Fairfax County supervisors attacked plans yesterday for a $27.8 million government center near Fort Belvoir, questioning whether the proposed building is bigger and more expensive than necessary.

The five-story facility, dubbed the South County Center, would be built by Madison Development Partners, which would lease the building to the county for $2.9 million a year for up to 30 years, when the county could buy it for $1. The building would pull together employees now housed in seven office buildings where the county leases space for $1.5 million a year.

Fairfax County Executive Robert J. O'Neill Jr., who brought the proposal to the board, defended the project as a cost-effective way to consolidate employees and spur economic development in the downtrodden Route 1 corridor.

But five of the board's 10 members raised serious objections to the proposal's cost and scope, and several, including Chairman Kathleen K. Hanley (D), said they weren't sure they would support it. A public hearing on the project is scheduled for Jan. 24.

The most vocal critic, Supervisor Stuart Mendelsohn (R-Dranesville), warned that the project will be compared to the county's main government center, a grandiose marble-and-mahogany building derided as the "Taj Mahal" when it was built in 1992.

"This began as a small project," Mendelsohn said of the South County Center. "Now this is turning into a junior government center. . . . We're going to have the same resentment all over again."

Marcia P. Dykes, president of Citizens for Sensible Taxation, said it was "totally unreasonable" for the county to consider such a project in light of chronic overcrowding in Fairfax schools.

"We're building a mini-Taj," Dykes said. "Here we are with all these glorious new office buildings, and now we want to build more. . . . It's totally unacceptable to have kids sitting in school trailers while the county wants to put up another $27 million building."

Under the proposal, Madison Development would build the center on a vacant 8.75-acre parcel of land on Route 1 just north of Buckman Road. In return, Madison would be allowed to build private offices on a former school site nearby--providing what county officials characterize as a vital investment in the area.

"We're looking at this issue as part of a broader revitalization effort," said O'Neill, who also said the proposed building would alleviate crowding in the current offices while also providing room to grow.

But Mendelsohn and other board members questioned whether the county needs that large a building, which would provide 135,000 square feet of space for employees now housed in 86,000 square feet of rented offices.

"It's twice as much as we're paying now," said Supervisor Elaine N. McConnell (R-Springfield). "We need some justification on why we're telling the public we're doing this."

In other business yesterday, supervisors bid farewell to two-term board member Robert B. Dix Jr. (R-Hunter Mill), who was defeated in November by Democrat Catherine M. Hudgins. Dix told board members that he was proud of the transportation and recreation projects completed and started during his tenure, which saw the Dulles area become a hotbed of high-tech companies and development.

"We have agreed on far more than we have disagreed," said Dix, an often confrontational supervisor who sounded a note of conciliation in his farewell.

The board also said goodbye to recreation director Wes "Mickey" Kendrick, 53, who retired last week after inking a deal to work as a part-time county consultant for $1,000 a week through next September.

The arrangement, which allows Kendrick to collect retirement benefits while working for the county, was criticized by Dykes and others as an unwarranted windfall for Kendrick. But county administrators say they need Kendrick to help oversee $1.4 million in improvements to athletic fields during the months after his retirement.

CAPTION: Fairfax County Executive Robert J. O'Neill Jr. said the proposed government center would be economical and would spur development along Route 1.