New Brunswick

Engineers predict limited future erosion from Petitcodiac River bridge project

While the removal of the causeway over the Petitcodiac River in Moncton is expected to increase the width of the river threefold, engineers aren't expecting significant erosion, but they can't guarantee it.

Removal of causeway to increase river width threefold

'From what we’ve seen so far, we’ve exhibited the majority of the erosion,' said Mike Pauley, the manager of special projects development for the Department of Transportation and Infrastructure. (Shane Magee/CBC)

While the removal of the causeway over the Petitcodiac River in Moncton is expected to increase the width of the river threefold, engineers aren't expecting significant erosion, but they can't guarantee it.

This comes after Moncton city council approved a contract to reinforce 150 metres of the Riverfront Boardwalk, between the Running Room and Classic Burger at a cost of $680,000.

While the gates of the causeway are open, the complete removal of the causeway that connects Moncton to Riverview will cause the river width to swell more than it has already.

Mike Pauley, manager of special projects development for the Department of Transportation and Infrastructure, said he doesn't expect to see much more erosion.

He said the opening of part of the causeway has already caused some erosion and made them confident that future erosion will be limited.

"From what we've seen so far, we've exhibited the majority of the erosion," said Pauley.

"We did riprap in critical areas along the river bank in anticipation of that erosion. And that riprap that we did place has done its job very well."

Riprap refers to large rocks placed on the side of river banks to help fight erosion.

Changes

The gates on the Petitcodiac River causeway were opened in 2010 with an aim to rehabilitate the river.

The causeway was built in 1968 and prevented fish swimming upstream.

In the years since the gates were open, the river has seen a return of wildlife and an increased tidal bore, a wave that travels up river at high tide daily. 

Less erosion

Pauley said while you can't be sure erosion will remain minimal, engineers have done LiDAR scanning, which scans land and turns it into a 3D representation, and noticed the riverbank hasn't eroded as much as they had predicted.

The removal of the causeway will bring a new bridge, which has been built with rising sea levels in mind, and will stand two metres above the maximum predicted future tide level.

Once the causeway between Moncton and Riverview is removed in 2021, the Petitcodiac will be about three times wider under the new bridge. That's why city councillors approved a contract to reinforce 150 metres of its Riverfront Boardwalk. But an engineer with the province says they don't anticipate erosion will be a major problem. Mike Pauley is the manager of special projects development for the department of transportation and infrastructure. He spoke to Jonna Brewer. 9:06

The $61.6-million project began in 2017 and was expected to be complete in fall 2020, but it was pushed back to 2021 by the Higgs government.

"In November of 2021, we should [see] cars over the new bridge," said Pauley.

With files from Information Morning Moncton

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