Rising construction costs and quickly climbing interest rates have pushed the Farmington High School construction project about $18 million over budget, and town voters will get to decide next month how to deal with that.

School and municipal officials are asking voters next month to authorize spending another $9.7 million on the project, but are assuring that it won’t come from local taxpayers.

The state government this summer authorized an unexpectedly high level of aid for the project, so a “yes” vote on the Dec. 8 referendum would not spike a tax increase, town leaders said.

“The total cost will increase, but that won’t be on the shoulders of the community,” Town Council Chairman C.J. Thomas said Thursday.

To go beyond the $136 million school construction project that voters approved last year, the town must get a “yes” vote on the referendum, Thomas said.

That would allow it to apply the $14 million in additional state aid to cover the overruns and slightly reduce the town’s share of the overall expense.

A panel overseeing the project blamed higher interest rates, supply chain disruptions and fast-rising construction costs for the overruns.

Similar troubles have struck public and private building projects, especially during the second half of this year. Southington last month dealt with a roughly $1.5 million overrun in its $17 million library construction by downsizing the new building; instead of being 30,000 square feet, it will measure 24,000 square feet.

Farmington leaders cautioned against that approach with the high school, saying planners have already shaved more than $9 million in costs from the original plan. Those expenses won’t be restored, they said.

Planners also temporarily agreed to millions of dollars in additional reductions, such using plasterboard instead of concrete masonry walls, substituting linoleum for tile floors, and skipping construction of new tennis courts and a new ballfield. Those expenses could be restored now because of the new state aid.

Even after all of those cutbacks, actual price quotes last month turned out to be 5 percent higher than what was projected in 2021. The town received more than 120 bids for materials, electrical work, carpentry, plumbing and other components.

The full budget for all construction labor and materials had been set at $115.6 million, but the lowest bids in October totaled $121.5 million, according to Lorel Purcell of O&G Industries, the town’s construction manager.

“With some of the bid packages, we only received single bids —they over our estimates,” she told the town council last week. “The intent is to go out and rebid, and hopefully it will go down a little bit.”

Council members said it will be essential for voters to understand that the unexpected state aid will mean there isn’t a cost for Farmington’s budget.

“That’s a really hard thing to communicate as we go forward,” council member Rafeena Bacchus Lee said. “The net municipal cost to the town will actually decrease because we have access to the $14 million.”

Project planners said the $14 million will be used to cover the new overruns and restore the tennis courts, ballfield and other reductions that the panel had temporarily agreed to.

Westview Terrace resident Tim Kelly said the building committee’s work so far hasn’t been good enough.

“The basic job of any building committee is to deliver the finished project on time and under budget — $10 million over budget is a huge miss,” Kelly told the council. “I think we can expect in 18 to 20 months, when the new building is 70 percent complete, to receive another $10 million emergency funding request. "

Kelly suggested the town could hold a referendum requesting $20 million so it could cover future contingencies, or else go back to the previously rejected idea of renovating the current high school instead of building a new one.

The council, however, agreed that the project is basically on track and agreed to schedule a referendum for Dec. 8. Thomas said the town will distribute information to voters well before then.