Cost to fix slumping riverbank keeps rising

Report to council committee details problems encountered by work crews

The riverbank keeps failing and the costs keep piling up.

Reports to be considered by a city council committee on Monday say fixing slope failures on the southeast bank of the South Saskatchewan River will cost $1.5 million more than has been approved.

A report on its way to council’s environment, utilities and corporate services committee says a project to repair a riverbank slump that created a hole in Saskatchewan Crescent cost about $1.2 million more than expected.

Excavation required to repair the slump at Saskatchewan Crescent and 16th Street revealed more unstable soil than expected. Reid Corbett, director of Saskatoon Water, said on Thursday that two and a half times more soil had to be replaced than was anticipated.

The original project’s budget was approved at $2.8 million, but the original contracts for the work totalled just above $2 million. The new total for the work is $2.96 million. “Given the nature of geotechnical projects such as this, limited information of the ground conditions is available until the excavation takes place,” the report says.

“Once the excavation started, it was determined that larger than anticipated quantities of unstable soil had to be removed.”

Corbett said a snowfall in October 2016 made work difficult as the crews began to repair the upper part of the slope so Saskatchewan Crescent could be rebuilt and reopened. Slope movement also affected the retaining wall the city built. “During the construction, there was some movement of the retaining wall, which caused us some concern,” Corbett said in an interview. “It tilted a bit on us.”

The retaining wall has since been deemed structurally sound, he said.

The extra work required $117,919 more in engineering services by Golder Associates and $799,346 more in remediation work by Celta Construction Inc. Another $300,000 will cover continuing work to combat erosion.

City council, which endorsed the repairs in 2016, must approve any contract increase higher than 25 per cent. The city administration recommends extra costs be covered by a reserve fund for riverbank stabilization.

A separate report says work to repair the riverbank in Cosmopolitan Park will cost $303,018 more than expected due to ongoing work.

Council approved a project in 2009 to spend $2.6 million to repair slumping in Cosmo Park, a stretch along the southeast riverbank below Saskatchewan Crescent between the University Bridge and Broadway Bridge.

There was some movement of the retaining wall, which caused us some concern.