Six months ago, Charlotte-Mecklenburg Schools decided to close about a dozen school buildings and combine westside elementary and middle schools into eight pre-K-8 campuses.

The goal: to help close an estimated $100 million budget shortfall.

But some of the expected savings are draining away because the cost of retrofitting the pre-K-8 schools and others touched by the closures is running roughly $1 million higher than CMS estimated.

Also, design changes, academic considerations and higher enrollment are forcing administrators to assign at least 20 mobile classrooms to the newly consolidated campuses.

None of it sits well with Joyce Waddell, one of two westside representatives on the board. She refused during Tuesday's school board meeting to support the district's 2011-12 budget request, partly over concerns about the pre-K-8 changes.

Waddell says the African-American communities affected are getting shortchanged by a plan that doesn't save as much money as promised, might not work as hoped, and crams kids onto crowded campuses.

"I'm very disappointed," she said.

"We want to make sure things are equitable and fair, and that our resources are being used wisely."

Dorothy Waddy, a longtime westside community leader, echoed those concerns.

"These people are paid big bucks to know what they're doing," she said of CMS officials. "When you bring something to the table, you're supposed to have looked at all the ins and outs of it, especially the cost.

"Somebody didn't do their homework, and they didn't really give a damn, because all of these schools were in the inner city."

The school board approved the closings in November as part of a five-month review that prompted changes at more than 60 schools. CMS said the moves would save nearly $10 million in the first two years and more than $6 million each year afterward.

CMS planner Mike Raible said in an email Friday that the campuses aren't crowded, and that the costs ran higher because principals requested additional changes.

He said the initial construction estimate for the projects was $3.3 million. During Tuesday's board meeting, he said the expense is running "somewhere in the neighborhood of $4 million and change." Asked on Friday for more exact numbers, Raible said he wasn't ready to release them.

As for changes principals requested, Raible said CMS had planned for one science classroom per school, but added a second to give schools scheduling and instructional flexibility.

He also said three of the schools - Berryhill, Ashley Park and Thomasboro - will require mobile classrooms. Raible said the higher enrollment resulted from fewer-than-expected families leaving the new pre-K-8 schools.

He said Ashley Park will get 10 mobile classrooms, as will Berryhill. Ashley Park's enrollment projections called for three mobiles, he said, but CMS is adding seven more to accommodate academic groups that have worked well for the school.

Berryhill isn't over capacity, Raible said, but will get trailers because renovating its regular classrooms proved too costly.

Thomasboro is in line for four mobiles.

"That's as of now," Waddell said in an interview. "When school starts, we might have even more."

During the school board meeting, Gorman said CMS would rather not use mobile classrooms, but they've always been part of the district's plan for dealing with the ebb and flow of student enrollments.

Raible told board members it was hard to turn the principals' requests down "when the point is to make those schools successful."

Board member Tom Tate, whose district includes the east side of Charlotte, said Raible's explanations made sense to him.

"While I would have liked (projections) to be exact," Tate said, "we're always working with the best estimates to do the work."