The costs of reunifying Santa Rosa’s Old Courthouse Square may actually come in below the city’s $10 million price tag for the project, if a city engineer’s recent estimate proves accurate.

The city issued a notice to potential bidders early this month that contained a construction estimate for the project of between $6.4 million and $7.2 million. That range was set by the city engineer in consultation with the city’s designer on the project, Carlile Macy, city supervising engineer Steve Dittmer said. He stressed, however, that the figure is only an estimate.

“We’ll know the true cost when the bids come in,” Dittmer said.

About a dozen contractors have expressed interest in the work to date, but that number could increase if more buy copies of the plans and submit bids, he said. The deadline to submit bids is March 30.

Construction costs are only one piece of the total project. Other costs include about $1 million that will be needed for construction management, along with $750,000 already spent for design work and $130,000 already spent for the removal of 20 trees.

But even when all those are considered, if the bids come in at the top of the city engineer’s estimate, the total project would cost just over $9 million. The cost of city staff time is not included in the estimate.

“I’m pleased we were able to work with the architect to develop a project that meets the council’s design guidelines and within the prescribed budget,” said Jason Nutt, the city’s director of transportation and public works.

If the revised number holds, it would bring the project in for substantially less than the $17 million price tag tied to a previous version of the project, which the council considered excessive. The council scrapped that version and adopted a simplified project last fall.

The true cost of the project has been a moving target and has made it difficult for the city to establish how it is going to fund the work. The City Council moved $2.4 million in general funds into the project Tuesday, nearly doubling the money set aside for the reunification.

The remainder will be funded either by borrowing money from local banks or by issuing a form of debt known as “certificates of participation,” which would use another city asset as collateral, the city’s chief financial officer, Debbi Lauchner, told the council Tuesday.

The council will select a financing option after Lauchner determines how much the city will need to borrow, which hinges on the construction contract, she said.

You can reach Staff Writer Kevin McCallum at 521-5207 or On Twitter @SRCityBeat.