Birdwatchers blame REM project for sinkholes in Saint-Laurent borough wetland

Another sinkhole has opened up in a stretch of green space in Montreal's Saint-Laurent borough and local activists say construction of the city's new light-rail network is to blame.

For years, birdwatchers and nature lovers have flocked to the stretch of green space between highways 40 and 20 known as Technoparc.

"I come here after work. I come here on weekends," Graham Eady said.

"It's just a great place to take a break from everything, you know?"

But the park is changing and not for the better, he said. Dried trees and dirt are what's left of the Herron Pond wetlands and sinkholes are popping up throughout the park, he said.

He's worried his beloved bird-watching spot is in danger.

"Where would I go? Who wants to take an hour's drive to Terrebonne or another hour's drive west to Saint-Martin? For me it's like 15 minutes from home," said Eady.

Protest planned as group blames REM

Groups like Technoparc Oiseaux say drilling for the Réseau express métropolitain (REM) has destabilized the soil, causing sinkholes that have been draining the wetland.

The group says the REM construction is the only major excavation work in the area.

Technoparc Oiseaux is holding a protest at the park on Sunday, saying in a statement that the natural environment of the Technoparc is "constantly in danger."

"Canadians are asking their elected officials to take concrete actions to ensure the protection of the natural environments of the Technoparc de Montréal and the adjacent federal lands," the statement says.

Katherine Collin, a spokesperson for the group, told CBC Montreal's Daybreak on Wednesday the most recent sinkhole opened up in a wooded area next to a marsh, though it qualifies as a wetland.

Crews have been filling the sinkhole, but the wooded buffer is crucial for nesting birds, she said, and "the importance of these buffers to the marsh really can't be overstated."

She said she would like to see an independent team to be brought in to review the situation and come up with remediation strategies. From restocking fish, to restoring vegetation, there's a lot of work to do, she said. From there, she said her group wants the land protected.

REM says no correlation, but fixing issue

The group behind the REM project,  Caisse de dépôt et placement du Québec Infra (CDPQ Infra), says in a statement that it has analyzed the issues in the park.

The placement of the tunnel boring machine paired with soil composition could create cavities,but an investigation revealed there is no correlation between the sinkhole in the marsh and the draining of the pond, the group says.

Regardless, CDPQ Infra says it is filling in the sinkhole.

REM spokespersons Jean-Vincent Lacroix said there is a team inspecting the surface to ensure any damage is corrected. 

He said construction did cause some soil settlement that will be repaired, but it's not just the REM project damaging the natural area. Extreme weather over the last decade has played a role as well, he said.

The boring machine has reached rock, he said, and there shouldn't be any more soil settling as crews tunnel to the airport.

"We knew there would be some challenges and we are dedicated to repair any ground settlement that occurs," said Lacroix, describing the CDPQ Infra as dedicated to preserving the environment as much as possible.