Nearly $20 million was shaved from cost estimates for a new Mitchell Park Library and Community Center building following an intensive, urgent reexamination of architect's earlier estimates this week, according to Library Director Diane Jennings.

The matter is to come before the City Council Monday night.

The price of the most popular proposal -- constructing a new community center/library -- is now $42.8 million, down from a high estimate of $62 million Jennings said. Building just a new library (without including the community center) is now expected to cost $22.5 million, not the $38.5 million previously estimated.

The differences stem from scaling back from 2009 dollars to 2006 dollars (10 percent annual inflation was assumed), tightening up the amount added for unknown costs, and reducing the estimated cost of relocating a traffic light and utilities, Jennings said.

She emphasized the estimates are still preliminary and not based on an actual design, a point reiterated by Library Advisory Commission member John Stucky.

"They're only estimates and they have nothing to do with reality right now because we haven't even determined yet what's going to happen at Mitchell Park," he said.

The reevaluation was prompted by staff following a comparison to San Jose's recently opened Cambrian Library, which at 28,000 square feet cost $13.4 million.

"It makes sense people are going to look at that," Jennings said.

Several differences account for the discrepancy, Jennings said.

The Mitchell Park site is twice the size of Cambrian's, she said. Construction costs were lower when the Cambrian project was bid 18 months ago, a very competitive time -- San Jose received nine bids with good prices, Jennings said.

Jennings said the consultants initially provided no breakdown of costs and city staff members wanted to know more. The consultants were aiming for conservative -- meaning high -- estimates, but more realistic costs were deemed more useful, Jennings said.

The inflation to 2009 dollars was unnecessary, Jennings said.

"In truth, we really don't know when that project might be built," she said.

Alison Cormack, who gathered 650 signatures in support of an expanded Mitchell Park Library with a friend, said she doesn't think there's a "magic" price.

"I think there's a growing awareness that what exists now is insufficient," she said. "I'm definitely interested in what the project will end up costing and the way the city chooses to fund it."

The proposed expansion/reconstruction is expected to go on the June 2008 ballot. A measure to finance a new police headquarters building could also be on the same ballot.

A previous effort to improve Mitchell Park was struck down in 2002, coming just shy of the 66 percent of votes needed for approval. That measure would have included the Children's Library reconstruction, which is underway now.

The City Council will hear presentations and comments about the Mitchell Park proposal and other library improvements at 7 p.m., Monday, Dec. 4 but is not scheduled to vote on the issue until Dec. 11.