BRUNSWICK, Maine — Construction of the new police station has been delayed for a month because the project’s contractors say a more expensive foundation will be required to support the building, increasing its cost by $175,000.

And the unexpected expense might affect the project budget meant to cover mistakes and accidents that happen during actual construction.

Work on the police station was supposed to start later this month or in early November, but now will begin in December, said Jeff Shaw of Donham and Sweeney Architects, the project’s architecture firm.

The delay is the result of a soil study conducted by Ledgewood Construction that found loose sediment where the foundation will go, according to a Sept. 20 email sent by Shaw to Town Manager Gary Brown.

Ledgewood is recommending an 18-inch-thick foundation, which is more expensive than the 4-inch one in the original plan, according to a memo sent by Brown to the Town Council.

The town has accepted Ledgewood’s recommendation, according to Brown’s memo.

The extra expense has not changed the $5.6 million budget, Brown said Tuesday, but the additional costs could take a bite out of the project’s contingency budget.

“It increases the risk of us not having sufficient funds at the end,” Shaw said.

As part of every construction project, the architect said there is always a contingency budget that is set aside from the costs of actual construction. This portion of the total budget is meant to cover any mistakes or accidents that occur.

“It’s here to cover all the pieces that will go wrong,” the architect said, emphasizing that bumps in the road are inevitable for any construction project.

Shaw said his firm’s recommended size for the contingency in any construction project is usually 8 to 10 percent of the total construction costs.

According to the email Shaw sent to Brown, the new expense might cause the contingency budget to dip well below that.

“The owner’s contingency was included in the project budget and set at 6 percent of the construction cost,” Shaw said in the email. “It would be cut by more than half if it had to absorb the entire increase. It is risky to proceed with such a low contingency, typically we do not recommended carrying less than 5 percent owners contingency at the start of a project.”

But until the architecture firm receives its final bids from subcontractors sometime in mid-November, nothing is certain.

“The big message is we don’t know what the bids will be,” Shaw said.

When the bids have been received, Shaw said his firm will vet them to make sure they cover every aspect of the construction process and let the town decide how to proceed.

“All we know is the foundation is going to cost more than expected,” Brown said.

Despite the risk of losing funds from the contingency budget, the town manager said there could be a more favorable outcome, too.

Since the $5.6 million budget is based on an incomplete plan and preliminary bids made earlier this year, Brown said it’s possible the construction costs could end up less than projected, leaving more room for the costly foundation in the budget.

Two Brunswick Town Council members wondered why the additional cost wasn’t discussed at Monday night’s meeting. All councilors received the memo from Brown about the change on Sept. 20.

“I just assumed we were going to hear about it last night,” Councilor Benet Pols said Tuesday.

Councilor Sarah Brayman echoed Pols’ concerns.

“If this is just a normal mistake, why wouldn’t you just mention it?” Brayman said.

Brown said “there was no deliberate attempt to not discuss it.” But he said he didn’t want to report on the update until he had full information on where the new costs will come out of the budget, which will be determined when the final bids are made and presented next month.

Councilor Ben Tucker said he is not concerned about the development because it’s a part of the construction process.

“I’m not alarmed by it because engineers have to do their job and get the right foundation,” Tucker said. “I’m not going to second-guess the engineers here.”

Shaw said that despite the possibility of the project’s increased risk, he wanted to remind everyone that risk is a part of every construction project.

“[This project] is still eminently doable, but it relies on a lot of things that are beyond the control of the construction team,” the architect said.