City council members voted unanimously to move ahead with a new $17. 6 million wastewater treatment plant, a project that will be paid for in part with an increase in sewer rates for residents over the next few years.

The project, described as one of the largest in the city’s history, is necessary because the current facility on Muzzy Road is aging and nearing its capacity. Once built, the new facility will be able to treat about 3.5 million gallons of wastewater a day. It will be built near the current facility, which will remain in place and treat about 1 million gallons per day, for a total of 4.5 million gallons.

The cost of the project will be paid, in part, with an increase in sewer rates. Average monthly bills could rise by about $6 a year for the next three years. Council members approved a ordinance to raise the sewer rates Tuesday.

While council members said they didn’t want to raise the rates, they said the project is necessary if the city wants to grow or attract new business in the future.

“I’m not a fan of it, but we have to do it,” said Doug Hoffman, an at-large council member.

The city is also seeking a loan from the Ohio Environmental Protection Agency’s Division of Environmental and Financial Assistance to help pay for the project.

Initially, the project was expected to cost close to $20 million, but that initial bid was well above the city’s initial estimates. The city sought a second round of bids, eventually accepting a proposal for $17.6 million from the Dugan & Meyers Construction Co.

The city was able to save more than $2 million in the second bid in part because it sought equipment from more manufacturers during the rebidding process, said Chad Hall, superintendent for the wastewater treatment plant.

He said seeking more manufacturers for equipment helped make the process more competitive and cut the price.

“The manufacturers got a little sharper pencils,” Hall said.

Council members also voted to approve Amy White as a new council member for an open at-large seat. White, a financial aid analyst at Urbana University, will replace Larry Lokai, who retired earlier this year. White is expected to attend the next city council meeting.