during an afternoon media briefing at Ottawa City Hall.
“Be prepared for delays because this could take some time.”
The mayor and Rideau-Vanier Coun. Mathieu Fleury were to tour the site later in the day.
Pictures of the sunken-in roadway began circulating on social media at around 10:30 a.m., followed by reports to the city of a water main break and gas leak. A power outage in the area was also reported.
The Rideau Centre and surrounding buildings were evacuated immediately and remained closed to employees and the public for much of the day. The primary reason for those evacuations was a gas leak, that blanketed the downtown in a foul smell. The leak was soon repaired. The mall is expected to reopen Thursday morning.
Meanwhile, officials at city hall — who learned about the sinkhole during an otherwise uneventful city council meeting — scrambled to convene an emergency management meeting.
“All hands are on deck to make sure the site is secured and no harm is done to any individual,” the mayor told reporters after Wednesday morning’s council meeting ended.
No injuries were reported and everyone working in the LRT tunnel was accounted for, Watson said during the afternoon media briefing.
He added the city was putting all of its resources “towards determining the cause of the situation and to conduct the necessary repairs as quickly as possible.”
Many speculated about what role, if any, LRT tunnel construction may have played, but Watson said that wouldn’t be known for at least several days.
“We can’t confirm whether the tunnel had any impact on the sinkhole or whether it was a water main break or whether it was a leak of some type that destabilized the soil,” Watson said, noting the LRT tunnel is substantially below where the water main break occurred.
The tunnel was not affected by the sinkhole, though work was halted right away. There were no reports of water or debris falling into the tunnel.
Crews have finished digging out the future Rideau station cavern and were working on the final 50 metres of tunnel between Colonel By Drive and the Rideau Canal, said Steve Cripps, director of the city’s rail implementation office.
Digging in that area’s soft ground calls for a different tunnel design, different temporary support structures and even the hiring of a special adviser.
In rock, crews use a 135-tonne roadheader, a 20-metre long machine with a spiked fist at the front that punches away at the rock. But in clay and sand, they must use a smaller excavator, which takes smaller bites than the roadheader, and use more reinforcements.
Long before the city even put the LRT project up for tender, it knew about the soft ground beneath Rideau and paid for geotechnical work to understand the challenges posed by the formation known as the Rideau Valley.
Cripps says it’s too early to know if the soil conditions were a factor.
“We don’t really know if these soil conditions have caused this, it’s too early to speculate on the relationship between those soil conditions and the water main and what happened,” he said.
After the initial collapse, a second collapse, caught on camera by some eyewitnesses, swallowed a minivan.
There was no one in the van, which the city says belonged to a private citizen who was parked there and tried unsuccessfully to convince firefighters to let him move it before it was swallowed by the sinkhole.
With Ottawa set to host the North American leaders summit in a few weeks, the intersection of Rideau and Sussex could conceivably be part of the motorcade route.
Ottawa police Chief Charles Bordeleau said it’s “too early to tell” if that will have to change. “If we have to make adjustments to any motorcade routes, we will do so,” Bordeleau said.
Although this latest closure of Rideau Street may be a pain to many transit users, most drivers should already be accustomed to avoiding the area.
Rideau between Sussex and Dalhousie was closed to most vehicle traffic last August as part of LRT construction, while one lane in each direction was restricted to OC Transpo and STO buses, taxis, delivery vehicles and LRT construction vehicles.
http://ottawacitizen.com/news/local-news...r-outage-forces-rideau-centre-evacuation
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