Owosso advances sewer plan

Matt Kennedy with OHM Advisors gives a presentation on the sanitary storm water loan the city is considering taking out.

OWOSSO — The city took the first step Monday in applying for a $4.9-million loan to fund projects that will reduce sanitary sewer overflows and repair structural problems in pipes and manholes.

The loan is jointly administered by the Michigan Municipal Bond Authority and the Michigan Department of Environment, Great Lakes, and Energy, formerly known as the Michigan Department of Environmental Quality through its Clean Water State Revolving Fund for Wastewater Collection Systems.

The loan, if approved, would be for 20 years and carry a 2-percent interest rate. On average, a city resident would see a quarterly increase of $11.41 on their utility bill.

“The benefits of this project would be to reduce the likelihood of future sanitary sewer overflows to streets and into the Shiawassee River, increased reliability of the sewer service to residents, fewer sinkholes in roads, and an overall reduction of stormwater intrusion into the sewer system,” Matt Kennedy of OHM Advisors, the engineering firm the city contracts for various projects,” Matt Kennedy with OHM Advisors said.

A public hearing took place Monday. There were no citizen comments during the public hearing.

The council did not adopt the plan or submit an application for the loan. The public hearing was just the first step in letting the Michigan Municipal Bond Authority and The Michigan Department of Environment, Great Lakes, and Energy know that the city is interested in pursuing the loan.

“This is just a notice of intent and it puts them on notice that we plan to apply and this is what we want to do. This is not a commitment of funds this is not a commitment to the project,” City Manager Nate Henne said.

The city routinely experiences sanitary sewer overflows of untreated sewage into the Shiawassee River during flooding or heavy rain periods because some lines carry both storm water and sewage. The problem dates back many decades to when the lines first were installed.

The city has been under a consent order since 2004 to address the overflow issues.

“This wastewater problem isn’t unique to Owosso or even this area,” Mayor Chris Eveleth said. “There are communities especially surrounding Metro Detroit that are struggling with this as well.”

“The city is also tackling some of these problems on a pay as you go basis we’re using existing dollars to pay for some of these manhole and sewer line repairs. About $435,000 worth of physical work is already planned for the next fiscal year, both manhole replacement and sanitary lining. This would be in addition to that,” Henne said.

The loan and projects would be broken down into two parts to accomplish the two main goals of the project. The first portion of the project will repair sewer lines and manhole covers to prevent unnecessary stormwater from entering the system.

There are 11 manholes and approximately 18,000 feet of sewer lines that need substantial structural repairs.

The manholes and the sewer lines, for the most part, would be re-lined under the proposed project plan and some areas that are beyond repair would be replaced. The repairs will reduce sinkholes in roads, reduce sewer backups, and reduce storm and groundwater infiltration into sewers.

The second portion of the proposed project would construct a sanitary sewer overflow detention tank to hold water that overwhelms the system that currently is released into the Shiawassee River.

“Here is Owosso, you have had 21 (overflow) events in 18 years due to heavy rainfall events. The SSO detention tank is by far the most economical choice and it would be very effective in reducing the SSO associated with the overflows that have happened within the city limits,” Kennedy said.

Every time an overflow event happens, the city is required to disclose to the state and public the scope of the event, according to the city’s director of Public Services Glenn Chinavare.

The detention tank would be located on an industrial site near the corner of Chipman and Beehler Streets.

“It’s not going to run all the time, only during these surcharge events. If we know that the interceptor at Beehler street is going to surge we start pumping into that tank. When it lets up we slowly release the tank downstream to the plant,” Henne explained.

“The system is designed for a 25-year event. The size of this tank is 1 million gallons and that should be sufficient. The idea was, let’s size it larger because there are economies of scale here and if you’re going to build it making a little larger doesn’t cost too much” Kennedy said.

A second location that experiences sanitary sewer overflows is at the city’s wastewater treatment plant.

“The reason for that down at the plant is not because it’s being overwhelmed its because the collection system just upstream from the plant is being overwhelmed and currently our choice is either pump to the river or allow a lot of those upstream structures to overflow into their basements and, for us, that’s not an option,” Henne said.

“The pipes are undersized for the capacity that they’re required to move and that’s why these surges happen. The other areas are for overflow are essentially between M-52 down at Beehler Street along the river.”

He explained the tank is designed for 20 years, but much like the above ground water storage tanks, the lifespan is usually much longer than that. He estimated a 50-year lifespan.

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