Traverse City commissioners will discuss options tonight (Monday) for a major repair project at the city’s wastewater treatment plant. Initial estimates last year put the project cost in the $23.5-$29 million range, but as a consulting firm nears the 30 percent mark on design work, estimates have risen to $26.1-$35.8 million. Commissioners will hear from consultants tonight on two major design options for the plant.

The wastewater treatment plant project aims to “address aging infrastructure, increase reliability, improve plant hydraulics, and resolve deficiencies in the UV disinfection system,” according to the city’s Bay Brief. Planned improvement areas – including the ages of existing equipment and current challenges – were outlined by the city as follows:

> Preliminary Screening (1994): Lacks redundancy and sufficient hydraulic capacity.
> Grit Separation (1950s, 1970s): Performs inadequately, failing to balance flow during peak influent rates.
> Primary Clarifiers (1930s, 1950s): Significant corrosion and frequent costly repairs required.
> Primary Effluent Screw Pumps (1970s): Operating beyond their expected useful life.
> UV Disinfection System (1998): Reaching end of life and under an Administrative Consent Order (ACO) from the Michigan Department of Environment, Great Lakes, and Energy (EGLE). The new system must be elevated to prevent damage during high water events.

The ACO from the state means the city is under a deadline to replace the UV system by July 2026. It’s reached the end of its useful life and will be upgraded to withstand 100-year-flood levels. The city also plans to improve preliminary treatment areas to reduce the amount of grit and particles making it downstream to the later treatment areas. City Director of Municipal Utilities Art Krueger previously said the plant’s existing grit removal equipment is obsolete and only removes about 60 percent. New technology is effective at removing up to 95 percent. That can help “reduce operating costs from removing grit further downstream,” Krueger explained.

City commissioners voted last July to hire Fleis & VandenBrink and Commercial Contracting Corporation at a cost of up to $2.2 million to complete preliminary design work on plant improvements. The contract, paid for by the city’s sewer fund, will cover 90 percent of the design work needed and provide a guaranteed maximum cost for construction. With nearly 30 percent of design work complete, the city is now at a “critical point in the design phase where some important decisions need to be made to move the project design forward to completion,” says Krueger.

After considering multiple options for every phase of work, the design team put together two major alternatives for the plant. Both include the same grit system, UV, and primary effluent screw pump replacement options. But they differ significantly in their options for preliminary screening – removing large debris from the wastewater as it comes into the plant – and for primary treatment, which separates suspended solids and scum from wastewater.

They also differ significantly in cost. Alternative 1, estimated at $26.1 million, would upgrade the existing preliminary screening and primary treatment equipment. Alternative 2, estimated at $35.8 million, recommends constructing a new headworks for preliminary screening and installing new clarifiers for primary treatment. The “reuse” versus “new construction” options explain the cost difference, with pros and cons for each option.

For example, rehabilitating instead of replacing the primary clarifiers will require reusing concrete “that is approaching the end of its expected useful life” and has higher long-term maintenance costs, according to the consulting team. “However, the lower capital costs of this project need to be considered.” Rehabilitating the primary equipment is estimated at $7.54 million, while replacing it is nearly double the cost at $14.96 million. But replacement comes with eight years longer of expected useful life and half the estimated annual maintenance expense.

Overall, Alternative 1 has an estimated useful life of 23 years for its improvements, while Alternative 2 has 29 years. Annual maintenance costs are estimated at $342,000 for Alternative 1, meanwhile, and $291,000 for Alternative 2.

In addition to selecting a design alternative, commissioners will also need to consider funding. Krueger notes that the city has applied for a low-interest loan from EGLE for 2025. But he also previously said that an influx of infrastructure funding has “woken every community up in the whole state” to project possibilities, resulting in a “lot of asks” for loans and grants. “It’s very competitive,” he said. “Costs have been going up very alarmingly.”

There’s also a shortage of skilled contractors available to do specialized work like wastewater upgrades and a “flood of work” now available for those employees, “so it’s a challenge,” Krueger previously said. For the city’s wastewater plant project, its application score with EGLE “may be in the fundable range,” but the city won’t know until late August. If the loan isn’t awarded, the city will have to bond the project – a move that will come at a higher interest rate (and thus overall cost) than via state funding. Project costs will be split between the city and the township members in the plant – including East Bay, Garfield, and Acme – along 55-45 lines, reflecting the percentage of the plant owned by those parties under a master sewer agreement.

Work is expected to be completed by summer/fall 2027. According to the Bay Brief, the last major comparable project at the wastewater treatment plant was in 2002. That project, which introduced bioreactor membrane treatment trains, cost over $31 million – a figure that would be approximately $54 million in 2024, factoring in inflation. The upcoming plant upgrades represent a significant part of approximately $48 million in water and sewer improvements planned in the city over a five-year period.

Photo Credit: Jacobs (operating firm for Traverse City's wastewater treatment plant)