FAYETTEVILLE — Aldermen are at odds with city staff and hired engineers about how to proceed with plans for a downtown parking deck.

Construction on the three-story, 246-space deck is scheduled to begin this spring and take 12 to 18 months to complete.

Initial drawings showed a 3,500-square-foot liner building spanning the southeast corner of the parking deck at Spring Street and School Avenue, on the south end of the Walton Arts Center property. The building was to be used by the city’s Parking Management Division and possibly the Police Department.

Plans were recently scaled back, however, because of cost constraints. Designs presented Tuesday at a City Council agenda-review session only included a 1,500-square-foot liner building along Spring Street on the south end of the parking deck. A rain garden was shown along School Avenue with a patio — and no building underneath — at the southeast corner of the deck.

The lack of an east liner building surprised several members of the council.

“This is the first time I realized there’s no liner building,” Mark Kinion, Ward 2 alderman, said Tuesday.

“I don’t want to have another dead space in our downtown,” said Sarah Marsh, Ward 1 alderwoman. “When you’re designing a walkable city, every block matters. And having activity and storefront windows at every block is important.”

Paul Becker, city finance director, reminded aldermen, as he has in the past, that proceeds from a $6.2 million bond issue cannot be used to build commercial spaces. The liner buildings, if used to house private businesses, would have to be paid for with another source.

David Jurgens, Fayetteville’s utilities director who has been overseeing the project, said major revisions to deck design have potential to delay the project, which has been talked about for more than two years.

City officials have said the parking deck must be built by December 2015 — three years after bonds were issued — or bondholders’ tax-exempt status could be threatened.

Removing the portion of the liner building along School Avenue will reduce project costs by about $250,000, Mayor Lioneld Jordan said.

Jurgens said a larger liner building also has potential to reduce the number of parking spaces that can be built. “The primary objective is to put parking spaces in the area,” he said.

Marsh suggested putting a foundation in place where an east liner building could be built during a second phase of the project.

“It’s really important we get this right,” she said.

Marsh and Alan Long, Ward 4 alderman, mentioned the possibility of using reserve money to pay for added costs.

Jordan had previously committed to only using bond money to pay for the parking deck. The bonds will be repaid using fees and fi nes from the city’s paid parking program — not general taxpayer money.

The mayor said Tuesday, however, he’d give staff and engineers with Garver LLC a month to identify other options for the liner building. He asked designers to identify how much a larger liner building — or a foundation — would cost; how many spaces would be lost; and the potential impact on project timeline.

According to a timeline presented Tuesday, city officials plan to award a construction contract in April. An initial construction timeline had work beginning in March or April 2013 and ending by the end of this year.