A major road in Port Moody is shut down after another sinkhole on the Evergreen Line, the fourth in less than a year.
Clarke Road is closed at Seaview Drive until further notice while crews investigate the problem. Evergreen Line officials say the four-metre wide, and four-metre deep hole, which first appeared around 7 p.m. Friday, has now been filled, but the traffic detours could continue through Sunday.
It’s the fourth sinkhole to open up on the line since last October, and in each case officials have blamed problems with the tunnel-boring machine.
According to a bulletin on the Evergreen Line website, Friday’s sinkhole happened while completing maintenance under Clarke Road at Seaview Drive. It said additional ground material entered the machine’s chamber and an air pocket developed.
“The air pocket resulted in a hole in the asphalt on Clarke Road,” the bulletin said.
Port Moody Mayor Mike Clay is questioning the safety of the project and whether the soil is stable long term. He told CKNW on Saturday that there have been too many occurrences for comfort, and he doesn’t understand why the company hasn’t solved this problem.
Amanda Farrell, Evergreen’s project director, acknowledged the mayor’s concerns, and said Evergreen is working with the contractors to bring in additional experts to study the problem and figure out what to do so it doesn’t happen again.
She said that the soil conditions on this project have proved very challenging for engineers.
“Where we have had the challenges is maintaining the stability of the earth in the front of the boring machine. The contractors continue to implement more and more measures to achieve that stability,” she said, adding that the material in the soil is very abrasive.
“There is a mix of sand, and glacial till, boulders and rocks.”
Farrell said they will also be investigating the mayor’s concerns about how long it took to secure the sinkhole.
“Safety is our top priority. We have contingency plans for detours and I have heard the mayor is concerned about how long those plans were implemented, and that is something we certainly will be looking at to see whether things could have been done differently.”
In April, a sinkhole opened in the same area, again where construction crews were working on the tunnel boring machine.
At the time, Farrell said crews were not expecting another sinkhole to appear, noting work had been taking place to improve the ground in the area. When asked whether more sinkholes could be expected, Farrell said officials will be looking at future maintenance cycles and working with the contractor to make sure all precautions are taken.
Ground material getting into the tunnel-boring machine chamber during maintenance was also blamed for two sinkholes that opened up along the line last year and in January.
