The Fairfax County School Board is considering a proposal to consolidate its scattered administrative offices in a new headquarters building at the county's planned government center near Fair Oaks Mall.

The County Board of Supervisors approved a zoning plan in February under which a private developer would build the new government center on 100 acres of county land just south of the mall at Rtes. I-66 and 50. In exchange, the county would give the developer up to 146 acres of prime county-owned land. Officials hope to select a developer this summer.

The school system's offices are in 17 buildings it owns across the county, some of them 15 miles and a 40-minute drive from its headquarters in Fairfax City, where administrators' meetings are held. A new headquarters probably would consolidate about 10 of the buildings, housing 800 or more employes.

At School Board member Kohann H. Whitney's request, Superintendent Robert R. Spillane is studying whether a central building would be financially and administratively more efficient. The Board of Supervisors would have to approve the venture.

"It's a once-in-a-century opportunity and I think we ought to take a real hard look at it," Whitney said yesterday. "I think it would end up saving us money and make us operate more efficiently."

Whitney said she had heard no arguments against the idea, although it could add fuel to the argument by government center critics that roads near Fair Oaks cannot handle the increased traffic.

Whitney and County Executive J. Hamilton Lambert, who has discussed the idea with Spillane, said there would be enough land left over after the county office building is built to allow for a school building, which Lambert estimated would require up to 150,000 square feet of office space. Lambert said the school system could pay for the building by selling surplus land it owns.

Whitney said among the details to be worked out would be what to do with the system's headquarters in Fairfax City, and the administration buildings.