The Fairfax County School Board is considering a $182 million construction plan proposed by its staff that would build eight new schools by 1991 in order to accommodate the baby boom and the system's many special programs.

But some School Board members, noting that the plan would double the annual construction budget of the area's largest school system, are questioning whether all of it is necessary.

School Board members, who heard the proposal for the first time last week, said they were surprised at the size of the 1987-1991 capital improvements proposal, especially because only a few years ago schools were being closed in the county because of declining enrollment.

"I'm concerned about the way the numbers have turned around so rapidly," said School Board Chairman Mary E. Collier of the sudden boom after years of steady or declining enrollment.

"There are going to have to be some choices made," said Laura McDowall, who chairs the board's facilities committee. "Some things are going to have to come off of that."

The board is likely to urge a county school bond referendum next fall on the spending proposals for new school construction it eventually approves.

The referendum must be approved by the county Board of Supervisors, and school needs would compete for dollars with what many say is the top spending priority of both voters and supervisors: road improvement needs in the county, where booming residential and commercial development are straining the road system.

"I don't think it's going to be easy," said School Board member Joy Korologos.

"There will be tugs on the money, and they're the main two: education and transportation," Korologos said.

In addition to the seven proposed elementary schools and one intermediate school, the plan calls for building 13 additions to elementary schools and renovating 10 elementary schools, two intermediate schools and two high schools.

Music rooms and gymnasiums would be built at 11 elementary schools, three centers for handicapped students would be constructed, and some schools renovated in earlier years would be air-conditioned.

The board plans a public hearing Jan. 13 on the proposal, officially known as the 1987-1991 Capital Improvement Program.

Added to currently funded construction, including four elementary schools opening next year, the new proposals would bring total school construction costs to $269 million through the 1991-92 school year. That would mean $48 million in annual spending, double the $20 million to $25 million of recent years.

"That seems awfully high to me," Korologos said.

School staff members said school population in the county has grown because of a higher birth rate and a strong housing market, creating the need for more schools. In addition, the board's approval of special programs, including a lower pupil-teacher ratio in some classrooms, requires that there be room for the additional classes.

School enrollment, now 125,377, will climb to more than 135,000 students by 1990-91, about what it was in 1970, according to projections. By 1995-96, it is projected that enrollment will exceed 145,000.

Much of that is attributable to a higher birth rate that has seen kindergarten enrollments start to boom locally and nationally after years of decline. Over the next five years, county elementary school enrollment is projected to grow by 21 percent, while high school enrollment is to continue to dwindle.

"It's the baby boom generation come of age," said Roger W. Webb, director of the school system's office of facilities planning services.

The new housing shooting up around the county, especially in the booming western edge, accounts for some of the proposed new construction. There is even a new 36-room elementary school proposed in the Groveton-Franconia area, until recently a neighborhood of declining enrollment, because of the massive Kingstowne development going up there.

But Webb said a major reason for the needed new construction is that special programs such as English as a Second Language classes, special education and Head Start are taking up more school space. Those programs take up 578 elementary school classrooms countywide, "the equivalent of eight 32-room schools," Webb said.

School Board efforts to lower the pupil-teacher ratio have had "significant impact," he said. By the 1989-90 school year, that will dictate 89 additional elementary classrooms, the equivalent of more than two school buildings.

Collier questioned why new schools or additions are being proposed in areas that only a few years ago saw schools closed. In McLean, where two schools were closed, 26 new classrooms are now proposed, she said. "We didn't anticipate the turnaround" in births, Webb conceded, but he said the special programs approved by the School Board account for more of the space demands than does the baby boom.

Webb said it is less expensive to build a new school than to reopen closed schools, many of them occupied by administrative offices, because of renovation costs to bring those schools to current building code standards.