MEC&F Expert Engineers : A giant sinkhole that rapidly filled with water next to a major shopping mall in downtown Ottawa caused a gas leak, collapsed a road and forced the evacuation of all nearby businesses.

Wednesday, June 8, 2016

A giant sinkhole that rapidly filled with water next to a major shopping mall in downtown Ottawa caused a gas leak, collapsed a road and forced the evacuation of all nearby businesses.


Massive sinkhole closes Rideau Street in downtown Ottawa
Rideau Centre mall, businesses evacuated and tourists asked to avoid area

CBC News Posted: Jun 08, 2016 10:47 AM ET Last Updated: Jun 08, 2016 5:08 PM ET




A sinkhole formed Wednesday morning near the Rideau Centre mall and a light rail construction site in downtown Ottawa. (CBC)


A giant sinkhole that rapidly filled with water next to a major shopping mall in downtown Ottawa caused a gas leak, collapsed a road and forced the evacuation of all nearby businesses.

The sinkhole appeared at about 10:30 a.m. ET Wednesday near the corner of Rideau Street and Sussex Drive, at a light rail construction site next to the Rideau Centre, about two blocks east of the Château Laurier hotel.

Soon after forming, the sinkhole spread across the entirety of Rideau Street, stretching from the south sidewalk to the north sidewalk. A van parked on Rideau on the north side of the sidewalk, as well as a light standard, fell into the hole as it grew.

A large volume of water could also be seen gushing inside the sinkhole due to a water main break, but the water was soon shut off.


Tom Herlihy was on Rideau Street near the Chateau Laurier when he heard and smelled natural gas.

"A high-pressure natural gas line escaping is very distinct, it's a high-pressure whistle. You could smell it in the area immediately, and people were running away from it, you could tell something was amiss," he said.


Tom Herlihy smelled natural gas before he saw the sinkhole. 'People were running away from it, you could tell something was amiss,' he said. (CBC)

Herlihy went to an upper floor of the Chateau Laurier to get a better look.

"I caught the hole expanding and the car falling in and the gas just roiling the water, causing the dirt underneath the street to erode and collapse. And it's really deep," he said.

Elaine Tamblyn-Watts was in a Victoria's Secret change room at the Rideau Centre when a siren rang and a voice told people in the mall to leave the building. She said the scale of the sinkhole surprised her.

"I can't believe the size of it, it's just a clear drop, the road just completely breaks," said Tamblyn-Watts.

Ottawa police are advising residents and tourists to avoid the area. Evacuated businesses include the Shaw Centre, a CIBC bank, a Chapters store and the Rideau Centre mall.
'Too soon' to know cause

Ottawa Mayor Jim Watson said at an emergency meeting of city officials Wednesday afternoon that so far, there have been no injuries or missing persons recorded.

Watson said at this point it's unclear why the sinkhole formed.

"We hope to have that answer, obviously, in the next few days," Watson said.

"We just don't know how long it's going to take … it's a significant sinkhole in the downtown core," he said.

Anthony Di Monte, the city's emergency and protective services general manager, said in addition to the water main break, a gas leak also occurred, but the gas has since been shut off.

Power was also cut off to 850 customers as far east as King Edward Avenue and as far west as Elgin Street for two hours before being restored.

Di Monte said with emergency workers mitigating damage and stabilizing the area, they haven't yet had a chance to investigate the cause.

Di Monte said it wasn't clear, for example, whether the water main break might have been a contributing factor to the collapse, or whether it happened as a result of the collapse. The water main was built in 1992.

"We don't have the basic information to formulate plan yet for the next few days, " said Di Monte.
Happened near LRT work


A crowd gathered around the sinkhole, even though Ottawa police were advising residents and tourists to avoid the area. (CBC News)

The sinkhole formed near a construction site for Ottawa's light rail system, a new section of which is being dug downtown. But Watson noted that the excavation work was well below where the road collapsed.

Workers were excavating the last 50 metres of the future Rideau Station when the road fell in, said Steve Cripps, director of the city's rail implementation office.

The soil conditions in the area where the road collapsed were sandy, requiring extra precautions and different mining techniques, said Cripps.

"This is an area where they've done all the reasonable things," said Cripps.

He said it wasn't clear whether that work was connected to the collapse. The workers left the tunnel when the collapse happened and are all accounted for, said Cripps.

Work on the light rail transit system in the area will be suspended until the cause of the sinkhole can be determined and any necessary precautions have been taken.
Mayor to tour site

Watson and city officials toured the site Wednesday afternoon. The mayor said he would provide further updates as more information is learned.


The circle on the far right of the map shows the location of the Rideau Station stop for Ottawa's future light rail system. Excavation of the station finished over the weekend. The sinkhole formed Wednesday morning just next to it. (City of Ottawa)

On Sunday, Watson announced on Twitter that excavation at the future Rideau Station was complete.

A construction update from last week said crews were doing waterproofing work, installing beams and rebar, and spraying concrete at the future station. A crane was also installed at the site for future work.

Before the sinkhole formed, the road was only open to buses and taxis.