Superior’s Environmental Services Division is gearing up to rehabilitate two of its combined sewer treatment plants over the next two years.

The plant in South Superior would be completed in 2020 with the one in Billings Park slated for construction in 2021.

The projects will be split with a goal of maximizing the possibility of funding the projects through the Clean Water State Revolving Fund, which offers a principle forgiveness grant with the loan. If successful in funding the South Superior project in the funding, the city could save about $560,000 on nearly the $1.9 million project. Project costs include the design work for the Billings Park plant.

The combined sewer treatment plants are auxiliary treatment facilities used when water is coming into sewer system too fast for the main treatment plant to take it in all at once.

The facilities are used about five to six times a year, said Steve Roberts, Environmental Services director.

The facilities were built in 1976 and are deteriorated, said Mike French of LHB, which designed the rehabilitation projects.

The projects will include repairing and reconstructing the asphalt liners in the basins, installing basin drains to improve dewatering of the basin, replacing effluent pumps, constructing and constructing a dewatering slab for Vactor trucks.

Roberts said adding the drain will make it a more effective system to draw down the wastewater and return it to the main plant for treatment. The system wasn’t designed to work that way originally, but it is the way it has operated over the last couple of decades, he said.

When the pumps are replaced, the capacity will be increased from about 2,300 gallons a minute to 3,200 gallons a minute, French said.

The South Superior plant has a capacity of about 6.5 million gallons and the one in Billings Park can hold about 12 million gallons.

No increase in the sewer rates is expected as a result of the project.

“The really important part is we have a relief storage structure where we can store this wastewater and then bring it back to the plant to treat it, rather than having it blow a cover off a manhole somewhere and end up in the lake,” Public Works Director Todd Janigo said.

Resolutions to seek funding for the South Superior project will likely be submitted to the Council in August for consideration because the Wisconsin Department of Natural Resources deadlines are in September, Roberts said.