Newfound problems nearly double city storm damage

Superior’s City Council might have gotten away with bonding for $2 million to repair the city’s storm damage.

That was before the city’s Environmental Services Division discovered a problem that developed resulting from the June 19-20 flooding that could potentially double those initial estimates for repairs.

Gravel and sediment from city roads filled nearly one-sixth of one of the city’s three combined sewer treatment plants, according to Engineering Manager Steve Roberts with the Environmental Services Division.

That newly discovered problem prompted Finance Director Jean Vito to double initial estimates for repairing city infrastructure from $2 million to $4 million because the treatment plant will require dredging, she told city councilors Tuesday night.

The council approved the measure to seek $5 million in promissory notes and/or a state trust fund loan to pay for the infrastructure repairs.

Vito said the original plan was to seek $2 million to repair the damage before the problem at the Wastewater Treatment Plant’s combined sewer overflow plant was discovered.

“During the storm event, we were receiving a lot of gravel and what would be associated with washed out roads and streets that were coming into our CSTP building,” said Dan Romans, Environmental Services administrator. “We normally have screens that take out rags or wood or whatever can get washed into the system.”

However, unlike the large items the screens normally block, the gravel and road debris was able to get through, Romans said.

Roberts was working on the calculations Wednesday to determine the cost of removing that debris, which will require dredging. By Thursday, he estimated the costs for dredging to be around $1.5 million.

He said normal settling in the treatment facility will affect the capacity of the pond after 30-50 years, but the gravel that traveled into the system during the storm accelerated that timeline.

“The amount of sediment that washed in actually created an island … in a place that was actually supposed to be 14 feet deep,” Roberts said. He said he was still trying to determine how much sediment reached the pond over time and how much was a direct result of flooding.

“The majority of the basin is in pretty good shape but the area right where flow comes into the pond is where there is the biggest accumulation of debris,” Roberts said.

The problem only affected the overflow treatment facility near the Wastewater Treatment Plant. Combined sewer treatment plants that serve Billings Park and South Superior were not affected in the same way because the facilities don’t have a permanent basin of water, Roberts said. While sediment has been an issue at those facilities in the past, it’s a matter of using a loader to remove debris.

The overflow treatment plant affected is the only one that has a permanent water-filled basin, which makes dredging necessary, Roberts said.

Before approving the borrowing, Councilor Dan Olson asked if the city would be able to use state or federal aid — if the city receives any — to repay the debt.

Vito said she would recommend it.

The council also approved about $9.6 million in bonds to refund old debt to reduce interest rates and pay for improvements at the Moccasin Mike Landfill.

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